 
INTRODUCTIONUSE OF THE MICROSCOPEThere is probably no laboratory instrument whose usefulness depends so much upon proper manipulation as the microscope, and none is so frequently misused by beginners. Some suggestions as to its proper use are, therefore, given at this place. It is presumed that the reader is already familiar with its general construction (Fig. 1).
Illumination.—Good work cannot be done without proper illumination. It is difficult to lay too much stress upon this point. The best light is that from a white cloud. Illumination may be either central or oblique. Central illumination is to be used for all routine work. To obtain this, the mirror should be so adjusted that the light from the source selected is reflected directly up the tube of the microscope. This is easily done by removing the eye-piece and looking down the tube while adjusting the mirror. The eye-piece is then replaced, and the light reduced as much as desired by means of the diaphragm. Oblique illumination is to be used only to bring out certain structures more clearly after viewing them by central light: as, for example, to show the edges of a hyaline cast by throwing one of its sides into shadow. Oblique illumination is obtained in the more simple instruments by swinging the mirror to one side, so that the light enters the microscope obliquely. The more The amount of light is even more important than its direction. It is regulated by the diaphragm. It is always best to use the least light that will show the object well. Unstained objects require very subdued light. Beginners constantly use it too strong. Strong light will often render semitransparent structures, as hyaline casts, entirely invisible (Figs. 2 and 3). Stained objects, especially bacteria, require much greater light.
If the reflection of the window-frame or other nearby object is seen in the field, the condenser should be lowered a little. Focusing.—It is always best to "focus up," which saves annoyance and probable damage to slides and objectives. This is accomplished by bringing the objective There will be less fatigue to the eyes if both are kept open while using the microscope, and if no effort is made to see objects which are out of distinct focus. Fine focusing should be done with the fine adjustment, not with the eye. An experienced microscopist keeps his fingers almost constantly upon one or other of the focusing adjustments. Greater skill in recognizing objects will be acquired if the same eye be always used. To be seen most clearly, an object should be brought to the center of the field. Magnification.—The degree of magnification should always be expressed in diameters, not times, which is a misleading term. The former refers to increase of diameter; the latter, to increase of area. The comparatively low magnification of 100 diameters is the same as the apparently enormous magnification of 10,000 times. Magnification may be increased—(a) by using a higher power objective, which is the best way; (b) by using a higher eye-piece; or (c) by increasing the length of tube. Eye-pieces and Objectives.—The usual equipment consists of one- and two-inch eye-pieces, and two-thirds, one-sixth, and one-twelfth inch objectives. These are very satisfactory for clinical work. It is an advantage to add a one-half-inch eye-piece for occasional use with the two-thirds objective. The one-sixth should have an especially long working distance, otherwise it cannot be used satisfactorily with the Thoma-Zeiss blood-counting Objectives are "corrected" for use under certain fixed conditions, and they will give the best results only when used under the conditions for which corrected. The most important corrections are: (a) For tube length; (b) for thickness of cover-glass; and (c) for the medium between objective and cover-glass. (a) The tube length with which an objective is to be used is usually engraved upon it—in most cases it is 160 mm. (b) The average No. 2 cover-glass is about the thickness for which most objectives are corrected. Low powers do not require any cover-glass. A cover should always be used with high powers, but its exact thickness is more important in theory than in practice. (c) The correction for the medium between objective and cover-glass is very important. This medium may be either air or some fluid, and the objective is hence either a "dry" or an "immersion" objective. The immersion fluid generally used is cedar oil, which gives great optical advantages because its index of refraction is the same as that of crown glass. It is obvious that only objectives with very short working distance, as the one-twelfth, can be used with an immersion fluid. To use an oil-immersion objective a drop of the cedar oil which is prepared for the purpose should be placed upon the cover, and the objective lowered into it and then brought to a focus in the usual way. Immediately after use the oil should invariably be wiped off with lens paper, or a soft linen handkerchief moistened with saliva. Care of the Microscope.—The microscope is a It is most convenient to carry a microscope with the fingers grasping the pillar and the arm which holds the tube; but since this throws a strain upon the fine adjustment, it is safer to carry it by the base. To bend the instrument at the joint, the force should be applied to the pillar and never to the tube or the stage. Lens surfaces which have been exposed to dust only should be cleaned with a camel's-hair brush. Those which are exposed to finger-marks should be cleaned with lens paper, or a soft linen handkerchief wet with saliva. Particles of dirt which are seen in the field are upon the slide, the eye-piece, or the condenser. Their location can be determined by moving the slide, rotating the eye-piece, and lowering the condenser. Oil and balsam which have dried upon the lenses and resist saliva may be removed with alcohol or xylol; but these solvents must be used sparingly and carefully, as there is danger of softening the cement. Care must be taken not to get any alcohol upon the brass parts, as it will remove the lacquer. Balsam and dried oil are best removed from the brass parts with xylol. Measurement of Microscopic Objects.—Of the several methods, the most convenient is the use of a The principal microscopic objects which are measured clinically are animal parasites and their ova and abnormal blood-corpuscles. The metric system is used almost exclusively. For very small objects 0.001 mm. has been adopted as the unit of measurement, under the name micron. It is represented by the Greek letter µ. For larger objects, where exact measurement is not essential, the diameter of a red blood-corpuscle (7 to 8 µ) is sometimes taken as a unit. CHAPTER ITHE SPUTUMPreliminary Considerations.—The morning sputum or the whole amount for twenty-four hours should be collected for examination. In beginning tuberculosis tubercle bacilli can often be found in that first coughed up in the morning when they cannot be detected at any other time of day. Sometimes, in these early cases, there are only a few mucopurulent flakes which contain the bacilli, or only a small purulent mass every few days, and these may easily be overlooked. As a receptacle for the sputum a clean wide-mouthed bottle with tightly fitting cork may be used. The patient must be particularly cautioned against smearing any of it upon the outside of the bottle. This is probably the chief source of danger to those who examine sputum. When the examination is begun, the sputum should be spread out in a thin layer in a Petri dish, or, better, between two small plates of glass, like photographic plates. It may then be examined with the naked eye—best over a black background—or with a low power of the microscope. The portions most suitable for further examination may thus be easily selected. After an examination the sputum must be destroyed by heat or chemicals, and everything which has come in contact with it must be sterilized. The utmost care must be taken not to allow any of it to dry and become disseminated through the air. Examination of the sputum is most conveniently I. PHYSICAL EXAMINATION 1. Quantity.—The quantity expectorated in twenty-four hours varies greatly: it may be so slight as to be overlooked entirely in beginning tuberculosis; and it may be as much as 1000 c.c. in bronchiectasis. 2. Color.—Since the sputum ordinarily consists of varying proportions of mucus and pus, it may vary from a colorless, translucent mucus to an opaque, whitish or yellow, purulent mass. A yellowish-green is frequently seen in advanced phthisis. A red color usually indicates the presence of blood. Bright red blood, most commonly in streaks, is strongly suggestive of phthisis. It may be noted very early in the disease. A rusty red sputum is the rule in croupous pneumonia, and was at one time considered pathognomonic of the disease. "Prune-juice" sputum is said to be characteristic of "drunkard's pneumonia." A brown color, due to altered blood-pigment, follows hemorrhages from the lungs. Gray or black sputum is observed among those who work much in coal-dust, and is occasionally seen in smokers who "inhale." 3. Consistence.—According to their consistence, sputa are usually classified as serous, mucoid, purulent, seropurulent, mucopurulent, etc., which names explain themselves. As a rule, the more mucus and the less pus and serum a sputum contains, the more tenacious it is. II. MICROSCOPIC EXAMINATION The portions most likely to contain structures of interest should be very carefully selected, as already described. The few minutes spent in this preliminary examination will sometimes save hours of work later. Opaque, white or yellow particles are frequently bits of food, but may be cheesy masses from the tonsils; small cheesy nodules, derived from tuberculous cavities and containing many tubercle bacilli and elastic fibers; Curschmann's spirals, or small fibrinous casts, coiled into little balls; or shreds of mucus with great numbers of entangled pus-corpuscles. The sputum should always be examined, both unstained and stained. A. UNSTAINED SPUTUM The particle selected for examination should be transferred to a clean slide, covered with a clean cover-glass, and examined with the two-thirds objective, followed by the one-sixth. It is convenient to handle the bits of sputum with a wooden toothpick, which may be burned when done with. The platinum wire used in bacteriologic work is less satisfactory because not usually stiff enough. The more important structures to be seen in unstained sputum are: elastic fibers, Curschmann's spirals,
1. Elastic Fibers.—These are the elastic fibers of the pulmonary substance (Fig. 4). When found in the sputum, they always indicate destructive disease of the lungs, provided they do not come from the food, which is a not infrequent source. They are found most commonly in phthisis: rarely in other diseases. Advanced cases of tuberculosis often show great numbers, and, rarely, they may be found in early tuberculosis when the bacilli cannot be detected. In gangrene of the lung, where they would be expected, they are frequently not found, owing, probably, to the presence of a ferment which destroys them. To find elastic fibers when not abundant boil the sputum with a 10 per cent. solution of caustic soda until it becomes fluid, add several times its bulk of water, and centrifugalize, or allow to stand for twenty-four hours in a conical glass. Examine the sediment microscopically.
2. Curschmann's Spirals.—These peculiar structures are found most frequently in bronchial asthma, of which they are fairly characteristic. They may occasionally be met with in chronic bronchitis and other conditions. Their nature has not been definitely determined. Macroscopically, they are whitish or yellow, twisted threads, frequently coiled into little balls (Fig. 5, I.). Their length is rarely over half an inch, though it sometimes exceeds two inches. Under a two-thirds objective they appear as mucous threads having a clear central fiber, about which are wound many fine fibrils (Fig. 5, II. and III.). Leukocytes are usually present within them, and sometimes Charcot-Leyden crystals. The central fiber is not always present.
They are colorless, pointed, often needle-like, octahedral crystals (Fig. 6). Their size varies greatly, the average length being about three or four times the diameter of a red blood-corpuscle. Other crystals—hematoidin, cholesterin, and, most frequently, fat needles—are common in sputum which has remained in the body for a considerable time.
4. Fibrinous Casts.—These are fibrinous molds of the smaller bronchi. Their size varies with that of the bronchi in which they are formed. They may, rarely, Fibrinous casts are characteristic of fibrinous bronchitis, but may also be found in diphtheria of the smaller bronchi. Very small casts are often seen in croupous pneumonia.
5. Actinomyces Bovis (Ray-fungus).—In the sputum of pulmonary actinomycosis and in the pus from actinomycotic lesions elsewhere small, yellowish, "sulphur" granules can be detected with the unaided eye. The fungus can be seen by crushing one of these granules between slide and cover, and examining with a low power. It consists of a network of threads having a more or less radial arrangement, those at the periphery presenting club-shaped extremities (Fig. 8). This organism, also called Streptothrix actinomyces, apparently stands midway between the bacteria and the molds. It stains by Gram's method. 6. Molds.—The hyphÆ and spores of various molds are occasionally met with in the sputum. They are usually the result of contamination, and have little significance. The hyphÆ are rods, usually jointed or branched (Fig. 58), and often arranged in a meshwork (mycelium); the spores are highly refractive spheres. Both stain well with the ordinary stains. B. STAINED SPUTUM Structures which are best seen in stained sputum are bacteria and cells. 1. Bacteria.—Only those of some clinical importance will be considered. They are: tubercle bacilli; staphylococci and streptococci; pneumococci; bacilli of FriedlÄnder; and influenza bacilli. (1) Tubercle Bacillus.—The presence of the tubercle bacillus may be taken as positive evidence of the existence of tuberculosis somewhere along the respiratory tract, most likely in the lung. In laryngeal tuberculosis they are not easily found in the sputum, but can nearly always be detected in swabs made directly from the larynx. Recognition of the tubercle bacillus depends upon the fact that it stains with difficulty; but that when once stained, it retains the stain tenaciously, even when treated with a mineral acid, which quickly removes the stain from other bacteria. The most convenient method for general purposes is here given in detail:
In films stained by Gabbet's method tubercle bacilli, if present, will be seen as slender red rods upon a blue background of mucus and cells (Plate II, Fig. 2). They average 3 to 4 µ in length—about one-half the diameter of a red blood-corpuscle. Beginners must be warned against mistaking the edges of cells, or particles which have retained the red stain, for bacilli. The appearance of the bacilli is almost always typical, and if there seems room for doubt, the structure in question is probably not a tubercle bacillus. They may lie singly or in groups. They are very frequently bent and often have a beaded appearance. It is possible that the larger, beaded bacilli indicate a less active tuberculous process than do the smaller, uniformly stained ones. Sometimes they are present in great numbers—thousands in a field of the one-twelfth objective. Sometimes several cover-glasses must be examined to find a single bacillus. At times they are so few that none are found in stained smears, and special methods are required to detect them. The number may bear some relation to the severity of the disease, but this relation is by no means constant. The mucoid sputum from an incipient case sometimes contains great numbers, while sputum from large tuberculous cavities at times contains very few. Failure to find them is not conclusive, though their absence is much more significant when the sputum is purulent than when it is mucoid.
When they are not found in suspicious cases, one of the following methods should be tried:
There are a number of bacilli, called acid-fast bacilli, which stain in the same way as the tubercle bacillus. Of these, the smegma bacillus is the only one likely ever to cause confusion. It, or a similar bacillus, is sometimes found in the sputum of gangrene of the lung. It occurs normally about the glans penis and the clitoris, and is often present in the urine. The method of distinguishing it from the tubercle bacillus is given later (p. 127). Other bacteria than the acid-fast group are stained blue by Gabbet's method. Those most commonly found are staphylococci, streptococci, and pneumococci. Their presence in company with the tubercle bacillus constitutes mixed infection, which is much more serious than single infection by the tubercle bacillus. It is to be remembered, however, that a few of these bacteria may reach the sputum from the upper air-passages. Clinically, mixed infection is evidenced by fever. (2) Staphylococcus and Streptococcus (p. 262).—One or both of these organisms is commonly present in company with the tubercle bacillus in the sputum of advanced phthisis (Plate II, Fig. 2). They are often found in bronchitis, catarrhal pneumonia, and many other conditions. (3) Pneumococcus (Diplococcus of FrÄnkel).—The pneumococcus is the causative agent in nearly all cases
Recognition of the pneumococcus depends upon its morphology, the fact that it is Gram-staining, and the presence of a capsule. Numerous methods for staining capsules have been devised, but few are satisfactory. Buerger's method is excellent. It is especially useful with cultures upon serum media, but is applicable also to the sputum. Smith's method usually gives good results, as does also the more simple method of Hiss (p. 263). The sputum should be fresh—not more than three or four hours' old.
(4) Bacillus of FriedlÄnder (Bacillus mucosus capsulatus).—In a small percentage of cases of pneumonia, this organism is found alone or in company with the pneumococcus. Its pathologic significance is uncertain. It is often present in the respiratory tract under normal conditions. FriedlÄnder's bacilli are non-motile, (5) Bacillus of Influenza.—This is the etiologic factor in true influenza. It is present, often in large numbers, in the nasal and bronchial secretions, and is also found in the local lesions following influenza. Chronic infection by influenza bacilli may be mistaken clinically for tuberculosis, and they should be searched for in all cases of obstinate chronic bronchitis. Their recognition depends upon the facts that they are extremely small bacilli; that most of them lie within the pus-cells; that their ends stain more deeply than their centers, sometimes giving the appearance of minute diplococci; and that they are decolorized by Gram's method of staining (Fig. 11). They are stained blue in Gabbet's method for tubercle bacilli, but are more certainly recognized by Smith's method or by Gram's method, followed by Bismarck brown or fuchsin, as follows:
2. Cells.—These include pus-corpuscles, epithelial cells, and red blood-corpuscles. (1) Pus-corpuscles are present in every sputum, and at times the sputum may consist of little else. They are the polymorphonuclear leukocytes of the blood, and appear as rounded cells with several nuclei or one very irregular nucleus (Fig. 8 and Plate II, Fig. 2). They are frequently filled with granules of coal-dust and are often much degenerated. Such coal-dust-laden leukocytes are especially abundant in anthracosis, where angular black particles, both intra- and extra-cellular, are often so numerous as to color the sputum (Plate II, Fig. 2, B). Occasionally mononuclear leukocytes are present.
Ordinary pus-cells are easily recognized in sputum stained by any of the methods already given. For eosinophilic cells, some method which includes eosin must be used. A simple method is to stain the dried and fixed film two or three minutes with saturated solution of eosin, and then one-half to one minute with LÖffler's methylene-blue; nuclei and bacteria will be blue, eosinophilic granules bright red. (2) Epithelial cells may come from any part of the (a) Squamous cells: large, flat, polygonal cells with a comparatively small nucleus (Fig. 13, i). They come from the upper air-passages, and are especially numerous in laryngitis and pharyngitis. They are frequently studded with bacteria—most commonly diplococci.
(b) Cylindric cells from the nose, trachea, and bronchi (Fig. 13, f, h): These are not usually abundant, and, (c) Alveolar cells: rather large, round, or oval cells with one or two round nuclei (Fig. 13). Their source is presumably the pulmonary alveoli. Like the leukocytes, they frequently contain particles of carbon (normal lung pigment). In chronic heart disease, owing to long-continued passive congestion, they may be filled with brown granules of altered blood-pigment, and are then called "heart-failure cells" (Plate II, Fig. 1). Alveolar cells commonly contain fat-droplets and, less frequently, myelin globules. The latter are colorless, rounded bodies, sometimes resembling fat droplets, but often showing concentric or irregularly spiral markings (Fig. 13, c, g). They are also found free in the sputum. They are abundant in the scanty morning sputum of apparently healthy persons, but may be present in any mucoid sputum. (3) Red blood-corpuscles may be present in small numbers in almost any sputum. When fairly constantly present in considerable numbers, they are suggestive of phthisis. The corpuscles when fresh are shown by any of the staining methods which include eosin. They are commonly so much degenerated as to be unrecognizable, and often only altered blood-pigment is left. Ordinarily, blood in the sputum is sufficiently recognized with the naked eye. Only those conditions which give fairly characteristic sputa are mentioned. 1. Acute Bronchitis.—There is at first a small amount of tenacious, almost purely mucoid sputum, frequently blood-streaked. This gradually becomes more abundant, 2. Chronic Bronchitis.—The sputum is usually abundant, mucopurulent, and yellowish or yellowish-green in color. Nummular masses—circular, "coin-like" discs which sink in water—may be seen. Microscopically, there are great numbers of leukocytes, often much degenerated. Epithelium is not abundant. Bacteria of various kinds, especially staphylococci, are usually numerous. In fibrinous bronchitis there are found, in addition, fibrinous casts, usually of medium size. In the chronic bronchitis accompanying long-continued passive congestion of the lungs, as in poorly compensated heart disease, the sputum may assume a rusty brown color, owing to presence of large numbers of the "heart-failure cells" previously mentioned. 3. Bronchiectasis.—The sputum is very abundant at intervals, sometimes as high as a liter in twenty-four hours, and has a very offensive odor when the cavity is large. It is thinner than that of chronic bronchitis, and upon standing separates into three layers of pus, mucus, and frothy serum. It contains great numbers of miscellaneous bacteria. 4. Gangrene of the Lung.—The sputum is abundant, fluid, very offensive, and brownish in color. It separates into three layers upon standing—a brown deposit, a clear fluid, and a frothy layer. Microscopically, few cells of any kind are found. Bacteria are extremely numerous; among them may sometimes be found an acid-fast bacillus probably identical with the smegma bacillus. As before 5. Pulmonary Edema.—Here there is an abundant, watery, frothy sputum, varying from faintly yellow or pink to dark-brown in color; a few leukocytes and epithelial cells and varying numbers of red blood-corpuscles are found with the microscope. 6. Bronchial Asthma.—The sputum during and following an attack is scanty and very tenacious. Most characteristic is the presence of Curschmann's spirals, Charcot-Leyden crystals, and eosinophilic leukocytes. 7. Croupous Pneumonia.—Characteristic of this disease is a scanty, rusty red, very tenacious sputum containing red corpuscles or altered blood-pigment, leukocytes, epithelial cells, usually many pneumococci, and often very small fibrinous casts. This sputum is seen during the stage of red hepatization. During resolution the sputum assumes the appearance of that of chronic bronchitis. When pneumonia occurs during the course of a chronic bronchitis, the characteristic rusty red sputum may not appear. 8. Pulmonary Tuberculosis.—The sputum is variable. In the earliest stages it may be scanty and almost purely mucoid, with an occasional yellow flake, or there may be only a very small mucopurulent mass. When the quantity is very small there may be no cough, the sputum reaching the larynx by action of the bronchial cilia. This is not well enough recognized by practitioners. A careful inspection of all the sputum brought up by the patient on several successive days, and a microscopic examination of all yellow portions, will not infrequently establish a diagnosis of tuberculosis when physical signs are negative. The sputum of more advanced cases resembles that of chronic bronchitis, with the addition of tubercle bacilli and elastic fibers. Caseous particles containing immense numbers of the bacilli are common. Far-advanced cases with large cavities often show rather firm, spheric or ovoid masses of thick pus in a thin fluid—the so-called "globular sputum." These globular masses usually contain many tubercle bacilli. CHAPTER IITHE URINEPreliminary Considerations.—The urine is an aqueous solution of various organic and inorganic substances. It is probably both a secretion and an excretion. Most of the substances in solution are either waste-products from the body metabolism or products derived directly from the foods eaten. Normally, the total amount of solid constituents carried off in twenty-four hours is about 60 gm., of which the organic substances make up about 35 gm. and the inorganic about 25 gm. The chief organic constituents are urea and uric acid. Urea constitutes about one-half of all the solids, or about 30 gm. in twenty-four hours. The chief inorganic constituents are the chlorids, phosphates, and sulphates. The chlorids, practically all in the form of sodium chlorid, constitute one-half, or about 13 gm., in twenty-four hours. Certain substances appear in the urine only in pathologic conditions. The most important of these are proteids, sugars, acetone and related substances, bile, hemoglobin, and the diazo substances. In addition to the substances in solution all urines contain various microscopic structures. While, under ordinary conditions, the composition of urine does not vary much from day to day, it varies greatly at different hours of the same day. It is evident, The urine must be examined while fresh. Decomposition sets in rapidly, especially in warm weather, and greatly interferes with all the examinations. Decomposition may be delayed by adding five grains of boric acid (as much of the powder as can be heaped upon a ten-cent piece) for each four ounces of urine. Formalin, in proportion of one drop to four ounces, is also an efficient preservative, but if larger amounts be used, it may give reactions for sugar and albumin, and is likely to cause a precipitate which greatly interferes with the microscopic examination. Normal and abnormal pigments, which interfere with certain of the tests, can be removed by filtering the urine through animal charcoal, or precipitating with a solution of acetate of lead and filtering. A suspected fluid can be identified as urine by detecting any considerable quantity of urea in it (p. 66). Traces of urea may, however, be met with in ovarian cyst fluid, while urine from very old cases of hydronephrosis may contain little or none. I. PHYSICAL EXAMINATION 1. Quantity.—The quantity passed in twenty-four hours varies greatly with the amount of liquids ingested, perspiration, etc. The normal may be taken as 1000 to 1500 c.c., or 40 to 50 ounces. The quantity is increased (polyuria) during absorption of large serous effusions and in many nervous conditions. It is usually much increased in chronic interstitial nephritis, diabetes insipidus, and diabetes mellitus. In these conditions a permanent increase in amount of urine is characteristic—a fact of much value in diagnosis. In diabetes mellitus the urine may, though rarely, reach the enormous amount of 50 liters. The quantity is decreased (oliguria) in severe diarrhea; in fevers; in all conditions which interfere with circulation in the kidney, as poorly compensated heart disease; and in the parenchymatous forms of nephritis. In uremia the urine is usually very greatly decreased and may be entirely suppressed (anuria). 2. Color.—This varies considerably in health, and depends largely upon the quantity of urine voided. The usual color is yellow or reddish-yellow, due to the presence of several pigments, chiefly urochrome. In recording the color Vogel's scale (see The color is sometimes greatly changed by abnormal 3. Transparency.—Freshly passed normal urine is clear. Upon standing, a faint cloud of mucus, leukocytes, and epithelial cells settles to the bottom. Abnormal cloudiness is usually due to presence of phosphates, urates, pus, blood, or bacteria. Amorphous phosphates are precipitated in neutral or alkaline urine. They form a white cloud and sediment which disappear upon addition of an acid. Amorphous urates are precipitated only in acid urine. They form a white or pink cloud and sediment ("brick-dust deposit") which disappear upon heating. Pus resembles amorphous phosphates to the naked eye. Its nature is easily recognized with the microscope, or by adding a strong solution of caustic soda to the sediment, which is thereby transformed into a gelatinous mass (DonnÉ's test). Bacteria, when present in great numbers, give a uniform cloud which cannot be removed by ordinary filtration. They are detected with the microscope. The cloudiness of decomposing urine is due mainly to precipitation of phosphates and multiplication of bacteria. 4. Reaction.—Normally, the mixed twenty-four-hour urine is slightly acid in reaction, the acidity being due to acid salts, not to free acids. Individual samples may be slightly alkaline, especially after a full meal. The reaction is determined by means of litmus paper. Acidity is increased after administration of certain drugs, and whenever the urine is concentrated from any cause, as in fevers. A very acid urine may cause frequent micturition because of its irritation. This is often an important factor in the troublesome enuresis of children. The urine always becomes alkaline upon long standing, owing to decomposition of urea with formation of ammonia. If markedly alkaline when voided, it usually indicates such "ammoniacal decomposition" in the bladder, which is the rule in chronic cystitis, especially that due to paralysis or obstruction. Alkalinity due to ammonia (volatile alkalinity) can be distinguished by the fact that litmus paper turned blue by the urine again becomes red upon gentle heating. Fixed alkalinity is due to alkaline salts, and is often observed during frequent vomiting, after the crisis of pneumonia, in various forms of anemia, after full meals, and after administration of certain drugs, especially salts of vegetable acids. 5. Specific Gravity.—The normal average is about Pathologically, it may vary from 1.001 to 1.060. It is low in chronic interstitial nephritis, diabetes insipidus, and many functional nervous disorders. It is high in fevers and in parenchymatous forms of nephritis. In any form of nephritis a sudden fall without a corresponding increase in quantity of urine may foretell approaching uremia. It is highest in diabetes mellitus. A high specific gravity when the urine is not highly colored should lead one to suspect this disease. A normal specific gravity does not, however, exclude it.
The specific gravity is most conveniently estimated by means of the urinometer—Squibb's is preferable (Fig. 14). It is standardized for a temperature of 77° F., and the urine should be at or near that temperature. Care should be taken that the urinometer does not touch the side of the tube, and that air-bubbles are removed from the surface One frequently wishes to ascertain the specific gravity of quantities of fluid too small to float an urinometer. A simple device for this purpose, which requires only about 3 c.c. and is very satisfactory in clinical work, has been designed by Saxe (Fig. 15). The urine is placed in the bulb at the bottom, the instrument is floated in distilled water, and the specific gravity is read off from the scale upon the stem.
6. Total Solids.—An estimation of the total amount of solids which pass through the kidneys in twenty-four hours is, in practice, one of the most useful of urinary In disease, the amount of solids depends mainly upon the activity of metabolism and the ability of the kidneys to excrete. An estimation of the solids, therefore, furnishes an important clue to the functional efficiency of the kidneys. The kidneys bear much the same relation to the organism as does the heart: they cause no direct harm so long as they are capable of performing the work required of them. When, however, through either organic disease or functional inactivity, they fail to carry off their proportion of the waste-products of the body, some of these products must either be eliminated through other organs, where they cause irritation and disease, or be retained within the body, where they act as poisons. The great importance of these poisons in production of distressing symptoms and even organic disease is not well enough recognized by most practitioners. Disappearance of unpleasant and perplexing symptoms as the urinary solids rise to the normal under proper treatment is often most surprising. When, other factors remaining unchanged, the amount of solids eliminated is considerably above the normal, increased destructive metabolism may be inferred. The total solids can be estimated roughly, but accurately enough for most clinical purposes, by multiplying the last two figures of the specific gravity of the mixed 7. Functional Tests.—Within the past few years much thought has been devoted to methods of more accurately ascertaining the functional efficiency of the kidneys, especially of one kidney when removal of the other is under consideration. The most promising of the methods which have been devised are cryoscopy, the methylene-blue test, and the phloridzin test. It is doubtful whether, except in experienced hands, these yield any more information than can be had from an intelligent consideration of the specific gravity and the twenty-four-hour quantity, together with a microscopic examination. They are most useful when the urines obtained from separate kidneys by segregation or ureteral catheterization are compared. The reader is referred to larger works upon urinalysis for details. Cryoscopy, determination of the freezing-point, depends upon the principle that the freezing-point of a fluid is depressed in proportion to the number of molecules in solution. To have any value, the freezing-point of the urine must be compared with that of the blood, since it is not so much the number of molecules contained in the urine as the number which the kidney has failed to carry off and has left in the blood, that indicates its insufficiency. The phloridzin test consists in the hypodermic injection of a small quantity of phloridzin. This substance is transformed into glucose by the kidneys of healthy persons. In disease, this change is more or less interfered with, and the amount of glucose recoverable from the urine is taken as an index of the secretory power of the kidneys. In applying these tests for "permeability," "secretory ability," etc., one must remember that the conditions are abnormal, and that there is no evidence that the kidneys will behave with the products of metabolism as they do with the substances selected for the tests, and also that the tests throw unusual work upon the kidneys, which in some cases may be harmful. II. CHEMIC EXAMINATION A. NORMAL CONSTITUENTS The most important are chlorids, phosphates, sulphates including indican, urea, and uric acid. 1. Chlorids.—These are derived from the food, and are mainly in the form of sodium chlorid. The amount excreted normally is 10 to 15 grams in twenty-four hours. It is much affected by the diet. Excretion of chlorids is diminished in nephritis and in fevers, especially in pneumonia and inflammations leading to the formation of large exudates. In nephritis the
Quantitative Estimation.—The best method for clinical purposes is the centrifugal method.
Purdy's Centrifugal Methods.—As shown by the late Dr. Purdy, the centrifuge offers an important means of making quantitative estimations of a number of substances in the urine. Results are easily and quickly obtained, and are probably accurate enough for all clinical purposes.
In general, the methods consist in precipitating the substance to be estimated in a graduated centrifuge tube, and applying a definite amount of centrifugal force for a definite length of time, after which the percentage of precipitate is read off upon the side of the tube. Albumin, if present, must be previously removed by boiling and filtering. Results are in terms of bulk of precipitate, which must not be confused with percentage by weight. The weight percentage can be found by referring to Purdy's tables, given later. In this, as in all quantitative urine work, percentages mean little in themselves; the actual The centrifuge should have an arm with radius of 6¾ inches when in motion, and should be capable of maintaining a speed of 1500 revolutions a minute. The electric centrifuge is to be recommended, although good work can be done with a water-power centrifuge, or, after a little practice, with the hand centrifuge. A speed indicator is desirable with electric and water-motor machines, although one can learn to estimate the speed by the musical note.
2. Phosphates.—Phosphates are derived largely from the food, only a small proportion resulting from metabolism. The normal daily output of phosphoric acid is about 2.5 to 3.5 gm. The urinary phosphates are of two kinds: alkaline, which make up two-thirds of the whole, and include the Quantitative estimation does not furnish much of definite clinical value. The centrifugal method is the most convenient.
3. Sulphates.—The urinary sulphates are derived partly from the food, especially meats, and partly from body metabolism. The normal output of sulphuric acid is about 1.5 to 3 gm. daily. Quantitative estimation of the total sulphates yields little of clinical value.
Potassium indoxyl sulphate, or indican, is derived from indol. Indol is absorbed and oxidized into indoxyl, which combines with potassium and sulphuric acid and is thus excreted. Under normal conditions the amount in the urine is small. It is increased by a meat diet. Pathologically, an increase of indican always indicates abnormal albuminous putrefaction somewhere in the body. It is noted in: (a) Diseases of the Small Intestine.—This is by far the most common source. Intestinal obstruction gives the largest amounts of indican. It is also much increased in intestinal indigestion—so-called "biliousness"; in inflammations, especially in cholera and typhoid fever; and in paralysis of peristalsis such as occurs in peritonitis. Simple constipation and diseases of the large intestine alone do not increase the amount of indican. (b) Diseases of the stomach associated with deficient hydrochloric acid, as chronic gastritis and gastric cancer. Diminished hydrochloric acid favors intestinal putrefaction. (c) Decomposition of exudates anywhere in the body, as in empyema, bronchiectasis, and large tuberculous cavities.
4. Urea.—From the standpoint of physiology urea is the most important constituent of the urine. It is the principal waste-product of metabolism, and constitutes about one-half of all the solids excreted—about 30 gm. in twenty-four hours. It represents 85 to 90 per cent. of the total nitrogen of the urine, and its quantitative estimation is a simple, though not very accurate, method of ascertaining the state of nitrogenous excretion. Normally, the amount is greatly influenced by exercise and diet. Pathologically, urea is increased in fevers, in diabetes, and especially during resolution of pneumonia and absorption of large exudates. Other factors being equal, the amount of urea indicates the activity of metabolism. In
Urea is decreased in diseases of the liver with destruction of liver substance. It may or may not be decreased in nephritis. In the early stages of chronic nephritis, when diagnosis is difficult, it is usually normal. In the late stages, when diagnosis is comparatively easy, it is decreased. Hence estimation of urea is of little help in the diagnosis of this disease, especially when, as is so frequently the case, a small quantity of urine taken at random is used. When, however, the diagnosis is established, estimations made at frequent intervals under the same conditions of diet and exercise are of much value, provided a sample of the mixed twenty-four-hour urine be used. A steady decline
The presence of urea can be shown by allowing a few drops of the fluid to partially evaporate upon a slide, and adding a small drop of pure colorless nitric acid or saturated solution of oxalic acid. Crystals of urea nitrate or oxalate (Fig. 19) will soon appear and can be recognized with the microscope. Quantitative Estimation.—The hypobromite method, which is generally used, depends upon the fact that urea is decomposed by sodium hypobromite with liberation of nitrogen. The amount of urea is calculated from the volume of nitrogen set free. The improved Doremus apparatus (Fig. 20) is the most convenient.
5. Uric Acid.—Uric acid is the most important of a group of substances, called purin bodies, which are derived chiefly from the nucleins of the food and from metabolic destruction of the nuclei of the body. The daily output of uric acid is about 0.4 to 1 gm. The amount of the other purin bodies together is about one-tenth that of uric acid. Excretion of these substances is greatly increased by a diet rich in nuclei, as sweetbreads and liver. Uric acid exists in the urine in the form of urates, which in concentrated urines are readily thrown out of solution and constitute the familiar sediment of "amorphous urates." This, together with the fact that uric acid is frequently deposited as crystals, constitutes its chief interest to the practitioner. It is a very common error to consider these deposits as evidence of excessive excretion. Pathologically, the greatest increase of uric acid occurs Quantitative Estimation.—The following are the best methods for ordinary clinical purposes, although no great accuracy can be claimed for them.
Those substances which appear in the urine only in pathologic conditions are of much more interest to the clinician than are those which have just been discussed. Among them are: proteids, sugars, the acetone bodies, bile, hemoglobin, and the diazo substances. The "pancreatic reaction" and detection of drugs in the urine will also be discussed under this head. 1. Proteids.—Of the proteids which may appear in the urine, serum-albumin and serum-globulin are the most important. Mucin, albumose, and a few others are found occasionally, but are of less interest. (1) Serum-albumin and Serum-globulin.—These two proteids constitute the so-called "urinary albumin." They usually occur together, have practically the same Their presence, or albuminuria, is probably the most important pathologic condition of the urine. It is either accidental or renal. The physician can make no greater mistake than to regard all cases of albuminuria as indicating kidney disease. Accidental or false albuminuria is due to admixture with the urine of albuminous fluids, such as pus, blood, and vaginal discharge. The microscope will usually reveal its nature. Renal albuminuria refers to albumin which has passed from the blood into the urine through the walls of the kidney tubules or the glomeruli. It probably never occurs as a physiologic condition, the so-called "functional albuminuria" being due to obscure or slight pathologic changes. Renal albuminuria may be referred to one or more of the following causes. In practically all cases it is accompanied by tube-casts. (a) Changes in the blood which render its albumin more diffusible, as in severe anemias, purpura, and scurvy. Here the albumin is small in amount. (b) Changes in circulation in the kidney, either anemia or congestion, as in excessive exercise, chronic heart disease, and pressure upon the renal veins. The quantity of albumin is usually, but not always, small. Its presence is constant or temporary, according to the cause. Most of the causes, if continued, will produce organic changes in the kidney. (c) Organic Changes in the Kidney.—These include the inflammatory and degenerative changes commonly grouped Detection of albumin depends upon its coagulation by chemicals or heat. There are many tests, but none is entirely satisfactory, because other substances as well as albumin are precipitated. The most common source of error is mucin. The tests given here are widely used and can be recommended. They make no distinction between serum-albumin and serum-globulin. They are given as nearly as possible in order of their delicacy. It is very important that urine to be tested for albumin be rendered clear by filtration or centrifugation. This is too often neglected in routine work. When ordinary methods do not suffice, it can usually be cleared by shaking up with a little magnesium carbonate and filtering.
Quantitative Estimation.—The gravimetric, which is the most reliable method, is too elaborate for clinical work. Both Esbach's, which is very widely used, and the centrifugal method give fair results.
(3) Albumoses.—These are intermediate products in the digestion of proteids. They have been observed in the urine in febrile and malignant diseases and chronic suppurations, but their clinical significance is indefinite. The following is a simple test: Mix equal parts of the urine, which has been strongly acidified with acetic acid, and a saturated solution of sodium chlorid. A white cloud, which appears upon moderate heating and disappears upon boiling, shows the presence of albumose. If the cloud increases upon boiling, albumin is present and should be removed by filtering while hot. The cloud due to albumose will reappear as the filtrate cools. 2. Sugars.—Various sugars may at times be found in the urine. Glucose is by far the most common, and is the only one of clinical importance. Levulose, lactose, and some others are occasionally met with. (1) Glucose (Dextrose).—It is probable that traces of glucose, too small to respond to the ordinary tests, are present in the urine in health. Its presence in appreciable amount constitutes "glycosuria." Transitory glycosuria is unimportant, and may occur in many conditions, as after general anesthesia and Persistent glycosuria has been noted in brain injuries involving the floor of the fourth ventricle. As a rule, however, persistent glycosuria is diagnostic of diabetes mellitus, of which disease it is the essential symptom. The amount of glucose eliminated in diabetes is usually considerable, and is sometimes very large, reaching 500 gm., or even more in twenty-four hours, but it does not bear any uniform relation to the severity of the disease. Glucose may, on the other hand, be almost or entirely absent temporarily. Detection of Glucose.—If albumin be present in more than traces, it must be removed by boiling and filtering.
Quantitative Estimation.—In quantitative work Fehling's solution, for so many years the standard, has been largely displaced by Purdy's, which avoids the heavy precipitate that so greatly obscures the end-reaction in Fehling's method. The older method is still preferred by many, and both are, therefore, given. Should the urine contain much glucose, it must be diluted before making any quantitative test, allowance being made for the dilution in the subsequent calculation. Albumin, if present, must be removed by acidifying a considerable quantity of urine with acetic acid, boiling, and filtering. The precipitate should then be washed with water and the washings added to the urine to bring it to its original volume.
(2) Levulose, or fruit-sugar, is very rarely present in the urine except in association with glucose, and has about the same significance. Its name is derived from the fact that it rotates polarized light to the left. It behaves the same as glucose with all the ordinary tests, and can be distinguished only by polarization. (3) Lactose, or milk-sugar, is sometimes present in the urine of nursing women and in that of women who have recently miscarried. It is of interest chiefly because it may be mistaken for glucose. It reduces copper, but does not ferment with yeast. In strong solution it can form crystals with phenylhydrazin, but is extremely unlikely to do so when the test is applied directly to the urine. 3. Acetone Bodies.—This is a group of closely related substances—acetone, diacetic acid, and beta-oxybutyric (1) Acetone.—Minute traces, too small for the ordinary tests, may be present in the urine under normal conditions. Larger amounts are not uncommon in fevers, gastrointestinal disturbances, and certain nervous disorders. Occurrence of acetonuria in pregnancy suggests death of the fetus. Acetonuria is practically always observed in acid intoxication, and, together with diaceturia, constitutes its most significant diagnostic sign. A similar or identical toxic condition, always accompanied by acetonuria and often fatal, is now being recognized as a not infrequent late effect of anesthesia, particularly of chloroform anesthesia. This postanesthetic toxemia is more likely to appear, and is more severe when the urine contains any notable amount of acetone before operation, which suggests the importance of routine examination for acetone in surgical cases. Acetone is present in considerable amounts in many cases of diabetes mellitus, and is always present in severe
Detection of Acetone.—The urine may be tested directly, but it is best to distil it after adding a little phosphoric or hydrochloric acid to prevent foaming, and to test the first few cubic centimeters of distillate. A simple distilling apparatus is shown in Fig. 26. The test-tube may be attached to the delivery tube by means of a two-hole rubber cork as shown, the second hole serving as air vent, or, what is much less satisfactory, it may be tied in place with a string. Should the vapor not condense well, the test-tube may be immersed in a glass of cold water.
(2) Diacetic acid occurs in the same conditions as acetone, but is less frequent and has more serious significance. In diabetes its presence is a grave symptom and often forewarns of approaching coma. It rarely or never occurs without acetone. Detection.—The urine must be fresh.
4. Bile.—Bile appears in the urine in all diseases which produce jaundice, often some days before the skin becomes yellow; and in many disorders of the liver not severe enough to cause jaundice. It also occurs in diseases with extensive and rapid destruction of red blood-corpuscles. Both bile-pigment and bile acids may be found. They generally occur together, but the pigment is not infrequently present alone. Bilirubin, only, occurs in freshly voided urine, the other pigments (biliverdin, bilifuscin, etc.) being produced from this by oxidation as the urine stands. The acids are almost never present without the pigments, and are, therefore, seldom tested for clinically. Detection of Bile-pigment.—Bile-pigment gives the urine a greenish-yellow, yellow, or brown color, which upon shaking is imparted to the foam. Cells, casts, and other structures in the sediment may be stained brown or yellow. This, however, should not be accepted as proving the presence of bile without further tests.
Detection of Bile Acids.—Hay's test is simple, sensitive, and fairly reliable, and will, therefore, appeal to the practitioner. It depends upon the fact that bile acids lower surface tension. Other tests require isolation of the acids for any degree of accuracy.
5. Hemoglobin.—The presence in the urine of hemoglobin or pigments directly derived from it, accompanied by few, if any, red corpuscles, constitutes hemoglobinuria. It is a rare condition, and must be distinguished from hematuria, or blood in the urine, which is common. In both conditions chemic tests will show hemoglobin, but in the latter the microscope will reveal the presence of red corpuscles. Urines which contain notable amounts of hemoglobin have a reddish or brown color, and may deposit a sediment of brown, granular pigment. Hemoglobinuria occurs when there is such extensive destruction of red blood-cells within the body that the liver cannot transform all the hemoglobin set free into bile-pigment. The most important examples are seen in Detection.—Teichmann's test (p. 202) may be applied to the precipitate after boiling and filtering, but the guaiac test is more convenient in routine work.
6. Diazo Substances.—Certain unknown substances sometimes present in the urine give a characteristic color reaction—the "diazo reaction" of Ehrlich—when treated with diazo-benzol-sulphonic acid and ammonia. This reaction has much clinical value provided its limitations (1) Typhoid Fever.—Practically all cases give a positive reaction, which varies in intensity with the severity of the disease. It is so constantly present that it may be said to be "negatively pathognomonic": if negative at a stage of the disease when it should be positive, typhoid is almost certainly absent. Upon the other hand, a reaction when the urine is highly diluted (1:50 or more) has much positive diagnostic value, since this dilution prevents the reaction in most conditions which might be mistaken for typhoid; but it should be noted that mild cases of typhoid may not give it at this dilution. Ordinarily the diazo appears a little earlier than the Widal reaction—about the fourth or fifth day—but it may be delayed. In contrast to the Widal, it begins to fade about the end of the second week, and soon thereafter entirely disappears. An early disappearance is a favorable sign. It reappears during a relapse, and thus helps to distinguish between a relapse and a complication, in which it does not reappear. (2) Tuberculosis.—The diazo reaction has been obtained in many forms of the disease. It has little or no diagnostic value. Its continued presence in pulmonary tuberculosis is, however, a grave prognostic sign, even when the physical signs are slight. After it once appears it generally persists more or less intermittently until death, the average length of life after its appearance being about six months. The reaction is often temporarily present in (3) Measles.—A positive reaction is frequently obtained in measles, and may help to distinguish this disease from German measles, in which it does not occur.
7. Pancreatic Reaction.—Cammidge has shown that in cases of pancreatitis a substance capable of forming
Acetanilid and Phenacetin.—The urine is evaporated by gentle heat to about half its volume, boiled for a few minutes with about one-fifth its volume of strong hydrochloric acid, and shaken out with ether. The ether is evaporated, the residue dissolved in water, and the following test applied: To about 10 c.c. are added a few cubic centimeters of 3 per cent. phenol, followed by a weak solution of chromium trioxid (chromic acid) drop by drop. The fluid assumes a red color, which changes to blue when ammonia is added. If the urine is very pale, extraction with ether may be omitted. Antipyrin.—This drug gives a dark-red color when a few drops of 10 per cent. ferric chlorid are added to the urine. The color does not disappear upon boiling, which excludes diacetic acid. Arsenic.—Reinsch's Test.—Add to the urine in a test-tube or small flask about one-seventh its volume of hydrochloric acid, introduce a piece of bright copper-foil about one-eighth-inch square, and boil for several minutes. If arsenic be present, a dark-gray film is deposited upon the copper. The test is more delicate if the urine be concentrated by slow evaporation. This test is well known and is widely used, but is not so reliable as the following: Gutzeit's Test.—In a large test-tube place a little Atropin will cause dilatation of the pupil when a few drops of the urine are placed in the eye of a cat or rabbit. Bromids can be detected by acidifying about 10 c.c. of the urine with dilute sulphuric acid, adding a few drops of fuming nitric acid and a few cubic centimeters of chloroform, and shaking. In the presence of bromin the chloroform, which settles to the bottom, assumes a yellow color. Iodin—from ingestion of iodids or absorption from iodoform dressings—is tested for in the same way as the bromids, the chloroform assuming a pink to reddish-violet color. To detect traces, a large quantity of urine should be rendered alkaline with sodium carbonate and greatly concentrated by evaporation before testing. Lead.—No simple method is sufficiently sensitive to detect the traces of lead which occur in the urine in chronic poisoning. Of the more sensitive methods, that of Arthur Lederer is probably best suited to the practitioner: It is essential that all apparatus used be lead-free. Five hundred cubic centimeters of the urine are acidified The mixture is then filtered through a small, close-grained filter-paper (preferably an ashless, quantitative filter-paper), and any sediment remaining in the beaker or dish is carefully washed out with alcohol and filtered. A test-tube is placed underneath the funnel; a hole is punched through the tip of the filter with a small glass rod, and all the precipitate (which may be so slight as to be scarcely visible) washed down into the test-tube with a jet of distilled water from a wash-bottle, using as little water as possible. Ten cubic centimeters will usually suffice. This fluid is then heated, adding crystals of sodium acetate until it becomes perfectly clear. It now contains all the lead of the 500 c.c. urine in the form of lead acetate. It is allowed to cool, and hydrogen sulphid gas is passed through it for about five minutes. The slightest yellowish-brown discoloration indicates the presence of lead. A very slight discoloration can be best seen when looked at from above. For comparison, the gas may be passed through a test-tube containing an equal amount of distilled water. The quantity of lead can be
Mercury.—Traces can be detected in the urine for a considerable time after the use of mercury compounds by ingestion or inunction. About a liter of urine is acidified with 10 c.c. hydrochloric acid, and a small piece of copper-foil or gauze is introduced. This is gently heated for an hour, and allowed to stand for twenty-four hours. The metal is then removed, and washed successively with very dilute sodium hydroxid solution, alcohol, and ether. When dry, Morphin.—Add sufficient ammonia to the urine to render it distinctly ammoniacal, and shake thoroughly with a considerable quantity of pure acetic ether. Separate the ether and evaporate to dryness. To a little of the residue in a watch-glass or porcelain dish add a few drops of formaldehyd-sulphuric acid, which has been freshly prepared by adding one drop of formalin to 1 c.c. pure concentrated sulphuric acid. If morphin be present, this will produce a purple-red color, which changes to violet, blue-violet, and finally nearly pure blue. Phenol.—As has been stated, the urine following phenol poisoning turns olive-green and then brownish-black upon standing. Tests are of value in recognizing poisoning from ingestion and in detecting absorption from carbolized dressings. The urine is acidulated with hydrochloric acid and distilled. To the first few cubic centimeters of distillate is added 10 per cent. solution of ferric chlorid drop by drop. The presence of phenol causes a deep amethyst-blue color, as in Uffelmann's test for lactic acid. Phenolphthalein, which is now being used as a cathartic under the name of purgen, gives a bright pink color when the urine is rendered alkaline with caustic soda. The remainder of the residue may be dissolved in a little dilute sulphuric acid. This solution will show a characteristic blue fluorescence when quinin is present. Resinous drugs cause a white precipitate like that of albumin when strong nitric acid is added to the urine. This is dissolved by alcohol. Salicylates, salol, and similar drugs give a bluish-violet color, which disappears upon heating, upon addition of a few drops of 10 per cent. ferric chlorid solution. When the quantity of salicylates is small, the urine may be acidified with hydrochloric acid and extracted with ether, the ether evaporated, and the test applied to an aqueous solution of the residue. Tannin and its compounds appear in the urine as gallic acid, and the urine becomes greenish-black (inky, if much gallic acid be present) when treated with a solution of ferric chlorid. A careful microscopic examination will often detect structures of great diagnostic importance in urine which seems perfectly clear, and from which only very slight Since the nature of the sediment soon changes, the urine must be examined while fresh, preferably within six hours after it is voided. The sediment is best obtained by means of the centrifuge. If a centrifuge is not available, the urine may be allowed to stand in a conical test-glass for six to twenty-four hours after adding some preservative (p. 48). The "torfuge" (Fig. 31) is said to be a very satisfactory substitute for the centrifuge, and is readily portable.
A small amount of the sediment should be transferred to a slide by means of a pipet. It is very important to do this properly. The best pipet is a small glass tube which has been drawn out at one end to a tip with rather small opening. The tube or glass containing the sediment is held on a level with the eye, the larger end of the pipet is closed with the index-finger, which must be dry, and the In examining urinary sediments microscopically no fault is so common, nor so fatal to good results, as improper illumination (see Figs. 2 and 3), and none is so easily corrected. The light must be central and very subdued. The two-thirds objective should be used as a finder, while the one-sixth is reserved for examining details. It is well to emphasize that the most common errors which result in failure to find important structures, when present, are lack of care in transferring the sediment to the slide, too strong illumination, and too great magnification. Urinary sediments may be studied under three heads: A. Unorganized sediments. B. Organized sediments. C. Extraneous structures. A. UNORGANIZED SEDIMENTS In general these have little diagnostic or prognostic significance. Most of them are substances normally present which have been precipitated from solution either because present in excessive amounts or, more frequently, because of some alteration in the urine (as in reaction, concentration, etc.) which may be purely physiologic, depending upon changes in diet or habits. Various substances are always precipitated during decomposition, which may take place either within or without the body. Unorganized sediments may be classified according to the reaction of the urine in which they are most likely to be found: In acid urine: uric acid, amorphous urates, sodium urate, calcium oxalate, leucin and tyrosin, cystin, and fat-globules. Uric acid, the urates, and calcium oxalate are In alkaline urine: phosphates, calcium carbonate, and ammonium urate. Other crystalline sediments (Fig. 32) which are rare and require no further mention are: calcium sulphate, cholesterin, hippuric acid, hematoidin, fatty acids, and indigo.
1. In Acid Urine.—(1) Uric-acid Crystals.—These crystals are the red grains—"gravel" or "red sand"—which are often seen adhering to the sides and bottom of a vessel containing urine. Microscopically, they are yellow or reddish-brown crystals, which differ greatly in size and shape. The most characteristic forms (Plate III and Fig. 33) are "whetstones"; roset-like clusters of prisms and whetstones; and rhombic plates, which have usually a paler color than the other forms and are sometimes colorless. Recognition of the crystals depends less upon their shape than upon their color, the reaction of the urine, and the facts that they are soluble in caustic soda solution and insoluble in hydrochloric or acetic acid.
A deposit of uric-acid crystals has no significance unless it occurs before or very soon after the urine is voided. Every urine, if kept acid, will in time deposit its uric acid. Factors which favor an early deposit are high acidity, diminished urinary pigments, and excessive excretion of uric acid. The chief clinical interest of the crystals lies in their tendency to form calculi, owing to the readiness with which they collect about any solid object. Their presence in the freshly voided urine in clusters of crystals suggests stone in the kidney or bladder, especially if blood is also present (see Fig. 62). (2) Amorphous Urates.—These are chiefly urates of Rarely, sodium urate occurs in crystalline form—slender prisms, arranged in fan- or sheaf-like structures (Fig. 32). (3) Calcium Oxalate.—Characteristic of calcium oxalate are colorless, glistening, octahedral crystals, giving the appearance of small squares crossed by two intersecting diagonal lines—the so-called "envelop crystals" (Fig. 47). They vary greatly in size, being sometimes so small as to seem mere points of light with medium-power objectives. Unusual forms, which, however, seldom occur except in conjunction with the octahedra, are colorless dumb-bells, spheres, and variations of the octahedra (Fig. 34). The spheres might be mistaken for globules of fat or red blood-corpuscles. Crystals of calcium oxalate are insoluble in acetic acid or caustic soda. They are dissolved by strong hydrochloric acid, and recrystallize as octahedra upon addition of ammonia. They are sometimes encountered in alkaline urine.
The crystals are commonly found in the urine after ingestion of vegetables rich in oxalic acid, as tomatoes, (4) Leucin and Tyrosin.—-Crystals are deposited only when the substances are present in considerable amount. When present in smaller amount, they will usually be deposited if a drop of the urine be slowly evaporated upon a slide. They generally appear together, and are of rare occurrence, usually indicating severe fatty destruction of the liver, such as occurs in acute yellow atrophy and phosphorus-poisoning. The crystals cannot be identified from their morphology alone, since other substances, notably calcium phosphate (Fig. 38) and ammonium urate, may take similar or identical forms. Leucin crystals (Fig. 35) are slightly yellow, oily-looking spheres, many of them with radial and concentric
Tyrosin crystallizes in very fine colorless needles, usually arranged in sheaves, with a marked constriction at the middle (Fig. 35). It is soluble in ammonia and hydrochloric acid, but not in acetic acid.
(5) Cystin crystals are colorless, highly refractive, rather thick, hexagonal plates with well-defined edges. They lie either singly or superimposed to form more or less irregular clusters (Fig. 36). Uric acid sometimes Cystin crystals are very rare, and when found, point to cystin calculus. (6) Fat-globules.—Fat appears in the urine as highly refractive globules of various sizes, frequently very small. These globules are easily recognized from the fact that they are stained black by osmic acid and red by Sudan III. The stain may be applied upon the slide, as already described (p. 103). Osmic acid should be used in 1 per cent. aqueous solution; Sudan III in saturated solution in 70 per cent. alcohol. Fat in the urine is usually a contamination from unclean vessels, oiled catheters, etc. A very small amount may be present after ingestion of large quantities of cod-liver oil or other fats. In fatty degeneration of the kidney, as in phosphorus-poisoning and chronic parenchymatous nephritis, fat-globules are commonly seen, both free in the urine and embedded in cells and tube-casts. In chyluria, or admixture of chyle with the urine as a result of rupture of a lymph-vessel, minute droplets of fat are so numerous as to give the urine a milky appearance. Chyluria occurs most frequently as a symptom of infection by Filaria sanguinis hominis. 2. In Alkaline Urine.—(1) Phosphates.—While most common in alkaline urine, phosphates are sometimes deposited in neutral or feebly acid urines. The usual forms are: (a) Ammoniomagnesium phosphate crystals; (b) acid calcium phosphate crystals; and (c) amorphous phosphates. All are readily soluble in acetic acid. (a) Ammoniomagnesium Phosphate Crystals.—They are
When rapidly deposited, as by artificial precipitation, triple phosphate often takes feathery, star- or leaf-like forms. These gradually develop into the more common prisms. X-forms may be produced by partial solution of prisms. (b) Acid Calcium Phosphate Crystals.—In feebly add, neutral, or feebly alkaline urines acid calcium phosphate, wrongly called "neutral calcium phosphate," is not infrequently deposited in the form of colorless prisms Calcium phosphate often forms large, thin, irregular, usually granular, colorless plates, which are easily recognized (Fig. 38, 3).
(c) Amorphous Phosphates.—The earthy phosphates are thrown out of solution in most alkaline and many neutral urines as a white, amorphous sediment, which may be mistaken for pus macroscopically. Under the microscope the sediment is seen to consist of numerous colorless granules, distinguished from amorphous urates by their color, their solubility in acetic acid, and the reaction of the urine. The various phosphatic deposits frequently occur together. They are sometimes due to excessive excretion of phosphoric acid, but usually merely indicate that the urine has become, or is becoming, alkaline.
(3) Ammonium Urate Crystals.—This is the only urate deposited in alkaline urine. It forms opaque yellow crystals, usually in the form of spheres (Plate IV, and Fig. 63), which are often covered with fine or coarse spicules, "thorn-apple crystals." Sometimes dumb-bells, compact sheaves of fine needles, and irregular rhizome forms are seen (Fig. 40). Upon addition of acetic acid they dissolve, and rhombic plates of uric acid appear.
B. ORGANIZED SEDIMENTS The principal organized structures in urinary sediments are: tube-casts; epithelial cells; pus-corpuscles; red blood-corpuscles; spermatozoa; bacteria; and animal parasites. They are much more important than the unorganized sediments just considered. 1. Tube-casts.—These interesting structures are albuminous molds of the uriniferous tubules. Their presence in the urine probably always indicates some pathologic change in the kidney, although this change may be very slight or transitory. Large numbers may be present in temporary irritations and congestions. They do not in themselves, therefore, imply organic disease of the kidney. They probably occur only in urine which contains, or has recently contained, albumin. While it is not possible to draw a sharp dividing-line between the different varieties, casts may be classified as: (1) Hyaline casts; (2) waxy casts; (3) granular casts; (4) fatty casts; (5) casts containing organized structures—(a) epithelial casts; (b) blood-casts; (c) pus-casts; (d) bacterial casts. As will be seen, practically all varieties are modifications of the hyaline. The significance of the different varieties is more readily understood if one considers their mode of formation. Albuminous material, the source and nature of which are not definitely known, probably enters the lumen of a uriniferous tubule in a fluid or plastic state. It there hardens into a mold, which, when washed out by the The search for casts must be carefully made. The urine must be fresh, since hyaline casts soon dissolve when it becomes alkaline. It should be thoroughly centrifugalized. When the sediment is abundant, casts, being light structures, will be found near the top. In cystitis, where casts may be entirely hidden by the pus, the bladder should be irrigated to remove as much of the pus as possible and the next urine examined. In order to prevent solution of the casts the urine, if alkaline, must be rendered acid by previous administration of boric acid or other drugs. (1) Hyaline Casts.—Typically, these are colorless, homogeneous, semitransparent, cylindric structures, with parallel sides and usually rounded ends. Not infrequently they are more opaque or show a few granules or an occasional cell, either adhering to them or contained within their substance. Generally they are straight or curved; less commonly, convoluted. Their length and breadth vary greatly: they are sometimes so long as to extend across several fields of a medium-power objective, but are usually much shorter; in breadth, they vary from one to seven or eight times the diameter of a red blood-corpuscle. (See Figs. 2, 41, 42, and 46.)
Hyaline casts are the least significant of all the casts, Very broad hyaline casts commonly indicate complete desquamation of the tubular epithelium, such as occurs in the late stages of nephritis. (2) Waxy Casts.—Like hyaline casts, these are homogeneous when typical, but frequently contain a few granules or an occasional cell. They are much more opaque than the hyaline variety, and are usually shorter and broader, with irregular, broken ends, and sometimes appear to be segmented. They are grayish or colorless, and have a dull waxy look, as if cut from paraffin (Figs. 43 and 61). They are sometimes composed of material which gives the amyloid reactions. Waxy casts are found in most advanced cases of nephritis, where they are an unfavorable sign.
Casts which resemble waxy casts but have a distinctly (3) Granular Casts.—These are merely hyaline casts in which numerous granules are embedded (Figs. 42, 44, 46, and 61). Finely granular casts contain many fine granules, are usually shorter, broader, and more opaque than the hyaline variety, and are more conspicuous. Their color is grayish or pale yellow.
Coarsely granular casts contain larger granules and are darker in color than the finely granular, being often dark brown owing to presence of altered blood-pigment. They are usually shorter and more irregular in outline, and more frequently have irregularly broken ends. (4) Fatty Casts.—Small droplets of fat may at times be seen in any variety of cast. Those in which the droplets are numerous are called fatty casts (Figs. 43 and 44). The fat-globules are not difficult to recognize. Staining with osmic acid or Sudan (p. 109) will remove any doubt as to their nature. (5) Casts Containing Organized Structures.—Cells and other structures are frequently seen adherent to a cast or embedded within it. (See Figs. 41 and 42). When numerous, they give name to the cast. (a) Epithelial casts contain epithelial cells from the renal tubules. They always imply desquamation of epithelium, which rarely occurs except in parenchymatous inflammations (Figs. 60 and 61).
(b) Blood-casts contain red blood-corpuscles, usually much degenerated (Figs. 45 and 60). They always indicate hemorrhage into the tubules, which is most (c) Pus-casts (see Fig. 62), composed almost wholly of pus-corpuscles, are uncommon, and point to a chronic suppurative process in the kidney. (d) True bacterial casts are rare. They indicate a septic condition in the kidney. Bacteria may permeate a cast after the urine is voided.
The structures most likely to be mistaken for casts are: (1) Mucous Threads.—Mucus frequently appears in the form of long strands which slightly resemble hyaline casts (Fig. 46). They are, however, more ribbon-like, have less well-defined edges, and usually show faint longitudinal striations. Their ends taper to a point or are split or curled upon themselves, and are never evenly rounded, as is commonly the case with hyaline casts. (2) Cylindroids.—This name is sometimes given to the (3) Masses of amorphous urates or phosphates or very small crystals (Fig. 47), which accidentally take a cylindric form, or shreds of mucus covered with granules, closely resemble granular casts. Application of gentle heat or appropriate chemicals will serve to differentiate them. When urine contains both mucus and granules, large numbers of these "pseudo-casts," all lying in the same direction, can be produced by slightly moving the cover-glass from side to side. It is possible—as in urate infarcts of infants—for urates to be molded into cylindric bodies within the renal tubules.
(4) Hairs and fibers of wool, cotton, etc. These could be mistaken for casts only by beginners. One can easily
(5) HyphÆ of molds are not infrequently mistaken for hyaline casts. Their higher degree of refraction, their jointed or branching structure, and the accompanying spores will differentiate them (Fig. 58). 2. Epithelial Cells.—A few cells from various parts of the urinary tract occur in every urine. A marked increase indicates some pathologic condition at the site of their origin. It is sometimes, but by no means always, possible to locate their source from their form. Any epithelial cell may be so granular from degenerative changes that the nucleus is obscured. They are usually divided into three groups: (1) Small, round, or polyhedral cells are about the size of pus-corpuscles, or a little larger, with a single round nucleus. Such cells may come from the deeper layers of any part of the urinary tract. They are uncommon in normal urine. When they are dark in color, very granular, and contain a comparatively large nucleus, they probably come from the renal tubules, but their origin in the kidney is not proved unless they are found embedded in casts. Renal cells are abundant in parenchymatous nephritis, especially the acute form. They are nearly always fatty—most markedly so in chronic parenchymatous nephritis, where their (2) Irregular cells are considerably larger than the preceding. They are round, pear-shaped, or spindle-shaped, or may have tail-like processes, and are hence named large round, pyriform, spindle, or caudate cells respectively. Each contains a round or oval distinct nucleus. Their usual source is the deeper layers of the urinary tract, especially of the bladder. Caudate forms come most commonly from the pelvis of the kidney (see Figs. 49, b, 50, 62, and 63).
(3) Squamous or pavement cells are large flat cells, each with a small, distinct, round or oval nucleus (Fig. 49, a). They are derived from the superficial layers of the ureters, bladder, urethra, or vagina. Those from the bladder are generally rounded, while those from the vagina are larger, thinner, and more angular. Great numbers of these vaginal cells, together with pus-corpuscles, may be present when leukorrhea exists.
3. Pus-corpuscles.—A very few leukocytes are present in normal urine. They are more abundant when mucus is present. An excess of leukocytes, mainly of the polymorphonuclear variety, with albumin, constitutes pyuria—pus in the urine. When at all abundant, pus forms a white sediment resembling amorphous phosphates macroscopically. Under the microscope the corpuscles appear as very granular cells, about twice the diameter of a red blood-corpuscle (Figs. 51 and 63). In freshly voided urine many exhibit ameboid motion, assuming irregular outlines. Each contains one irregular nucleus or several small, rounded nuclei. The nuclei are obscured or entirely hidden by the granules, but may be brought clearly into view by running a little acetic acid under the cover-glass. This enables one to easily distinguish pus-corpuscles from small round epithelial cells, which resemble them in size, but have a single, rather large, round nucleus. Pyuria indicates suppuration in some part of the urinary A fairly accurate idea of the quantity of pus from day to day may be had by shaking the urine thoroughly and counting the number of corpuscles per cubic millimeter upon the Thoma-Zeiss blood-counting slide.
4. Red Blood-corpuscles.—Urine which contains blood is always albuminous. Very small amounts do not alter its macroscopic appearance. Larger amounts alter it considerably. Blood from the kidneys is generally intimately mixed with the urine and gives it a hazy reddish or brown color. When from the lower urinary tract, it is not so intimately mixed, and settles more quickly to the bottom, the color is brighter, and small clots are often present. Red blood-corpuscles are not usually difficult to recognize with the microscope. When very fresh, they have a normal appearance, being yellowish discs of uniform size (normal blood). When they have been in the urine any
When not due to contamination from menstrual discharge, blood in the urine, or hematuria, is always pathologic. Blood comes from the kidney tubules in severe hyperemia, in some forms of nephritis, and in renal tuberculosis and malignant disease. The finding of blood-casts is the only certain means of diagnosing the kidney as its source. Blood comes from the pelvis of the kidney in renal calculus (Fig. 62), and is then usually intermittent, small in amount, and accompanied by a little pus and perhaps crystals of the substance forming the stone. Considerable hemorrhages from the bladder may occur in vesical calculus, tuberculosis, and newgrowths. Small amounts of blood generally accompany acute cystitis. 5. Spermatozoa are generally present in the urine of men after nocturnal emissions, after epileptic convulsions, and in spermatorrhea. They may be found in the urine of both sexes following coitus. They are easily recognized
6. Bacteria.—Normal urine is free from bacteria in the bladder, but becomes contaminated in passing through the urethra. Various non-pathogenic bacteria, notably Micrococcus ureÆ (Fig. 54), are always present in decomposing urine. In suppurations of the urinary tract pus-producing organisms may be found. In many infectious diseases the specific germs may be eliminated in Bacteria produce a cloudiness which will not clear upon filtration. They are easily seen with the one-sixth objective in the routine microscopic examination. Ordinarily, no attempt is made to identify any but the tubercle bacillus and the gonococcus. Tubercle bacilli are nearly always present in the urine when tuberculosis exists in any part of the urinary tract, but are often difficult to find, especially when the urine contains little or no pus.
In gonorrhoea gonococci are sometimes found in the sediment, but more commonly in the "gonorrheal threads," or "floaters." In themselves, these threads are by no means diagnostic of gonorrhea. Detection of the gonococcus is described later (p. 264).
7. Animal parasites are rare in the urine. Hooklets and scolices of TÆnia echinococcus (Fig. 55) and embryos of Filaria sanguinis hominis have been met. In Africa the ova, and even adults, of Distoma hÆmatobium are common, accompanying "Egyptian hematuria."
Other parasites, most of which are described in Chapter VI, may be present from contaminations. A worm The laboratory worker must familiarize himself with the microscopic appearance of the more common of the numerous structures which may be present from accidental contamination (Fig. 57).
Yeast-cells are smooth, colorless, highly refractive, spheric or ovoid cells. They sometimes reach the size of Mold fungi (Fig. 58) are characterized by refractive, jointed, or branched rods (hyphÆ), often arranged in a network, and by highly refractive, spheric or ovoid spores. They are common in urine which has stood exposed to the air.
Fibers of wool, cotton, linen, or silk, derived from towels, the clothing of the patient, or the dust in the air are present in almost every urine. Fat-droplets are most frequently derived from unclean bottles or oiled catheters. Starch-granules may reach the urine from towels, the
IV. THE URINE IN DISEASE In this section the characteristics of the urine in those diseases which produce distinctive urinary changes will be briefly reviewed. 1. Renal Hyperemia.—Active hyperemia is usually an early stage of acute nephritis, but may occur independently as a result of temporary irritation. The urine is generally decreased in quantity, highly colored, and strongly acid. Albumin is always present—usually in traces only, but sometimes in considerable amount for a day or two. The sediment contains a few hyaline and finely granular casts and an occasional red blood-cell. In very severe hyperemia the urine approaches that of acute nephritis.
Passive hyperemia occurs most commonly in diseases of the heart and liver and in pregnancy. The quantity of urine is somewhat low and the color high, except in pregnancy. Albumin is present in small amount only. The sediment contains a very few hyaline or finely granular 2. Nephritis.—The various degenerative and inflammatory conditions grouped under the name of nephritis have certain features in common. The urine in all cases contains albumin and tube-casts, and in all well-marked cases shows a decrease of normal solids, especially of urea and the chlorids. The characteristics of the different forms are well shown in the table on opposite page, modified from Hill.
3. Renal Tuberculosis.—The urine is pale, usually cloudy. The quantity may not be affected, but is apt to be increased. In early cases the reaction is faintly acid and there are traces of albumin and a few renal cells. In advanced cases the urine is alkaline, has an offensive odor, and is irritating to the bladder. Albumin in varying amounts is always present. Pus is nearly always present, though frequently not abundant. It is generally intimately mixed with the urine, and does not settle so quickly as the pus of cystitis. Casts, though present, are rarely abundant, and are obscured by the pus. Small amounts of blood are common. Tubercle bacilli are nearly always present, although animal inoculation may be necessary to detect them. 4. Renal Calculus.—The urine is usually somewhat concentrated, with high color and strongly acid reaction. Small amounts of albumin and a few casts may be present as a result of kidney irritation. Blood is frequently present, especially in the daytime and after severe exercise. Crystals of the substance composing the calculus—uric 5. Pyelitis.—In pyelitis the urine is slightly acid, and contains a small or moderate amount of pus, together with many spindle and caudate epithelial cells. Pus-casts may appear if the process extends up into the kidney tubules (see Fig. 62). Albumin is always present, and its amount, in proportion to the amount of pus, is decidedly greater than is found in cystitis.
6. Cystitis.—-In acute and subacute cases the urine is acid and contains a variable amount of pus, with many epithelial cells from the bladder—chiefly large round, pyriform, and rounded squamous cells. Red blood-corpuscles are often numerous. In chronic cases the urine is generally alkaline. It is
7. Vesical Calculus, Tumors, and Tuberculosis.—These conditions produce a chronic cystitis, with its characteristic urine. Blood, however, is more frequently present and more abundant than in ordinary cystitis. With neoplasms, especially, considerable hemorrhages are apt to occur. Particles of the tumor are sometimes passed with the urine. No diagnosis can be made from the presence of isolated tumor cells. In tuberculosis tubercle bacilli can generally be detected. 8. Diabetes Insipidus.—Characteristic of this disease is the continued excretion of very large quantities of pale, watery urine, containing neither albumin nor sugar. The 9. Diabetes Mellitus.—The quantity of urine is very large. The color is generally pale, while the specific gravity is nearly always high—1.030 to 1.050, very rarely below 1.020. The presence of glucose is the essential feature of the disease. The amount of glucose is often very great, sometimes exceeding 8 per cent., while the total elimination may exceed 500 gm. in twenty-four hours. It may be absent temporarily. Acetone is generally present in advanced cases. Diacetic acid may be present, and usually warrants an unfavorable prognosis. CHAPTER IIITHE BLOODPreliminary Considerations.—The blood consists of a fluid of complicated and variable composition, the plasma, in which are suspended great numbers of microscopic structures: viz., red corpuscles, white corpuscles, blood-platelets, and blood-dust. Red corpuscles, or erythrocytes, are biconcave discs, red when viewed by reflected light or in thick layer, and straw-colored when viewed by transmitted light or in thin layer. They give the blood its red color. They are cells which have been highly differentiated for the purpose of carrying oxygen from the lungs to the tissues. This is accomplished by means of an iron-bearing proteid, hemoglobin, which they contain. In the lungs hemoglobin forms a loose combination with oxygen, which it readily gives up when it reaches the tissues. Normal erythrocytes do not contain nuclei. They are formed from preËxisting nucleated cells in the bone-marrow. White corpuscles, or leukocytes, are less highly differentiated cells. There are several varieties. They all contain nuclei, and most of them contain granules which vary in size and staining properties. They are formed in the bone-marrow and lymphoid tissues. Blood-platelets, or blood-plaques, are colorless or slightly bluish, spheric or ovoid bodies, about one-third or one-half the diameter of an erythrocyte. Their structure, nature, and origin have not been definitely determined. Coagulation consists essentially in the transformation of fibrinogen, one of the proteins of the blood, into fibrin by means of a ferment derived from disintegration of the leukocytes. The resulting coagulum is made up of a meshwork of fibrin fibrils with entangled corpuscles and plaques. The clear, straw-colored fluid which is left after separation of the coagulum is called blood-serum. Normally, coagulation takes place in two to eight minutes after the blood leaves the vessels. It is frequently desirable to determine the coagulation time. The simplest method is to place a drop of blood upon a perfectly clean slide, and to draw a needle through it at half-minute intervals. When the clot is dragged along by the needle, coagulation has taken place. This method is probably sufficient for ordinary clinical work. For very accurate results the method of Russell and Brodie, for which the reader is referred to the larger text-books, is recommended. Coagulation is notably delayed in hemophilia and icterus and after administration of citric acid. It is hastened by administration of calcium chlorid. For most clinical examinations only one drop of blood is required. This may be obtained from the lobe of the ear, the palmar surface of the tip of the finger, or, in the case of infants, the plantar surface of the great toe. With nervous children the lobe of the ear is preferable, as it prevents their seeing what is being done. An edematous or congested part should be avoided. The site should be well rubbed with alcohol to remove dirt and epithelial
When a larger amount of blood is required, it may be obtained with a sterile hypodermic syringe from one of the veins at the elbow. Clinical study of the blood may be discussed under the following heads: I. Hemoglobin. II. Enumeration of erythrocytes. III. Color index. IV. Enumeration of leukocytes. V. Enumeration of plaques. VI. Study of stained blood. VII. Blood parasites. VIII. Serum reactions. IX. Tests for recognition of blood. X. Special blood pathology. I. HEMOGLOBIN Hemoglobin is an iron-bearing proteid. It is found only within the red corpuscles, and constitutes about 90 per cent. of their weight. The actual amount of hemoglobin is never estimated clinically: it is the relation which the amount present bears to the normal which is determined. Thus the expression, "50 per cent. hemoglobin," when used clinically, means that the blood contains 50 per cent. of the normal. Theoretically, the normal would be 100 per cent., but with the methods of estimation in general use the blood of healthy persons ranges from 85 to 105 per cent.; these figures may, therefore, be taken as normal. Increase of hemoglobin, or hyperchromemia, is uncommon, and is probably more apparent than real. It accompanies an increase in number of erythrocytes, and may be noted in change of residence from a lower to a higher altitude; in poorly compensated heart disease with cyanosis; in concentration of the blood from any cause, as the severe diarrhea of cholera; and in "idiopathic polycythemia." Decrease of hemoglobin, or oligochromemia, is very common and important. It is the most striking feature of the secondary anemias (p. 204). Here the hemoglobin loss may be slight or very great. In mild cases a slight decrease of hemoglobin is the only blood change noted. In very severe cases, especially in repeated hemorrhages, malignant disease, and infection by the worms uncinaria and bothriocephalus latus, hemoglobin may fall to 15 per cent. Hemoglobin is always diminished, and usually very greatly, in chlorosis, pernicious anemia, and leukemia.
Of the methods given, the physician should select the one which best meets his needs. With any method, practice is essential to accuracy. The von Fleischl has long been the standard instrument, but has lately fallen into some disfavor. For accurate work the best instruments are the von Fleischl-Miescher and the Dare. They are, however, expensive, and it is doubtful whether they are enough more accurate than the Sahli instrument to justify the difference in cost. The latter is probably the most satisfactory for the practitioner, provided a II. ENUMERATION OF ERYTHROCYTES In health there are about 5,000,000 red corpuscles per cubic millimeter of blood. Normal variations are slight. The number is generally a little less—about 4,500,000—in women. Increase of red corpuscles, or polycythemia, is unimportant. There is a decided increase following change of residence from a lower to a higher altitude, averaging about 50,000 corpuscles for each 1000 feet, but frequently much greater. The increase, however, is not permanent. In a few months the erythrocytes return to nearly their original number. Three views are offered in explanation: (a) Concentration of the blood, owing to increased evaporation from the skin; (b) stagnation of corpuscles in the peripheral vessels, because of lowered blood-pressure; (c) new-formation of corpuscles, this giving a compensatory increase of aËration surface. Pathologically, polycythemia is uncommon. It may occur in: (a) concentration of the blood from severe watery diarrhea; (b) chronic heart disease, especially the congenital variety, with poor compensation and cyanosis; and (c) idiopathic polycythemia, which is considered to be an independent disease, and is characterized by cyanosis, blood counts of 7,000,000 to 10,000,000, hemoglobin 120 to 150 per cent., and a normal number of leukocytes. Oligocythemia occurs in all but the mildest symptomatic anemias. The blood count varies from near the normal in moderate cases down to 1,500,000 in very severe cases. There is always a decrease of red cells in chlorosis, but it is often slight, and is relatively less than the decrease of hemoglobin. Leukemia gives a decided oligocythemia, the average count being about 3,000,000. The greatest loss of red cells occurs in pernicious anemia, where counts below 1,000,000 are not uncommon.
The most widely used and most satisfactory instrument for counting the corpuscles is that of Thoma-Zeiss. The hematocrit is not to be recommended for accuracy, since in anemia, where blood counts are most important, the red cells vary greatly in size and probably also in elasticity.
III. COLOR INDEX This is an expression which indicates the amount of hemoglobin in each red corpuscle compared with the normal amount. For example, a color index of 1.0 indicates that each corpuscle contains the normal amount The color index is most significant in chlorosis and pernicious anemia. In the former it is usually much decreased; in the latter, generally much increased. In symptomatic anemia it is generally moderately diminished.
IV. ENUMERATION OF LEUKOCYTES The normal number of leukocytes varies from 5000 to 10,000 per cubic millimeter of blood. The number is larger in robust individuals than in poorly nourished ones, and if disease be excluded, may be taken as an index of the individual's nutrition. Since it is well to have a definite standard, 7500 is generally adopted as the normal for the adult. With children the number is somewhat greater, counts of 12,000 and 15,000 being common in healthy children under twelve years of age. Decrease in number of leukocytes, or leukopenia, is not important. It is common in persons who are poorly nourished, although not actually sick. The infectious diseases in which leukocytosis is absent (p. 160) often cause a slight decrease of leukocytes. Chlorosis may Increase in number of leukocytes is common and of great importance. It may be considered under two heads: A. Increase of leukocytes due to chemotaxis and stimulation of the blood-making organs, or leukocytosis. B. Increase of leukocytes due to leukemia. The former may be classed as a transient, the latter, as a permanent, increase. This term has not acquired a definite meaning. By some it is applied to any increase in number of leukocytes; by others, it is restricted to increase of the polymorphonuclear neutrophilic variety. As has been indicated, it is here taken to mean any increase in number of leukocytes caused by chemotaxis and stimulation of the blood-producing structures; and includes every increase of leukocytes except that due to leukemia. By chemotaxis is meant that property of certain agents by which they attract or repel leukocytes—positive chemotaxis and negative chemotaxis respectively. An excellent illustration is the accumulation of leukocytes at the site of inflammation, owing to the positively chemotactic influence of bacteria and their products. A great many agents possess the power of attracting leukocytes into the general circulation. Among these are bacteria and many organic and inorganic poisons. Chemotaxis alone will not explain the continuance of leukocytosis for more than a short time. It is probable that substances which are positively chemotactic also stimulate the blood-producing organs to increased In general, the response of the leukocytes to chemotaxis is a conservative process. It is the gathering of soldiers to destroy an invader. This is accomplished partly by means of phagocytosis—actual ingestion of the enemy—and partly by means of chemic substances which the leukocytes produce. In those diseases in which leukocytosis is the rule the degree of leukocytosis depends upon two factors: the severity of the infection and the resistance of the individual. A well-marked leukocytosis usually indicates good resistance. A mild degree means that the body is not reacting well, or else that the infection is too slight to call forth much resistance. Leukocytosis may be absent altogether when the infection is extremely mild, or when it is so severe as to overwhelm the organism before it can react. These facts are especially true of pneumonia, diphtheria, and abdominal inflammations, in which conditions the degree of leukocytosis is of considerable prognostic value. As will be seen later, there are several varieties of leukocytes in normal blood, and many chemotactic agents attract only one variety and either repel or do not influence the others. These varieties may be divided into two general classes: (a) Those having active independent ameboid motion. They are able to migrate readily from place to place and to ingest small bodies, as bacteria. From this latter property they derive their name of phagocytes. This group includes all varieties except the lymphocytes. The polymorphonuclear leukocytes are taken as the type of the group, because they are by far the most numerous. By this classification we may distinguish two types of leukocytosis, according to the type of cell chiefly affected: a phagocytic and a non-phagocytic type. 1. Phagocytic Leukocytosis.—Theoretically, there should be a subdivision of phagocytic leukocytosis for each variety of phagocyte, e.g., polymorphonuclear leukocytosis, eosinophilic leukocytosis, large mononuclear leukocytosis, etc. Practically, however, only one of these, polymorphonuclear leukocytosis, need be considered under the head of leukocytosis. Increase in number of the other phagocytes will be considered at another place. They are present in the blood in such small numbers normally that even a marked increase scarcely affects the total leukocyte count; and, besides, substances which attract them into the circulation frequently repel the polymorphonuclears, so that the total number of leukocytes may actually be decreased. Polymorphonuclear leukocytosis may be either physiologic or pathologic. A count of 20,000 would be considered a marked leukocytosis; of 30,000, high; above 50,000, extremely high. (1) Physiologic Polymorphonuclear Leukocytosis.—This is never very marked, the count rarely exceeding 15,000 per cubic millimeter. It occurs in the new-born, in pregnancy, during digestion, and after cold baths. There is moderate leukocytosis in the moribund state; this is commonly classed as physiologic, but is probably due mainly to terminal infection. (a) Infectious and Inflammatory.—The majority of infectious diseases produce leukocytosis. The most notable exceptions are influenza, malaria, measles, tuberculosis, except when invading the serous cavities or when complicated by mixed infection, and typhoid fever, in which leukocytosis indicates an inflammatory complication. All inflammatory and suppurative diseases cause leukocytosis, except when slight or well walled off. Appendicitis has been studied with especial care in this connection, and the conclusions now generally accepted probably hold good for most acute intra-abdominal inflammations. A marked leukocytosis (20,000 or more) nearly always indicates abscess, peritonitis, or gangrene, even though the clinical signs be slight. Absence of or mild leukocytosis indicates a mild process, or else an overwhelmingly severe one; and operation may safely be postponed unless the abdominal signs are very marked. On the other hand, no matter how low the count, an increasing leukocytosis—counts being made hourly—indicates a spreading process and demands operation, regardless of other symptoms. Leukocyte counts alone are often disappointing, but are of much more value when considered in connection with a differential count of polymorphonuclears (see p. 181). (b) Malignant Disease.—Leukocytosis occurs in about one-half of the cases of malignant disease. In many instances it is probably independent of any secondary infection, since it occurs in both ulcerative and non-ulcerative cases. It seems to be more common in sarcoma than in carcinoma. Very large counts are rarely noted. (d) Toxic.—This is a rather obscure class, which includes gout, chronic nephritis, acute yellow atrophy of the liver, ptomain poisoning, prolonged chloroform narcosis, and quinin poisoning. Leukocytosis may or may not occur in these conditions, and is not important. (e) Drugs.—This also is an unimportant class. Most tonics and stomachics and many other drugs produce a slight leukocytosis. 2. Non-phagocytic or Lymphocyte Leukocytosis.—This is characterized by an increase in the total leukocyte count, accompanied by an increase in the percentage of lymphocytes. The word "lymphocytosis" is often used in the same sense. It is better, however, to use the latter as referring to any increase in number of lymphocytes, without regard to the total count, since an actual increase in number of lymphocytes is frequently accompanied by a normal or subnormal leukocyte count, owing to loss of polymorphonuclears. Non-phagocytic leukocytosis is probably due more to stimulation of blood-making organs than to chemotaxis. It is less common, and is rarely so marked as a polymorphonuclear leukocytosis. When marked, the blood cannot be distinguished from that of lymphatic leukemia. A marked lymphocyte leukocytosis occurs in pertussis, and is of value in diagnosis. It appears early in the catarrhal stage, and persists until after convalescence. The average leukocyte count is about 17,000, lymphocytes predominating. There is moderate lymphocyte leukocytosis in other diseases of childhood, as rickets, scurvy, and especially hereditary syphilis, where the blood-picture Slight lymphocyte leukocytosis occurs in many other pathologic conditions, but is of little significance. B. LEUKEMIA This is an idiopathic disease of the blood-making organs, which is accompanied by an enormous increase in number of leukocytes. The leukocyte count sometimes exceeds 1,000,000 per cubic millimeter, and leukemia is always to be suspected when it exceeds 50,000. Lower counts do not, however, exclude it. The subject is more fully discussed later (p. 208). The leukocytes are counted with the Thoma-Zeiss instrument, already described. Recently, several new rulings of the disc have been introduced, notably the Zappert and the TÜrk (Fig. 72), which give a ruled area of nine square millimeters. They were devised for counting the leukocytes in the same specimen with the red corpuscles. The red cells are counted in the usual manner, after which all the leukocytes in the whole area of nine square millimeters are counted; and the number in a cubic millimeter of undiluted blood is then easily calculated. Leukocytes are easily distinguished from red cells, especially when Toisson's diluting fluid is used. This method may be used with the ordinary ruling by adjusting the microscopic field to a definite size, and counting a sufficient number of fields, as described later. Although less convenient, it is more accurate to count the leukocytes separately, with less dilution of the blood, as follows:
V. ENUMERATION OF BLOOD-PLAQUES The average normal number of plaques is variously given as 200,000 to 700,000 per c.mm. of blood. The latter figure probably more nearly represents the true normal average, since the lower counts were obtained for the most part by workers who used unreliable methods. Physiologic variations are marked; thus, the number Pathologic variations are often very great. Owing to lack of knowledge as to the origin of the platelets and to the earlier imperfect methods of counting, the clinical significance of these variations is uncertain. The following facts seem, however, to be established: (a) In acute infectious diseases the number is subnormal or normal. If the fever ends by crisis, the crisis is accompanied by a rapid and striking increase. (b) In secondary anemia plaques are generally increased, although sometimes decreased. In pernicious anemia they are always greatly diminished, and an increase should exclude the diagnosis of this disease. (c) They are decreased in chronic lymphatic leukemia, and greatly increased in the myelogenous form. (d) In purpura hÆmorrhagica the number is enormously diminished. Blood-plaques are difficult to count owing to the rapidity with which they disintegrate and to their great tendency to adhere to any foreign body and to each other. The method of Kemp, Calhoun, and Harris is practical and is to be recommended:
r:p :: R:P; and P = p x R/r.
VI. STUDY OF STAINED BLOOD A. MAKING AND STAINING BLOOD-FILMS 1. Spreading the Film.—Thin, even films are essential to accurate and pleasant work. They more than compensate for the time spent in learning to make them. There are certain requisites for success with any method: (a) The slides and covers must be perfectly clean; thorough washing with soap and water and rubbing with alcohol will usually suffice; (b) the drop of blood must not be too large; (c) the work must be done quickly, before coagulation begins. The blood is obtained from the finger-tip or the lobe of the ear, as for a blood count; only a very small drop is required.
The films may be allowed to dry in the air, or may be dried by gently heating high above a flame (where one can comfortably hold the hand). Such films will keep for years, but for some stains they must not be more than a few weeks old. They must be kept away from flies—a fly can work havoc with a film in a few minutes. 2. Fixing the Film.—In general, films must be "fixed" before they are stained. Fixation may be accomplished by chemicals or by heat. Those stains which are dissolved in methyl-alcohol combine fixation with the staining process.
3. Staining the Film.—The anilin dyes, which are extensively used in blood work, are of two general classes: (1) Eosin and Methylene-blue.—In many instances this stain will give all the information desired. It is especially useful in studying the red corpuscles. Nuclei, basophilic granules, and all blood parasites are blue; erythrocytes are red or pink; eosinophilic granules, bright red. Neutrophilic granules and blood-plaques are not stained.
(2) Ehrlich's Triple Stain.—This has been the standard blood-stain for many years, and is still widely used. It is probably the best for neutrophilic granules. It is difficult to make, and should be purchased ready prepared from a reliable dealer. Nuclei are stained blue or greenish-blue; erythrocytes, orange; neutrophilic granules, violet; and eosinophilic granules, copper red. Success in staining depends largely upon proper fixation. The film must be carefully fixed by heat: underheating causes the erythrocytes to stain red; overheating, pale yellow. The staining fluid is applied for five to fifteen minutes, and the preparation is rinsed quickly in water, dried, and mounted. Subsequent application of LÖffler's methylene-blue for one-half to one second will bring out the basophilic granules, and improve the nuclear staining, but there is considerable danger of overstaining. (3) Wright's Stain.—Recently the polychrome methylene-blue-eosin stains, dissolved in methyl-alcohol, have largely displaced other blood-stains for clinical purposes. They combine the fixing with the staining process, and stain differentially every normal and abnormal structure in the blood. Numerous methods of preparing and applying these stains have been devised. Wright's stain is one of the best, and is the most widely used in this country. Directions for preparing it are given in most of the newer large text-books upon clinical diagnosis. The practitioner will find it best to purchase the stain ready prepared. Most microscopic supply houses keep it in stock. The method of application is as follows:
When properly applied, Wright's stain gives the following picture (Plate VI): erythrocytes, yellow or pink; nuclei, various shades of bluish-purple; neutrophilic granules, reddish-lilac; eosinophilic granules, bright red; basophilic granules of leukocytes and degenerated red corpuscles, very dark bluish-purple; blood-plaques, dark lilac; bacteria, blue. The cytoplasm of lymphocytes is generally robin's-egg blue; that of the large mononuclears may have a faint bluish tinge. Malarial parasites stain characteristically: the cytoplasm, sky-blue; the chromatin, reddish-purple. Jenner's stain, which gives a somewhat similar picture, is preferred by many for differential counting of leukocytes. It brings out neutrophilic granules rather more clearly, but does not compare with Wright's fluid as a stain for the malarial parasite. Unfixed films are stained about three minutes, rinsed quickly, dried, and mounted. For the physician who wishes to use only one blood-stain, Wright's fluid is undoubtedly the best of those mentioned.
B. STUDY OF STAINED FILMS Much can be learned from stained blood-films. They furnish the best means of studying the morphology of the blood and blood parasites, and, to the experienced, they give a fair idea of the amount of hemoglobin and the number of red and white corpuscles. A one-twelfth-inch objective is required. 1. Erythrocytes.—Normally, the red corpuscles are acidophilic. The colors which they take with different stains have been described. When not crowded together, they appear as circular, homogeneous discs, of nearly uniform size, averaging 7.5 µ in diameter (Fig. 84). The center of each is somewhat paler than the periphery. The degree of pallor furnishes a rough index to the amount of hemoglobin in the corpuscle. They are apt to be crenated when the film has dried too slowly. Pathologically, red corpuscles vary in size and shape, staining properties, and structure. (1) Variations in Size and Shape (See Plate VIII and Fig. 84).—The cells may be abnormally small (called microcytes, 5 µ or less in diameter); abnormally large (macrocytes, 10 to 12 µ); or extremely large (megalocytes, 12 to 20 µ). Variation in shape is often very marked. Oval, pyriform, caudate, saddle-shaped, and club-shaped corpuscles are common. They are called poikilocytes, and their presence is spoken of as poikilocytosis. Red corpuscles which vary from the normal in size and shape are present in most symptomatic anemias, and in the severer grades are often very numerous. Irregularities are particularly conspicuous in leukemia and pernicious anemia, where, in some instances, a normal erythrocyte (2) Variations in Staining Properties (See Plate VIII).—These include polychromatophilia, basophilic degeneration, and basophilic stippling. They are probably degenerative changes, although polychromatophilia is thought by many to be evidence of youth in a cell, and hence to indicate an attempt at blood regeneration. (a) Polychromatophilia.—Some of the corpuscles partially lose their normal affinity for acid stains, and take the basic stain to greater or less degree. Wright's stain gives such cells a faint bluish tinge when the condition is mild, and a rather deep blue when severe. Sometimes only part of a cell is affected. A few polychromatophilic corpuscles can be found in marked symptomatic anemias. They occur most abundantly in malaria, leukemia, and pernicious anemia. (b) Basophilic Granular Degeneration (Degeneration of Grawitz).—This is characterized by the presence, within the corpuscle, of small basophilic granules. They stain deep blue with Wright's stain; not at all, with Ehrlich's triple stain. The cell containing them may stain normally in other respects, or it may exhibit polychromatophilia. Numerous cells showing this degeneration are commonly found in chronic lead-poisoning, of which they were at one time thought to be pathognomonic. Except in this disease, the degeneration indicates a serious blood condition. It occurs in well-marked cases of pernicious anemia and leukemia, and, much less commonly, in very severe symptomatic anemias. (c) Basophilic Stippling.—This term has been applied (3) Variations in Structure.—The most important is the presence of a nucleus (Plates VI and VIII and Fig. 84). Nucleated red corpuscles, or erythroblasts, are classed according to their size: microblasts, 5 µ or less in diameter; normoblasts, 5 to 10 µ; and megaloblasts, above 10 µ. Microblasts and normoblasts contain one, rarely two, small, round, sharply defined, deeply staining nuclei, often located eccentrically. Occasionally the nucleus is irregular in shape, "clover-leaf" forms being not infrequent. The megaloblast is probably a distinct cell, not merely a larger size of the normoblast. Its nucleus is large, stains rather palely, has a delicate chromatin network, and often shows evidences of degeneration (karyorrhexis, etc.). In ordinary work, however, it is safer to base the distinction upon size than upon structure. Any nucleated red cell, but especially the megaloblast, may exhibit polychromatophilia. Normally, erythroblasts are present only in the blood of the fetus and of very young infants. Pathologically, normoblasts occur in severe symptomatic anemia, leukemia, and pernicious anemia. They are most abundant in myelogenous leukemia. While always present in pernicious anemia, they are often difficult to find. Megaloblasts are found in pernicious anemia, and with extreme rarity in any other condition. They almost invariably 2. The Leukocytes.—An estimation of the number or percentage of each variety of leukocyte in the blood is called a differential count. The differential count is best made upon a film stained with Wright's, Jenner's, or Ehrlich's stain. Go carefully over the film with an oil-immersion lens, using a mechanical stage if available. Classify each leukocyte seen, and calculate what percentage each variety is of the whole number classified. For accuracy, 500 to 1000 leukocytes must be classified; for approximate results, 200 are sufficient. Track of the count may be kept by placing a mark for each leukocyte in its appropriate column, ruled upon paper. Some workers divide a slide-box into compartments with slides, one for each variety of leukocyte, and drop a coffee-bean into the appropriate compartment when a cell is classified. When a convenient number of coffee-beans is used (any multiple of 100), the percentage calculation is extremely easy. The actual number of each variety in a cubic millimeter of blood is easily calculated from these percentages and the total leukocyte count. An increase in actual number is an absolute increase; an increase in percentage only, a relative increase. It is evident that an absolute increase of any variety may be accompanied by a relative decrease. A record is generally kept of the number of nucleated red cells seen during a differential count of leukocytes. The usual classification of leukocytes is based upon their size, their nuclei, and the staining properties of the granules (1) Normal Varieties.—(a) Lymphocytes.—These are small mononuclear cells without granules (Plate VI and Fig. 86). They are about the size of a red corpuscle or slightly larger, and consist of a single, sharply defined, deeply staining nucleus, surrounded by a narrow rim of protoplasm. The nucleus is generally round, but is sometimes indented at one side. Wright's stain gives the nucleus a deep purple color and the cytoplasm a pale robin's-egg blue in typical cells. Larger forms of lymphocytes are frequently found, especially in the blood of children, and are difficult to distinguish from the large mononuclear leukocytes. Lymphocytes are formed in the lymphoid tissues, including that of the bone-marrow. They constitute, normally, 20 to 30 per cent. of all leukocytes, or about 1000 to 3000 per c.mm. of blood. They are more abundant in the blood of children. The percentage of lymphocytes is usually moderately increased in those conditions which give leukopenia, especially typhoid fever, chlorosis, pernicious anemia, and many debilitated conditions. A marked increase, accompanied by an increase in the total leukocyte count, is seen in pertussis and lymphatic leukemia. In the latter, the lymphocytes sometimes exceed 98 per cent. (b) Large Mononuclear Leukocytes (Plate VI).—These cells are two or three times the diameter of the normal red corpuscle. Each contains a single round or oval nucleus, often located eccentrically. The zone of protoplasm surrounding the nucleus is relatively wide. With Large mononuclear leukocytes probably originate in the bone-marrow or spleen. They constitute 2 to 4 per cent. of the total number of leukocytes: 100 to 400 per c.mm. of blood. An increase is unusual except in malaria, where it is quite constantly observed, and where many of the cells contain ingulfed pigment. (c) Transitional Leukocytes (Plate VI).—These are essentially large mononuclears with deeply indented or horseshoe-shaped nuclei. A few fine neutrophilic granules are sometimes present in their cytoplasm. They are probably formed from the large mononuclears, and occur in the blood in about the same numbers. The two cells are usually counted together. (d) Polymorphonuclear Neutrophilic Leukocytes (Plate VI).—There is usually no difficulty in recognizing these cells. Their average size is somewhat less than that of the large mononuclears. The nucleus stains rather deeply, and is extremely irregular, often assuming shapes comparable to letters of the alphabet, E, Z, S, etc. (Fig. 86). Frequently there appear to be several separate nuclei, hence the widely used name, "polynuclear Polymorphonuclear leukocytes are formed in the bone-marrow from neutrophilic myelocytes. They constitute 60 to 75 per cent. of all the leukocytes: 3000 to 7500 per c.mm. of blood. Increase in their number practically always produces an increase in the total leukocyte count, and has already been discussed under "phagocytic leukocytosis." The leukocytes of pus, pus-corpuscles, belong almost wholly to this variety. A comparison of the percentage of polymorphonuclear cells with the total leukocyte count yields more information than a consideration of either alone. With moderate infection and good resisting powers the leukocyte count and the percentage of polymorphonuclears are increased proportionately. When the polymorphonuclear percentage is increased to a notably greater extent than is the total number of leukocytes, no matter how low the count, either very poor resistance or a very severe infection may be inferred. In the absence of acute infectious disease a polymorphonuclear percentage of 85 or over points very strongly to gangrene or pus-formation. On the other hand, except in children, where the percentage is normally low, pus is uncommon with less than 80 per cent. of polymorphonuclears. Normally, the cytoplasm of leukocytes stains pale yellow with iodin. Under certain pathologic conditions the cytoplasm of many of the polymorphonuclears stains This iodin reaction occurs in all purulent conditions except abscesses which are thoroughly walled off or purely tuberculous abscesses. It is of some value in diagnosis between serous effusions and purulent exudates, between catarrhal and suppurative processes in the appendix and Fallopian tube, etc. Its importance, however, as a diagnostic sign of suppuration has been much exaggerated, since it may occur in any general toxemia, such as pneumonia, influenza, malignant disease, and puerperal sepsis. To demonstrate iodophilia, place the air-dried films in a stoppered bottle containing a few crystals of iodin until they become yellow. Mount in syrup of levulose and examine with a one-twelfth objective. (e) Eosinophilic Leukocytes, or "Eosinophiles" (Plate VI).—The structure of these cells is similar to that of the polymorphonuclear neutrophiles, with the striking difference that, instead of fine neutrophilic granules, their cytoplasm contains coarse granules having a strong affinity for acid stains. They are easily recognized by the size and color of the granules, which stain bright red with Wright's stain. Eosinophiles are formed in the bone-marrow from eosinophilic myelocytes. Their normal number varies from 50 to 400 per c.mm. of blood, or 1 to 4 per cent. of the leukocytes. An increase is called eosinophilia, and is better determined by the actual number than by the percentage. Slight eosinophilia is physiologic during menstruation. Eosinophilia may be a symptom of infection by any of the worms. It is fairly constant in trichinosis, uncinariasis, filariasis, and echinococcus disease. In this country an unexplained marked eosinophilia warrants examination of a portion of muscle for Trichina spiralis (p. 255). True bronchial asthma commonly gives a marked eosinophilia during and following the paroxysms. This is helpful in excluding asthma of other origin. Eosinophiles also appear in the sputum in large numbers. In myelogenous leukemia there is almost invariably an absolute increase of eosinophiles, although, owing to the great increase of other leukocytes, the percentage is usually diminished. Dwarf and giant forms are often numerous. Scarlet fever is frequently accompanied by eosinophilia, which may help to distinguish it from measles. Eosinophilia has been observed in a large number of skin diseases, notably pemphigus, prurigo, psoriasis, and urticaria. It probably depends less upon the variety of the disease than upon its extent. (f) Basophilic Leukocytes or "Mast-cells" (Plate VI).—In general, these resemble polymorphonuclear neutrophiles except that the nucleus is less irregular and that the granules are larger and have a strong affinity for basic stains. They are easily recognized. With Wright's stain the granules are deep purple, while the nucleus is pale blue and is nearly or quite hidden by the granules, so that its form is difficult to make out. These granules are not colored by Ehrlich's stain. (2) Abnormal Varieties.—(a) Myelocytes (Plate VI).—These are large mononuclear cells whose cytoplasm is filled with granules. Typically, the nucleus occupies about one-half of the cell, and is round or oval. It is sometimes indented, with its convex side in contact with the periphery of the cell. It stains rather feebly. The average diameter of this cell (about 15.75 µ) is greater than that of any other leukocyte, but there is much variation in size among individual cells. Myelocytes are named according to the character of their granules—neutrophilic, eosinophilic, and basophilic myelocytes. These granules are identical with the corresponding granules in the leukocytes just described. The occurrence of two kinds of granules in the same cell is rare. Myelocytes are the bone-marrow cells from which the corresponding granular leukocytes are developed. Their presence in the blood in considerable numbers is diagnostic of myelogenous leukemia. The neutrophilic form is the less significant. A few of these may be present in very marked leukocytosis or any severe blood condition, as pernicious anemia. Eosinophilic myelocytes are found only in myelogenous leukemia, where they are often very numerous. The basophilic variety is less common, and is confined to long-standing severe myelogenous leukemia. (b) Atypical Forms.—Leukocytes which do not fit in 3. Blood-plaques.—These are not colored by Ehrlich's stain, nor by eosin and methylene-blue. With Wright's stain they appear as spheric or ovoid, reddish to violet, granular bodies, 2 to 4 µ in diameter. When well stained, a delicate hyaline peripheral zone can be distinguished. In ordinary blood-smears they are usually clumped in masses. A single platelet lying upon a red corpuscle may easily be mistaken for a malarial parasite (Plate VI). Blood-platelets are being much studied at present, but, aside from the facts mentioned under their enumeration (p. 165), little of clinical value has been learned. They have been variously regarded as very young red corpuscles (the "hematoblasts" of Hayem), as disintegration products of leukocytes, as remnants of extruded nuclei of erythrocytes, and as independent nucleated bodies. The most probable explanation of their origin seems to be that of A study of blood bacteriology is useful, but is hardly practicable for the practitioner. Most bacteria can be detected only by culture methods. The spirillum of relapsing fever can be identified by the method for the malarial parasite in fresh blood. The blood must be taken during a paroxysm. The organism is an actively motile spiral thread, about four times the diameter of a red corpuscle in length. The movements which its active motion causes among the corpuscles render it conspicuous. It can also be seen in stained preparations (Fig. 78). The disease has rarely been seen in the United States.
Of the numerous animal parasites which have been 1. Plasmodium MalariÆ.—This organism is one of a large group, the hemosporidia (p. 247), many of which live within and destroy the red corpuscles of various animals. Three varieties are associated with malarial fever in man—the tertian, quartan, and estivo-autumnal malarial parasites. (1) Life Histories.—There are two cycles of development: one, the asexual, in the blood of man; and the other, the sexual, in the intestinal tract of a particular variety of mosquito. (a) Asexual Cycle.—The young organism enters the blood through the bite of the mosquito. It makes its way into a red corpuscle, where it appears as a small, pale "hyaline" body. This body exhibits ameboid movement and increases in size. Soon, dark-brown granules derived from the hemoglobin of the corpuscle make their appearance within it. When it has reached its full size—filling and distending the corpuscle in the case of the tertian parasite, smaller in the others—the pigment-granules gather at the center or at one side; the organism divides into a number of small hyaline bodies, the spores or merozoites; and the red corpuscle bursts, setting spores and pigment free in the blood-plasma. This is called segmentation. It coincides with, and by liberation of toxins causes, the paroxysm of the disease. A considerable number of the spores are destroyed by leukocytes or other agencies; the remainder enter other corpuscles and repeat the cycle. Many of the pigment-granules are taken up by leukocytes. In estivo-autumnal fever segmentation occurs in the The asexual cycle of the tertian organism occupies forty-eight hours; of the quartan, seventy-two hours; of the estivo-autumnal, an indefinite time—usually twenty-four to forty-eight hours. The parasites are thus present in the blood in great groups, all the individuals of which reach maturity and segment at approximately the same time. This explains the regular recurrence of the paroxysms at intervals corresponding to the time occupied by the asexual cycle of the parasite. Not infrequently there is multiple infection, one group reaching maturity while the others are still young; but the presence of two groups which segment upon the same day is extremely rare. Fevers of longer intervals—six, eight, ten days—are probably due to the ability of the body, sometimes of itself, sometimes by aid of quinin, to resist the parasites so that a number sufficient to cause a paroxysm do not accumulate in the blood until after several repetitions of the asexual cycle. In estivo-autumnal fever the regular grouping, while usually present at first, is soon lost, thus causing "irregular malaria." (b) Sexual Cycle.—Besides the ameboid individuals which pass through the asexual cycle, there are present with them in the blood many individuals with sexual properties. These are called gametes. They do not undergo segmentation. Many of them are apparently extracellular, but stained preparations usually show them to be surrounded by the remains of a corpuscle. In tertian and quartan malaria they cannot easily be distinguished from the asexual individuals until a variable time after the blood leaves the body, when the male gamete sends out When a malarious person is bitten by a mosquito, the gametes are taken with the blood into its stomach. Here a flagellum from the male unites with the female, which soon thereafter becomes encysted in the wall of the intestine. After a time it ruptures, liberating many minute rods, or sporozoites, which have formed within it. These migrate to the salivary glands, and are carried into the blood of the person whom the mosquito bites. Here they enter red corpuscles as young malarial parasites, and the majority pass through the asexual cycle just described.
The sexual cycle can take place only within the body of one genus of mosquito, anopheles. Absence of this mosquito from certain districts explains the absence of (2) Detection.—Search for the malarial parasite may be made in either fresh blood or stained films. If possible, the blood should be obtained a few hours before the chill—never during it nor within a few hours afterward, since at that time (in single infections) only the very young, unpigmented forms are present, and these are the most difficult to find and recognize. Sometimes many parasites are found in a microscopic field; sometimes, especially in estivo-autumnal infection, owing to accumulation in internal organs, careful search is required to find any, despite very severe symptoms. Quinin causes them rapidly to disappear from the peripheral blood, and few or none may be found after its administration. In the absence of organisms, the presence of pigment granules within leukocytes—polymorphonuclears and large mononuclears—may be taken as presumptive evidence of malaria. Pigmented leukocytes (Plate VI) are most numerous after a paroxysm. (a) In Fresh Unstained Blood (Plate VII).—Obtain a small drop of blood from the finger or lobe of the ear. Touch the center of a cover-glass to the top of the drop and quickly place it, blood side down, upon a slide. If the slide and cover be perfectly clean and the drop not too large, the blood will spread out so as to present only one layer of corpuscles. Search with a one-twelfth-inch objective, using very subdued light.
(b) In Stained Films (Plate VI).—Recognition of the parasite, especially the young forms, is much easier in films stained by Wright's or some similar stain than in fresh blood. When very scarce, they may sometimes be found, although their structure is not well shown, by the method of Ruge. This consists in spreading a very thick layer of blood, drying, placing for a few minutes in a fluid containing 5 per cent. formalin and 1 per cent. acetic acid, which removes the hemoglobin and fixes the smear, rinsing, drying, and finally staining. If Wright's stain be used in this method, it is recommended that the In films which are properly stained with Wright's fluid the young organisms are small, round, ring-like or irregular, sky-blue bodies, each with a very small, sharply defined, reddish-purple chromatin mass. Many structures—deposits of stain, dirt, blood-plaques lying upon red cells, etc.—may simulate them, but should not deceive one who looks carefully for both the blue cytoplasm and the reddish-purple chromatin. A plaque upon a red corpuscle is surrounded by a colorless zone rather than by a distinct blue body. Young estivo-autumnal parasites commonly take a "ring" form (the chromatin mass representing the jewel), which is infrequently assumed by the other varieties. The older tertian and quartan organisms show larger sky-blue bodies with more reticular chromatin, and contain brown granules of pigment, which, however, is less evident than in the living parasite. The chromatin is often scattered through the cytoplasm or apparently outside of it, and is sometimes difficult to see clearly. Typical "segmenters" present a ring of rounded segments or spores, each with a small, dot-like chromatin mass. With the tertian parasite, the segments more frequently form an irregular cluster. The pigment is collected near the center or scattered among the segments. In estivo-autumnal fever usually only the small "ring bodies" and the crescentic and ovoid gametes are seen in the blood. The gametes are easily recognized. Their length is somewhat greater than the diameter of a red corpuscle. Their chromatin is usually centrally placed, and they contain more or less coarse pigment. The remains of the While the parasites are more easily found in stained preparations, the varieties are more easily differentiated in fresh blood. The chief distinguishing points are included in the following table:
2. Filaria Sanguinis Hominis.—Of the several varieties of this worm, Filaria nocturna is most common and The female is viviparous, and produces vast numbers of embryos, which appear in the circulating blood. These embryos are very actively motile, worm-like structures, about as wide as a red corpuscle and 0.2 to 0.4 mm. long (Fig. 107). They are found in the peripheral blood only at night, appearing about 8 P.M. and reaching their maximum number—which is sometimes enormous—about midnight. If the patient change his time of sleeping, they will appear during the day. Infection is carried by a variety of mosquito, which acts as intermediate host. Diagnosis rests upon detection of embryos in the blood. They can be seen in stained preparations, but are best found in fresh unstained blood. A rather large drop is taken upon a slide, covered, and examined with a low power. The embryo can be located by the commotion which its active motion produces among the corpuscles. This motion consists almost wholly in apparently purposeless lashing and coiling movements, and continues for many hours. 3. Trypanosoma Hominis.—Various trypanosomes are common in the blood of fishes, amphibians, birds, and
Trypanosoma hominis is an actively motile, spindle-shaped organism, two or three times the diameter of a red corpuscle in length, with one end terminating in a long flagellum. It can be seen with medium power objectives in either fresh or stained blood. Human trypanosomiasis is common in Africa. As a rule, it is a very chronic disease. "Sleeping sickness" is a late stage when the organisms have invaded the cerebrospinal fluid. Infection is carried by a biting fly, Glossina palpalis. VIII. SERUM REACTIONS 1. Agglutination.—In the blood-serum of persons suffering from certain infectious diseases there exist soluble bodies, called agglutinins, which have the property of When applied to the diagnosis of typhoid fever, the phenomenon is known as the Widal reaction. As yet, it is the only agglutination reaction which has any practical value for the practitioner. Either blood-serum or the whole blood may be used. Serum is the better. To obtain it, it is convenient to use little vials, such as can be made by breaking off the lower half-inch of the tubes which have contained peptonizing powder. They must, of course, be well cleaned. One of these is filled to a depth of about one-fourth inch from a puncture in the finger, and is set aside for a few hours. When the clot has separated, it is picked out with a needle, leaving the serum. One drop of the serum is then added to nine drops of normal salt solution, making a dilution of 1:10. Distilled water may be used for dilution, but is more liable to cause error. The dilution can be more accurately made in the leukocyte pipet of the Thoma-Zeiss instrument. When the whole blood is used, it can be secured in the pipet and at once diluted with the salt solution. When it must be transported a considerable distance, dried blood is most convenient. A large drop is allowed to dry upon a clean slide or unglazed paper. It will keep for months without losing its agglutinating power. When ready to make the test, the dried stain is dissolved in ten drops of normal salt solution, care being The reaction can be detected either microscopically or macroscopically:
2. Opsonins.—That phagocytosis plays an important part in the body's resistance to bacterial invasion has long been recognized. According to Metchnikoff, this property of leukocytes resides entirely within themselves, depending upon their own vital activity. The recent studies of Wright and Douglas, upon the contrary, indicate that the leukocytes are impotent in themselves, and can ingest bacteria only in the presence of certain substances which exist in the blood-plasma. These substances have been named opsonins. Their nature is undetermined. They probably act by uniting with the bacteria, thus preparing them for ingestion by the leukocytes; but they do not cause death of the bacteria, nor produce any appreciable morphologic change. They appear to be more or less specific, a separate opsonin being necessary for phagocytosis of each species of bacteria. There are, moreover, opsonins for other formed elements—red blood-corpuscles, for example. It has been shown that the quantity of opsonins in the blood can be greatly increased by inoculation with dead bacteria. To measure the amount of any particular opsonin in the blood Wright has devised a method which involves many ingenious and delicate technical procedures. Much skill, such as is attained only after considerable training in laboratory technic, is requisite, and there are many sources Wright and his followers regard the opsonic index as an index of the power of the body to combat bacterial invasion. They claim very great practical importance for it as an aid to diagnosis and as a guide to treatment by the vaccine method. This method of treatment consists in increasing the amount of protective substances in the blood by injections of normal-salt suspensions of dead bacteria of the same species as that which has caused and is maintaining the morbid process, these bacterial suspensions being called "vaccines." The opinion of the majority of conservative men seems to be that while vaccine therapy is undoubtedly an important addition to our IX. TESTS FOR RECOGNITION OF BLOOD 1. Guaiac Test.—The technic of this test has been given (p. 89). It may be applied directly to a suspected fluid, or, better, to the ethereal extract. Add a few cubic centimeters of glacial acetic acid to about 10 c.c. of the fluid; shake thoroughly with an equal volume of ether; decant, and apply the test to the ether. In case of dried stains upon cloth, wood, etc., dissolve the stain in distilled water and test the water, or press a piece of moist blotting-paper against the stain, and touch the paper with drops of the guaiac and the turpentine successively.
2. Teichmann's Test.—This depends upon the production of characteristic crystals of hemin. It is a sensitive test, and, when positive, is absolute proof of the presence of blood. A number of substances—lime, fine X. SPECIAL BLOOD PATHOLOGY The more conspicuous characteristics of the blood in various diseases have been mentioned in previous sections. Although the great majority of blood changes are secondary, there are a few blood conditions in which the changes are so prominent, or the etiology so obscure, that they are commonly regarded as blood diseases. These will receive brief consideration here. A. ANEMIA This is a deficiency of hemoglobin, or red corpuscles, or both. It is either primary or secondary. The distinction is based chiefly upon etiology, although each type presents a more or less distinctive blood-picture. Secondary anemia is that which is symptomatic of some other 1. Secondary Anemia.—The more important conditions which produce secondary or symptomatic anemia are: (a) Poor nutrition, which usually accompanies unsanitary conditions, poor and insufficient food, etc. (b) Acute infectious diseases, especially rheumatism and typhoid fever. The anemia is more conspicuous during convalescence. (c) Chronic infectious diseases: tuberculosis, malaria, syphilis, leprosy. (d) Chronic exhausting diseases, as heart disease, chronic nephritis, cirrhosis of the liver, and gastro-intestinal diseases, especially when associated with atrophy of gastric and duodenal glands. The last may give an extreme anemia, indistinguishable from pernicious anemia. (e) Chronic poisoning, as from lead, arsenic, and phosphorus. (f) Hemorrhage—either repeated small hemorrhages, as from gastric cancer and ulcer, uterine fibroids, etc., or a single large one. (g) Malignant tumors: these affect the blood partly through repeated small hemorrhages, partly through toxic products, and partly through interference with nutrition. (h) Animal Parasites.—Some cause no appreciable change in the blood; others, like the Uncinaria and Bothriocephalus latus, may produce a very severe anemia, almost identical with pernicious anemia. Anemia in these cases is probably due both to toxins and to abstraction of blood. The blood-picture varies with the grade of anemia. Although the number of leukocytes bears no relation to the anemia, leukocytosis is common, being due to the same cause. Stained films show no changes in very mild cases. In moderate cases variations in size and shape of the red cells and polychromatophilia occur. Very severe cases show the same changes to greater degree, with addition of basophilic degeneration and the presence of normoblasts in small or moderate numbers. Megaloblasts in very small numbers have been encountered in extremely severe cases. Blood-plaques are usually increased. 2. Primary Anemia.—The commonly described varieties of primary anemia are pernicious anemia and chlorosis, but splenic anemia may also be mentioned under this head. (1) Progressive Pernicious Anemia.—It is frequently impossible to diagnose this disease from the blood examination alone. Severe secondary anemia sometimes gives an identical picture. Remissions, in which the blood approaches the normal, are common. All the clinical data must, therefore, be considered. Hemoglobin and red corpuscles are always greatly diminished. In none of Cabot's 139 cases did the count exceed 2,500,000, the average being about 1,200,000. In more than two-thirds of the cases hemoglobin was The leukocyte count may be normal, but is commonly diminished to about 3000. The decrease affects chiefly the polymorphonuclear cells, so that the lymphocytes are relatively increased. In some cases a decided absolute increase of lymphocytes occurs. Polymorphonuclear leukocytosis, when present, is due to some complication.
The red corpuscles show marked variation in size and shape (Plate VIII and Fig. 84). There is a decided The rare and rapidly fatal anemia which has been described under the name of aplastic anemia is probably a variety of pernicious anemia. Absence of any attempt at blood regeneration explains the marked difference in the blood picture. Red corpuscles and hemoglobin are rapidly diminished to an extreme degree. The color index is normal or low. The leukocyte count is normal or low, with relative increase of lymphocytes. Stained smears show only slight variations in size, shape, and staining properties of the red cells. There are no megaloblasts, and few or no normoblasts. (2) Chlorosis.—The clinical symptoms furnish the most important data for diagnosis. The blood resembles that of secondary anemia in many respects. The most conspicuous feature is a decided decrease of hemoglobin (down to 30 or 40 per cent. in marked cases), accompanied by a slight decrease in number of red corpuscles. The color-index is thus almost invariably low, the average being about 0.5. As in pernicious anemia, the leukocytes are normal or decreased in number, with a relative increase of lymphocytes. (3) Splenic Anemia.—This is an obscure form of anemia associated with great enlargement of the spleen. It is probably a distinct entity. There is decided decrease of hemoglobin and red corpuscles, with moderate leukopenia and relative lymphocytosis. Osler's fifteen cases averaged 47 per cent. hemoglobin and 3,336,357 red cells. Stained films show notable irregularities in size, shape, and staining properties only in advanced cases. Erythroblasts are uncommon. B. LEUKEMIA Except in rare instances, diagnosis is easily made from the blood alone. Two types of the disease are commonly distinguished: the myelogenous and the lymphatic. Atypical and intermediate forms are not uncommon. Pseudoleukemia, because of its clinical similarity to lymphatic leukemia, is generally described along with leukemia. 1. Myelogenous Leukemia.—This is usually a chronic disease, although acute cases have been described. Hemoglobin and red corpuscles show decided decrease. The color-index is moderately low. Most striking is the immense increase in number of leukocytes. The count in ordinary cases varies between 100,000 and 300,000. Counts over 1,000,000 have been While these enormous leukocyte counts are equaled in no other disease, and approached only in lymphatic leukemia and extremely high-grade leukocytosis, the diagnosis, particularly during remissions, depends more upon qualitative than quantitative changes. Although all varieties are increased, the characteristic and conspicuous cell is the myelocyte. This cell never appears in normal blood; extremely rarely in leukocytosis; and never abundantly in lymphatic leukemia. In myelogenous leukemia myelocytes usually constitute more than 20 per cent. of all leukocytes. Da Costa's lowest case gave 7 per cent. The neutrophilic form is generally much more abundant than the eosinophilic. Both show considerable variations in size. Very constant also is a marked absolute, and often a relative, increase of eosinophiles and basophiles. Polymorphonuclear neutrophiles and lymphocytes are relatively decreased.
2. Lymphatic Leukemia.—This form may be either acute or chronic. There is marked loss of hemoglobin and red corpuscles. The color-index is usually moderately low. The leukocyte count is high, but lower than in the myelogenous type. Counts of 100,000 are about the average, but in many cases are much lower. This high The red corpuscles show the changes usual in severe secondary anemia. Erythroblasts are seldom abundant. Blood-plaques are decreased. 3. Pseudoleukemia (Hodgkin's disease) resembles lymphatic leukemia in that there is marked and progressive enlargement of the lymph-nodes. There is, however, no distinctive blood-picture. The changes in hemoglobin and red cells resemble those of a moderate symptomatic anemia, with rather low color-index. The leukocytes are commonly normal in number and relative proportions. 4. AnÆmia Infantum PseudoleukÆmica.—Under this name von Jaksch described a rare disease of infancy, the proper classification of which is uncertain. There is enlargement of liver and spleen, and sometimes of lymph-nodes, together with the following blood-changes: grave anemia with deformed and degenerated red cells and many erythroblasts of both normoblastic and megaloblastic types; great increase in number of leukocytes (20,000 to 100,000), and great variations in size, shape, and staining of leukocytes, with many atypical forms and a few myelocytes. The table on the following page contrasts the distinctive blood-changes in the more common conditions.
CHAPTER IVTHE STOMACHLaboratory methods may be applied to the diagnosis of stomach disorders in: I. Examination of the gastric contents removed with the stomach-tube. II. Certain other examinations which give information as to the condition of the stomach. Stomach digestion consists mainly in the action of pepsin upon proteids in the presence of hydrochloric acid and in the curdling of milk by rennin. Pepsin and rennin are secreted by the gastric glands as zymogens—pepsinogen and renninogen, respectively—which are converted into pepsin and rennin by hydrochloric acid. Hydrochloric acid is secreted by certain cells of the fundus glands. It at once combines loosely with the proteids of the food, forming acid-albumin, the first step in proteid digestion. Hydrochloric acid, which is thus loosely combined with proteids, is called "combined" hydrochloric acid. The acid which is secreted after the proteids present have all been converted into acid-albumin remains as "free" hydrochloric acid, and, together with pepsin, continues the process of digestion. At the height of digestion the stomach-contents consist essentially of: (1) Water; (2) free hydrochloric acid; (3) combined hydrochloric acid; (4) pepsin; (5) rennin;
A. OBTAINING THE CONTENTS Gastric juice is secreted continuously, but quantities sufficiently large for examination are not usually obtainable from the fasting stomach. In clinical work, therefore, it is desirable to stimulate secretion with food—which is the natural and most efficient stimulus—before attempting to collect the gastric fluid. Different foods stimulate secretion to different degrees; hence for the sake of uniform results certain standard "test-meals" have been 1. Test-meals.—It is customary to give the test-meal in the morning, since the stomach is most apt to be empty at that time. If it be suspected that the stomach will not be empty, it should be washed out with water the evening before. (1) Ewald's test-breakfast consists of a roll (or two slices of bread) without butter and two small cups (300 to 400 c.c.) of water or weak tea without cream or sugar. It should be well masticated. The contents of the stomach are to be removed one hour afterward. This test-meal is used for most routine examinations. Its disadvantage is that it introduces, with the bread, a variable amount of lactic acid and numerous yeast-cells. This source of error may be eliminated by substituting a shredded whole-wheat biscuit for the roll. (2) Boas' test-breakfast consists of a tablespoonful of rolled oats in a quart of water, boiled to one pint, with a pinch of salt added. It should be withdrawn in forty-five minutes to one hour. This meal does not contain lactic acid, and is usually given when detection of lactic acid is important, as in suspected gastric cancer. The stomach should always be washed with water the evening previous. 2. Withdrawal of the Contents.—The Boas stomach-tube, with bulb, is probably the most satisfactory form. It should be of rather large caliber, and have an opening in the tip and one or two in the side near the tip. When not in use, it should be kept in a vessel of borax solution, and should be well washed in hot water both before and after using. It is important confidently to assure the patient that introduction of the tube cannot possibly harm him; and The tube should be dipped in warm water just before using: the use of glycerin or other lubricant is undesirable. With the patient seated upon a chair, his clothing protected by towels or a large apron, and his head tilted forward, the tip of the tube, held as one would a pen, is introduced far back into the pharynx. He is then urged to swallow, and the tube is pushed boldly into the esophagus until the ring upon it reaches the incisor teeth, thus indicating that the tip is in the stomach. If, now, the patient cough or strain as if at stool, the contents of the stomach will usually be forced out through the tube. Should it fail, the fluid can generally be pumped out by alternate compression of the tube and the bulb. If unsuccessful at first, the attempts should be repeated with the tube pushed a little further in, or withdrawn a few inches, since the distance to the stomach is not the same in all cases. The tube may become clogged with pieces of food, in which case it must be withdrawn, cleaned, and reintroduced. If, after all efforts, no fluid is obtained, another test-meal should be given and withdrawn in forty-five minutes. As the tube is removed, it should be pinched between the fingers so as to save any fluid that may be in it. The stomach-tube must be used with great care, or not at all, in cases of gastric ulcer, aneurysm, uncompensated heart disease, and marked arteriosclerosis. Except in gastric ulcer, the danger lies in the retching produced, and the tube can safely be used if the patient takes it easily. B. PHYSICAL EXAMINATION Under normal conditions, 30 to 50 c.c. of fluid can be obtained one hour after administering Ewald's breakfast. More than 60 c.c. points to motor insufficiency; less than 20 c.c., to too rapid emptying of the stomach, or else to incomplete removal. Upon standing, it separates into two layers, the lower consisting of particles of food, the upper of an almost clear, faintly yellow fluid. The extent to which digestion has taken place can be roughly judged from the appearance of the food-particles. The reaction is frankly acid in health and in nearly all pathologic conditions. It may be neutral or slightly alkaline in some cases of gastric cancer and marked chronic gastritis, or when contaminated by a considerable amount of saliva. A small amount of mucus is present normally. Large amounts, when the gastric contents are obtained with the tube and not vomited, point to chronic gastritis. Mucus is recognized from its characteristic slimy appearance when the fluid is poured from one vessel into another. A trace of bile may be present as a result of excessive straining while the tube is in the stomach. Larger amounts are very rarely found, and generally point to obstruction in the duodenum. Bile produces a yellowish or greenish discoloration of the fluid. Blood is often recognized by simple inspection, but more frequently requires a chemic test. It is bright red when very fresh, and dark, resembling coffee-grounds, when older. Particles of food eaten hours, or even days, previously, may be found, and indicate deficient motor power. C. CHEMIC EXAMINATION A routine chemic examination of the gastric contents involves qualitative tests for free acids, free hydrochloric acid, and organic acids, and quantitative estimations of total acidity, free hydrochloric acid, and sometimes combined hydrochloric acid. Other tests are applied when indicated. 1. Qualitative Tests.—(1) Free Acids.—The presence or absence of free acids, without reference to the kind, is easily determined by means of Congo-red.
(2) Free Hydrochloric Acid.—In addition to its digestive function, free hydrochloric acid is an efficient antiseptic. It prevents or retards fermentation and lactic-acid formation, and is an important means of protection against the entrance of pathogenic organisms into the body. It is never absent in health.
(3) Organic Acids.—Lactic acid is the most common, and is taken as the type of the organic acids which appear in the stomach-contents. It is a product of bacterial activity. Acetic and butyric acids are sometimes present. Their formation is closely connected with that of lactic acid, and they are rarely tested for. When abundant, they may be recognized by their odor upon heating. Lactic acid is never present at the height of digestion in health. Although usually present early in digestion, it disappears when free hydrochloric acid begins to appear. As already stated, the Ewald test-breakfast introduces a small amount of lactic acid, but rarely enough to respond to the tests given here. In every case, however, in which its detection is important, Boas' test-breakfast should be given, the stomach having been thoroughly washed the evening before.
(4) Pepsin and Pepsinogen.—Pepsinogen itself has no digestive power. It is secreted by the gastric glands, and is transformed into pepsin by the action of a free acid. Although pepsin digests proteids best in the presence of free hydrochloric acid, it has a slight digestive activity in the presence of organic or combined hydrochloric acids. The amount is not influenced by neuroses or circulatory disturbances. Absence or marked diminution, therefore, indicates organic disease of the stomach. It is an important point in diagnosis between functional and organic conditions. Pepsin is rarely or never absent in the presence of free hydrochloric acid.
(5) Rennin and Renninogen.—Rennin is the milk-curdling ferment of the gastric juice. It is derived from renninogen through the action of hydrochloric acid. Lime salts also possess the power of transforming renninogen into the active ferment. Deficiency of rennin has the same significance as deficiency of pepsin, and is more easily recognized. Since the two enzyms are almost invariably present or absent together, the test for rennin serves also as a test for pepsin.
(6) Blood.—Blood is present in the vomitus in a great variety of conditions. When found in the fluid removed after a test-meal, it commonly points toward ulcer or carcinoma. Blood can be detected in nearly one-half of the cases of gastric cancer. The presence of swallowed blood must be excluded.
2. Quantitative Tests.—(1) Total Acidity.—The acid-reacting substances which contribute to the total acidity are free hydrochloric acid, combined hydrochloric acid, acid salts, mostly phosphates, and, in some pathologic conditions, the organic acids. The total acidity is normally about 50 to 75 degrees (see method below), or, when estimated as hydrochloric acid, about 0.2 to 0.3 per cent.
(2) Hydrochloric Acid.—After the Ewald and Boas test-breakfasts, the amount of free hydrochloric acid varies normally between 25 and 50 degrees, or about 0.1 to 0.2 per cent. In disease, it may go considerably higher, or may be absent altogether. When the amount of free hydrochloric acid is normal, organic disease of the stomach probably does not exist. Increase of free hydrochloric acid above 50 degrees Decrease of free hydrochloric acid below 25 degrees (hypochlorhydria) occurs in some neuroses, chronic gastritis, early carcinoma, and most conditions associated with general systemic depression. Marked variation in the amount at successive examinations strongly suggests a neurosis. Too low values are often obtained at the first examination, the patient's dread of the introduction of the tube probably inhibiting secretion. Absence of free hydrochloric acid (achlorhydria) occurs in most cases of gastric cancer and far-advanced chronic gastritis, in many cases of pernicious anemia, and, sometimes, in hysteria. The presence of free hydrochloric acid presupposes a normal amount of combined hydrochloric acid, hence the combined need not be estimated when the free acid has been found. When, however, free hydrochloric acid is absent, it is important to know whether any acid is secreted, and an estimation of the combined acid then becomes of great value. The normal average after an Ewald breakfast is about 10 to 15 degrees.
(3) Organic Acids.—There is no simple direct quantitative method. After the total acidity has been (4) Pepsin.—No direct method is available. The following is sufficient for clinical purposes:
D. MICROSCOPIC EXAMINATION A drop of unfiltered stomach-contents is placed upon a slide, covered with a cover-glass, and examined with the two-thirds and one-sixth objectives. Under normal conditions little is to be seen except great numbers of starch-granules, with an occasional epithelial cell, yeast-cell, or bacterium. Starch-granules are recognized by their concentric striations and the fact that they stain blue with iodin solutions.
Pathologically, remnants of food from previous meals, red blood-corpuscles, pus-cells, sarcinÆ, and excessive numbers of yeast-cells and bacteria may be encountered (Fig. 88). Remnants of food from previous meals indicate deficient gastric motility. Red Blood-corpuscles.—Blood is best recognized by the chemic tests already given. The corpuscles Pus-cells.—Pus is rarely encountered in the fluid removed after a test-meal. Considerable numbers of pus-corpuscles have been found in some cases of gastric cancer. Swallowed sputum must always be considered. SarcinÆ.—These are small spheres arranged in cuboid groups often compared to bales of cotton. They frequently form large clumps and are easily recognized. They stain brown with iodin solution. They signify fermentation. Their presence is strong evidence against the existence of gastric cancer, in which disease they rarely occur. Yeast-cells.—As already stated, a few yeast-cells may be found under normal conditions. The presence of considerable numbers is evidence of fermentation. Their appearance has been described (p. 130). They stain brown with iodin solution.
Bacteria.—Numerous bacteria may be encountered, especially in the absence of free hydrochloric acid. The Boas-Oppler bacillus is the only one of special significance. These bacilli (Fig. 89) are large (5 to 10 µ long), non-motile, and usually arranged end to end in chains. They stain brown with iodin solution, which distinguishes them from Leptothrix buccalis (p. 270), which is not infrequently found in stomach fluid. They also stain by Gram's method. They are easily seen with the one-sixth objective in unstained preparations, but are best recognized with the one-twelfth, after drying some of the fluid upon a cover-glass, fixing, and staining with LÖffler's methylene-blue or by Gram's method. A few large non-motile bacilli are frequently seen; they cannot be called Boas-Oppler bacilli unless they are numerous and show something of the typical arrangement. E. THE GASTRIC CONTENTS IN DISEASE In the diagnosis of stomach disorders the practitioner must be cautioned against relying too much upon examinations of the stomach-contents. A first examination is especially unreliable. Even when repeated examinations are made, the laboratory findings must never be considered apart from the clinical signs. The more characteristic findings in certain disorders are suggested here. 1. Dilatation of the Stomach.—Evidences of retention and fermentation are the chief characteristics of this condition. Hydrochloric acid is commonly diminished. Pepsin may be normal or slightly diminished. Lactic acid may be detected in small amounts, but is usually absent when the stomach has been washed before giving the 2. Gastric Neuroses.—The findings are variable. Successive examinations may show normal, increased, or diminished hydrochloric acid, or even entire absence of the free acid. Pepsin is usually normal. In the neurosis characterized by continuous hypersecretion (gastrosuccorrhea), 40 c.c. or more of gastric juice can be obtained from the fasting stomach. Should the fluid contain food-particles, it is probably the result of retention, not hypersecretion. 3. Chronic Gastritis.—Free hydrochloric acid may be increased in early cases. It is generally diminished in well-marked cases, and is often absent in advanced cases. Lactic acid is often present in traces, rarely in notable amount. Secretion of pepsin and rennin is always diminished in marked cases. Mucus is frequently present, and is very significant of the disease. Motility and absorption are generally deficient. Small fragments of mucous membrane may be found, and when examined by a pathologist, may occasionally establish the diagnosis. 4. Achylia Gastrica (Atrophic Gastritis).—This condition may be a terminal stage of chronic gastritis. It is sometimes associated with the blood-picture of pernicious anemia. It gives a great decrease, and sometimes entire absence of hydrochloric acid and ferments. The total acidity may be as low as 1 or 2 degrees. Small amounts of lactic acid may be present. Absorption and motility are usually not affected. It is probable that some substance is produced by the cancer which neutralizes the free hydrochloric acid, and thus causes it to disappear earlier than in other organic diseases of the stomach. The presence of lactic acid is the most suggestive single symptom of gastric cancer. In the great majority of cases its presence in notable amount (0.1 per cent. by Strauss' method) after Boas' breakfast, the stomach having been washed the evening before, warrants a diagnosis of malignancy. Carcinoma seems to furnish an especially favorable medium for the growth of the Boas-Oppler bacillus, hence this micro-organism is frequently present. Blood can be detected in the stomach fluid by the chemic tests in nearly one-half of the cases, and is more common when the newgrowth is situated at the pylorus. Blood is present in the stool in nearly every case. Evidences of retention and fermentation are the rule in pyloric cancer. Tumor particles are sometimes found late in the disease. 6. Gastric Ulcer.—There is excess of free hydrochloric acid in about one-half of the cases. In other cases the acid is normal or diminished. Blood is often present. The diagnosis must be based largely upon the clinical symptoms, and where ulcer is strongly suspected, it is probably unwise to use the stomach-tube. II. ADDITIONAL EXAMINATIONS WHICH GIVE INFORMATION AS TO THE CONDITION OF THE STOMACH 1. Absorptive Power of the Stomach.—This is a very unimportant function, only a few substances being absorbed in the stomach. It is delayed in most organic diseases of the stomach, especially in dilatation and carcinoma, but not in neuroses. The test has little practical value.
2. Motor Power of the Stomach.—This refers to the rapidity with which the stomach passes its contents on into the intestine. It is very important: intestinal digestion can compensate for insufficient or absent stomach digestion only so long as the motor power is good. Motility is impaired to some extent in chronic gastritis. It is especially deficient in dilatation of the stomach due to atony of the gastric wall or to pyloric obstruction, either benign or malignant. It is increased in most conditions with hyperchlorhydria. The best evidence of deficient motor power is the detection of food in the stomach at a time when it should be empty, e.g., before breakfast in the morning. When more than 60 c.c. of fluid are obtained with the tube one hour after a Ewald breakfast, deficient motility may be inferred.
3. To Determine Size and Position of Stomach.—After removing the test-meal, while the tube is still in place, force quick puffs of air into the stomach by compression of the bulb. The puffs can be clearly heard with a stethoscope over the region of the stomach, and nowhere else. If desired, the patient may be given a dram of sodium bicarbonate in solution, followed immediately by the same amount of tartaric acid, also in solution; or he may take the two parts of a seidlitz powder separately. The carbon dioxid evolved distends the stomach, and its outline can easily be determined by percussion. CHAPTER VTHE FECESAs commonly practised, an examination of the feces is limited to a search for intestinal parasites or their ova. Much of value can, however, be learned from other simple examinations, particularly a careful inspection. Anything approaching a complete analysis is, on the other hand, a waste of time for the clinician. The normal stool is a mixture of—(a) Water; (b) undigested and indigestible remnants of food, as starch-granules, particles of meat, plant-cells and fibers, etc.; (c) digested foods, carried out before absorption could take place; (d) products of the digestive tract, as altered bile-pigments, mucus, etc.; (e) products of decomposition, as indol, skatol, fatty acids, and various gases; (f) epithelial cells shed from the wall of the intestinal canal; (g) harmless bacteria, which are always present in enormous numbers. Pathologically, we may find abnormal amounts of normal constituents, blood, pathogenic bacteria, animal parasites and their ova, and biliary and intestinal concretions. The stool to be examined should be passed into a clean vessel, without admixture of urine. The offensive odor can be partially overcome with turpentine or 5 per cent. phenol. When search for Amoeba coli is to be made, the vessel must be warm, and the stool kept warm until examined; naturally, no disinfectant can be used. I. MACROSCOPIC EXAMINATION 1. Quantity.—The amount varies greatly with diet and other factors. The average is about 100 to 150 gm. in twenty-four hours. 2. Frequency.—One or two stools in twenty-four hours may be considered normal, yet one in three or four days is not uncommon with healthy persons. The individual habit should be considered in every case. 3. Form and Consistence.—Soft, mushy, or liquid stools follow cathartics and accompany diarrhea. Copious, purely serous discharges without fecal matter are significant of Asiatic cholera, although sometimes observed in other conditions. Hard stools accompany constipation. Rounded scybalous masses are common in habitual constipation, and indicate atony of the muscular coat of the intestine. Flattened, ribbon-like stools result from some obstruction in the rectum, generally a tumor or stricture from a healed ulcer, most commonly syphilitic. When bleeding piles are absent, blood-streaks upon such a stool point to carcinoma. 4. Color.—The normal light or dark-brown color is due chiefly to altered bile-pigments. The stools of infants are yellow, owing partly to their milk diet and partly to the presence of unchanged bilirubin. Diet and drugs cause marked changes: milk, a light yellow color; cocoa and chocolate, dark gray; various fruits, reddish or black; iron and bismuth, dark brown or black; hematoxylin, red; etc. Pathologically, the color is important. A golden yellow is generally due to unchanged bilirubin. Green stools are not uncommon, especially in diarrheas of childhood. The color is due to biliverdin, or, sometimes, to Notable amounts of blood produce tarry black stools when the source of the hemorrhage is the stomach or upper intestine, and a dark brown or bright red as the source is nearer the rectum. When diarrhea exists, the color may be red, even if the source of the blood is high up. Red streaks of blood upon the outside of the stool are due to lesions of rectum or anus. 5. Odor.—Products of decomposition, chiefly indol and skatol, are responsible for the normal offensive odor. A sour odor is normal for nursing infants, and is noted in mild diarrheas of older children. In the severe diarrheas of childhood a putrid odor is common. In adults stools emitting a very foul stench are suggestive of malignant or syphilitic ulceration of the rectum or gangrenous dysentery. 6. Mucus.—Excessive quantities of mucus are easily detected with the naked eye, and signify irritation or inflammation. When the mucus is small in amount and intimately mixed with the stool, the trouble is probably in the small intestine. Larger amounts, not well mixed with fecal matter, indicate inflammation of the large intestine. Stools composed almost wholly of mucus and streaked with blood are the rule in dysentery, ileocolitis, and intussusception. In the so-called mucous colic, or membranous enteritis, shreds and ribbons of altered mucus, sometimes representing complete casts of the bowel, are passed. Concretions can be found by breaking up the fecal matter in a sieve (which may be improvised from gauze) while pouring water over it. It must be remembered that gall-stones, if soft, may go to pieces in the bowel. 8. Animal Parasites.—Segments of tape-worms and the adults and larvÆ of other parasites are often found in the stool. They are best searched for in the manner described for concretions. The search should be preceded by a vermicide and a brisk purge. Patients frequently mistake vegetable tissue (long fibers from poorly masticated celery or "greens," cells from orange, etc.) for intestinal parasites, and the writer has known physicians to make similar mistakes. Even slight familiarity with the microscopic structure of vegetable tissue will prevent the chagrin of such errors. Complicated chemic examinations are of little value to the clinician. Certain tests are, however, important. 1. Blood.—When present in large amount, blood produces such changes in the appearance of the stool that it is not likely to be overlooked. Traces of blood (occult hemorrhage) can be detected only by special tests. Recognition of occult hemorrhage has its greatest value in diagnosis of gastric cancer and ulcer. It is constantly present in practically every case of gastric cancer, and is always present, although usually intermittently, in ulcer. Traces of blood also accompany malignant disease of the
2. Bile.—Normally, unaltered bile-pigment is never present in the feces of adults. In catarrhal conditions of the small intestine bilirubin may be carried through unchanged. It may be demonstrated by filtering (after mixing with water if the stool be solid) and testing the filtrate by Gmelin's method, as described under The Urine. III. MICROSCOPIC EXAMINATION Care must be exercised in selection of portions for examination. A random search will often reveal nothing of interest. A small bit of the stool, or any suspicious-looking particle, is placed upon a slide, softened with water if necessary, and pressed out into a thin layer with a cover-glass. A large slide—about 2 by 3 inches—with a correspondingly large cover will be found convenient. Most of the structures which it is desired to see can be found with a two-thirds objective. Details of structure must be studied with a higher power.
1. Remnants of Food.—These include a great variety of structures which are very confusing to the student. Considerable study of normal feces is necessary for their recognition. Vegetable fibers are generally recognized from their spiral structure; vegetable cells, from their double contour and the chlorophyl bodies which many of them contain. These cells are apt to be mistaken for the ova of parasites. Starch-granules sometimes retain their original form, but are ordinarily not to be recognized except by their staining reaction. They strike a blue color with Lugol's solution when undigested; a red color, when slightly digested. Muscle-fibers are yellow, and sometimes appear as short, Excess of any of these structures may result from excessive ingestion or deficient intestinal digestion. 2. Epithelial Cells.—A few cells derived from the wall of the alimentary canal are a constant finding. They show all stages of degeneration, and are often unrecognizable. A marked excess has its origin in a catarrhal condition of some part of the bowel. Squamous cells come from the anal orifice; otherwise the form of the cells gives no clue to the location of the lesion. 3. Pus.—Amounts of pus sufficient to be recognized with the eye alone indicate rupture of an abscess into the bowel. If well mixed with the stool, the source is high up, but in such cases the pus is apt to be more or less completely digested, and hence unrecognizable. Small amounts, detected only by the microscope, are present in catarrhal and ulcerative conditions of the intestine, the number of pus-cells corresponding to the severity and extent of the process. 4. Blood-corpuscles.—Unaltered red corpuscles are rarely found unless their source is near the anus. Ordinarily, only masses of blood-pigment can be seen. Blood is best recognized by the chemic tests (p. 239). 5. Bacteria.—In health, bacteria constitute about one-third of the weight of the dried stool. They are beneficial to the organism, although not actually necessary In some pathologic conditions the character of the intestinal flora changes so that Gram-staining bacteria very greatly predominate. As shown by R. Schmidt, of Neusser's clinic in Vienna, this change is most constant and most striking in cancer of the stomach, owing to large numbers of Boas-Oppler bacilli, and is of considerable value in diagnosis. He believes that a diagnosis of gastric carcinoma should be very unwillingly made with an exclusively "Gram-negative" stool, while a "Gram-positive" stool, due to bacilli (which should also stain brown with Lugol's solution), may be taken as very strong evidence of cancer. A Gram-positive stool due to cocci is suggestive of intestinal ulceration. The technic is the same as when Gram's method is applied to other material (p. 40), except that the smear is fixed by immersion in methyl-alcohol for five minutes instead of by heat. Fuchsin is the best counter-stain. The deep-purple Gram-staining bacteria stand out much more prominently than the pale-red Gram-negative organisms, and one may be misled into thinking them more numerous even in cases in which they are much in the minority. The number of Boas-Oppler bacilli can be increased by administering a few ounces of sugar of milk the day before the examination. Owing to the difficulty of excluding swallowed sputum, the presence of the tubercle bacillus is less significant in the feces than in other material. It may, however, be taken as evidence of intestinal tuberculosis when clinical signs indicate an intestinal lesion and reasonable care is 6. Crystals.—Various crystals may be found, but few have any significance. Slender, needle-like crystals of fatty acids and soaps (Fig. 32) and triple phosphate crystals (Fig. 90) are common. Characteristic octahedral crystals of calcium oxalate (Fig. 47) appear after ingestion of certain vegetables. Charcot-Leyden crystals (Fig. 6) are not infrequently encountered, and strongly suggest the presence of intestinal parasites. Yellowish or brown, needle-like or rhombic crystals of hematoidin (Fig. 32) may be seen after hemorrhage into the bowel. 7. Ova of Parasites.—The stool should be well mixed with water and allowed to settle. The ova will be found in the upper or middle portions of the sediment. Descriptions will be found in the following chapter. CHAPTER VIANIMAL PARASITESAnimal parasites are common in all countries, but are especially abundant in the tropics, where almost every native is host for one or more varieties. Because of our growing intercourse with these regions, the subject is assuming increasing importance in this country. Many parasites, hitherto comparatively unknown here, will probably become common. Some parasites produce no symptoms, even when present in large numbers. Others cause very serious symptoms. Only those which have clinical interest will be considered here. The illustrations will give a better idea of their appearance than any description. They belong to three classes: I. Protozoa. II. Vermes. III. Arthropoda. I. PROTOZOA 1. Amoeba Coli DysenteriÆ.—This organism is found, often in large numbers, in the stools of tropical dysentery and in the pus and walls of hepatic abscesses associated with dysentery, and is generally regarded as the cause of the disease. It is a colorless, granular cell, 20 to 40 µ in diameter (Fig. 91). It contains one or more distinct vacuoles; a round nucleus, which ordinarily is obscured by the granules; and frequently red blood-corpuscles and bacteria. When at rest, its shape is spheric; but upon a warm slide it exhibits the characteristic ameboid motion,
When the presence of amebÆ is suspected, the stool should be passed into a warm vessel and kept warm until and during the examination. A warm stage can be improvised from a plate of copper with a hole cut in the center. This is placed upon the stage of the microscope, and one of the projecting ends is heated with a small flame. AmebÆ are most likely to be found in grayish or blood-streaked particles of mucus. Favorable material for examination can be obtained at one's convenience by inserting into the rectum a large catheter with roughly cut lateral openings. A sufficient amount of mucus or fecal matter will usually be brought away by it. 2. Trichomonas Vaginalis.—The acid discharge of catarrhal vaginitis sometimes contains this parasite in
A similar but somewhat smaller organism, Cercomonas hominis (Fig. 93), has been found in the feces in a variety of diarrheal conditions and in from 10 to 25 per cent. of healthy persons in tropical regions.
In urine or vaginal discharges these organisms might be mistaken for spermatozoa by one who is entirely unfamiliar with the appearance of either. 3. Paramoecium Coli (Balantidium Coli).—This parasite is an occasional inhabitant of the colon of man, and sometimes produces diarrhea. It is an oval organism, about 0.1 mm. long, is covered with cilia, and contains
4. Hemosporidia.—This is a large group of parasites with two life-cycles: one in the blood-corpuscles or plasma of a vertebrate host—man, mammals, birds, reptiles; the other in the body of some insect. The malarial parasite, already described; the organism (Pirosoma bigeminum) producing Texas fever in cattle; and the questionable parasite (Piroplasma hominis), which has been described as the cause of "tick fever" of Montana, belong to the group. 5. Trypanosomes have been mentioned (p. 195). II. VERMES 1. Cestoda.—Tape-worms are very common parasites of both man and the animals. The most important are TÆnia saginata, TÆnia solium, Bothriocephalus latus, and TÆnia echinococcus. They all pass a larval stage in the body of an intermediate host. In the adult stage they consist of a linear series of flat, rectangular segments (proglottides), at one end of which is a smaller segment, the scolex or head, especially adapted for attachment to the host. The series represents a colony, of which the
(1) TÆnia Saginata or Mediocanellata (Fig. 95).—This, the beef tape-worm, is the common tape-worm of the United States. Its length sometimes exceeds twenty-five feet. The middle segments measure about one-fourth by one-half inch. The scolex is about the size of a pin-head, and is surrounded by four sucking discs, but has no hooklets (Fig. 96). The uterus extends along the middle line of the segment and gives off about twenty branches upon each side (Fig. 100). The larval stage is passed in the muscles of various animals, especially cattle, where it lies encysted (cysticercus stage). The larva is ingested with the meat, its capsule is The ova are present in the stools of infected persons, often in great numbers. They are spheric or ovoid, yellow in color, and have a thick, radially striated shell (Fig. 101). Their greatest diameter is 30 to 40 µ (about four or five times the diameter of a red blood-corpuscle). Vegetable cells, which are generally present in the feces, are often mistaken for them.
(2) TÆnia solium, the pork tape-worm is very rare in this country. It is usually much shorter than TÆnia saginata. The scolex is surrounded by four sucking discs, and has a projection, or rostellum, with a double row of horny hooklets (Fig. 97). The uterus has only seven to ten branches (Fig. 100). The ova closely resemble those of TÆnia saginata, but are a little smaller (Fig. 101). (3) Bothriocephalus latus, the fish tape-worm, is the largest parasite of man, sometimes reaching fifty feet in
The larval stage is found in fish, especially the pike.
The ova are characteristic. They measure about 45 by 70 µ, are brown in color, and are filled with small spherules. The shell is thin, and has a small hinged lid at one end (Fig. 99).
(4) TÆnia Echinococcus.—The mature form of this tape-worm inhabits the intestine of the dog and wolf. The larvÆ develop in cattle and sheep ordinarily, but are The adult parasite is 2.5 to 5 mm. long, and consists of only four segments (Fig. 102). It contains many ova. When the ova reach the digestive tract of man, the embryos are set free and find their way to the liver, lung, or other organ, where they develop into cysts, thus losing their identity. Other cysts, called "daughter cysts," are formed within these. The cyst-wall is made up of two layers, from the inner of which develop larvÆ which are identical with the head, or scolex, of the mature parasite. These are ovoid structures about 0.3 mm. long. Each has four lateral suckers and a rostellum surmounted by a double circular row of horny hooklets. The rostellum with its hooklets is frequently invaginated into the body. Diagnosis of echinococcus disease depends upon detection of scolices, free hooklets, or particles of cyst-wall, which is characteristically laminated and usually has
The cyst-fluid is clear, between 1.002 and 1.010 in specific gravity, and contains a notable amount of sodium chlorid, but no albumin. 2. Nematoda.—(1) Ascaris Lumbricoides.—The female is 20 to 40 cm. long and about 6 mm. thick; the male, a little more than half as large. Their color is reddish or brown. They are the common "round-worms" so frequently found in children. Their habitat is the small intestine. Large numbers are sometimes present.
The diagnosis is made by detection of the worms or ova in the feces. The latter are generally numerous. They are elliptic, measuring about 50 by 70 µ, and have an unsegmented protoplasm (Fig. 105). The shell is thick, and is surrounded by an uneven gelatinous envelop which is often stained with bile.
(2) Oxyuris Vermicularis.—This is the "thread-worm" or "pin-worm" which inhabits the colon and rectum, especially of young children. Its presence should
The worms are not infrequently found in the feces; the ova, rarely. The latter are best found by scraping the skin at the margins of the anus, where they are deposited by the female. They are asymmetrically oval, about 50 µ in length, and often contain a partially developed embryo. (3) Filaria Sanguinis Hominis.—A description of this worm will be found in the chapter upon the Blood, p. 194. The embryos are sometimes found in urine and chylous fluids from the serous cavities. Their motion is then usually less active than when in blood. That shown in Fig. 107 was alive sixty hours after removal of the fluid. Embryos were present in the blood of the same patient.
(4) Trichina (Trichinella) Spiralis.—This is a very small worm, not exceeding 3 mm. in length when fully developed. Infection in man occurs from ingestion of insufficiently cooked pork, which contains encysted embryos. These reach maturity in the small intestine. The female produces great numbers of young, which Trichiniasis is generally accompanied by a marked eosinophilia. The diagnosis is made by teasing out upon a slide a bit of muscle, obtained preferably from the outer head of the gastrocnemius, the insertion of the deltoid, or the lower portion of the biceps. The coiled embryos can easily be seen with a two-thirds objective (Fig. 108).
(5) Uncinaria.—The two varieties of this worm, Uncinaria duodenalis and Uncinaria Americana, are among the more harmful of the animal parasites. They inhabit the small intestine, usually in great numbers, and commonly produce a severe and often fatal anemia. Infection is common in subtropical regions, notably in Egypt, in some European countries, and, especially, in Porto Rico and the West Indies, where about 90 per cent. of the rural population is infected. It is much more The adult worms are seldom found in the feces, but may appear after a dose of thymol followed by a brisk purge. They resemble Oxyuris vermicularis to the naked eye. Ova are usually present in enormous numbers. Those of Uncinaria duodenalis measure about 30 by 50 µ; of Uncinaria Americana, somewhat more. They have a thin, smooth, transparent shell, and their protoplasm is divided into 2, 4, 8, or more rounded segments (Fig. 110).
(6) Strongyloides Intestinalis.—Infection with this worm is by no means so rare in this country as the few clinical reports would indicate. It is very common in subtropical countries, notably in Italy and in southern China. It seems probable that the parasite is the cause
The adult worm, which reproduces by parthenogenesis, is about 2 mm. long. It inhabits the upper portion of the small intestine, but neither it nor the ova appear in the stool unless an active diarrhea exists. Ordinarily the eggs hatch in the intestine, and when infection is severe, embryos can be found in the feces in large numbers. These are the "rhabditiform embryos," which measure about 0.40 by 0.02 mm. They are actively motile, and are best found by making a small depression in the fecal mass, filling it with water, and standing in a warm place (preferably an incubator) for twelve to twenty-four hours. The embryos will collect in the water, and can be easily found with a two-thirds objective. Outside the body the rhabditiform embryos develop into a free-living, sexually differentiated generation. The young of this generation are the more slender "filariform embryos" (Fig. 111). Infection can occur either through these embryos of the free-living generation, or by direct transformation of rhabditiform into filariform embryos and these into the parthenogenic parasitic adult. (7) Trichocephalus Dispar (T. Trichiurus).—This,
The number present is usually small. The worms themselves are rarely found in the feces. The ova, which are not often abundant, are easily recognized. They are brown, ovoid in shape, about 50 µ long, and have a button-like projection at each end (Fig. 101). III. ARTHROPODA Most of these are external parasites, and the reader is referred to the standard works upon diseases of the skin for descriptions. The itch-mite (Acarus scabiei) and the louse (Pediculus capitis, corporis, vel pubis) are the more common members of the group. CHAPTER VIIMISCELLANEOUS EXAMINATIONSPUS Pus contains much granular dÉbris and numerous more or less degenerated cells, the great majority being polymorphonuclear leukocytes—so-called "pus-corpuscles." Eosinophilic leukocytes are common in gonorrheal pus and in asthmatic sputum. Examination of pus is directed chiefly to detection of bacteria. When very few bacteria are present, culture methods must be resorted to, but such methods do not come within the scope of this work. When considerable numbers are present, they can be detected and often identified in cover-glass smears. Several smears should be made, dried, and fixed as described under Sputum (p. 32). One of these should be stained one-fourth to one-half minute with LÖffler's methylene-blue, rinsed well with water, dried, mounted, and examined with an oil-immersion lens. This will show all bacteria except the tubercle bacillus, and often no other stain is necessary for their identification. In many cases special stains must be applied. Gram's method (p. 40) is a very useful aid in distinguishing certain bacteria. The more important organisms react to this staining method as follows:
The most common pus-producing organisms are staphylococci and streptococci. They are both cocci, or spheres, their average diameter being about 1 µ. Staphylococci are commonly grouped in clusters, often compared to bunches of grapes (Fig. 113). There are several varieties, which can be distinguished only in cultures. Streptococci are arranged side by side, forming chains of variable length (Fig. 114). Sometimes there are only three or four individuals in a chain; sometimes a chain
Should bacteria resembling pneumococci be found, Buerger's method (p. 37) should be tried. When it is inconvenient to stain before the smears have dried, capsules can be shown by the method of Hiss. The dried and fixed smear is covered with a stain composed of 5 c.c. saturated alcoholic solution gentian-violet and 95 c.c. distilled water, and heated until steam rises. The preparation is then washed with 20 per cent. solution of copper sulphate, dried, and mounted in Canada balsam. Pneumococci may give rise to inflammations in many locations. When they form short chains, demonstration of the capsule is necessary to distinguish them from streptococci. If tuberculosis be suspected, the smears should be stained by one of the methods for the tubercle bacillus (pp. 32 and 127), or guinea-pigs may be inoculated.
Gonococci, when typical, can usually be identified with sufficient certainty for clinical purposes in the smear stained with LÖffler's methylene-blue. They are coffee-bean-shaped cocci which lie in pairs with their flat surfaces together (Fig. 116). They lie for the most part within pus-cells, an occasional cell being filled with them, while the surrounding cells contain few or none. A few are Gonococci are generally easily found in pus from untreated acute and subacute gonorrheal inflammations,—conjunctivitis, urethritis, etc.,—but are found with difficulty in pus from chronic inflammations and abscesses, and in urinary sediments. PERITONEAL, PLEURAL, AND PERICARDIAL FLUIDS The serous cavities contain very little fluid normally, but considerable quantities are frequently present as a result of pathologic conditions. The pathologic fluids are classed as transudates and exudates. Transudates are non-inflammatory in origin. They contain only a few cells, and less than 2.5 per cent. of albumin, and do not coagulate spontaneously. The specific gravity is below 1018. Micro-organisms are seldom present. Exudates are of inflammatory origin. They are richer in cells and albumin, and tend to coagulate upon standing. The specific gravity is above 1018. Bacteria are generally present, and often numerous. The amount of albumin is estimated by Esbach's method, after diluting the fluid. Bacteria are recognized by cultures, animal inoculation, or stained smears. Exudates are usually classed as serous, serofibrinous, seropurulent, purulent, putrid, and hemorrhagic, which Cytodiagnosis.—This consists in a differential count of the cells in a transudate or exudate, particularly one of pleural or peritoneal origin.
The fresh fluid, obtained by aspiration, is centrifugalized for at least five minutes; the supernatant liquid is poured off; and cover-glass smears are made and dried in the air. The smears are then stained with Wright's blood-stain, to which one-third its volume of pure methyl-alcohol has
Predominance of polymorphonuclear leukocytes (pus-corpuscles) points to an acute infectious process (Fig. 117). Predominance of lymphocytes (Fig. 118) generally signifies tuberculosis. Tuberculous pleurisy due to direct extension from the lung may give excess of polymorphonuclears owing to mixed infection. Predominance of endothelial cells, few cells of any kind being present, indicates a transudate (Fig. 119). Endothelial cells generally predominate in carcinoma, but are accompanied by considerable numbers of lymphocytes and red blood-corpuscles. Examination of the fluid obtained by lumbar puncture is of value in diagnosis of certain forms of meningitis. Tubercle bacilli can be found in the majority of cases of tuberculous meningitis. The sediment, obtained by thorough centrifugalization or by coagulation and digestion (p. 128) is spread upon slides and stained by one of the methods already given. A considerable number of smears should be examined. In doubtful cases, inoculation of guinea-pigs must be resorted to. The Diplococcus intracellularis meningitidis is recognized as the cause of epidemic cerebrospinal fever, and can be detected in the cerebrospinal fluid of most cases, especially those which run an acute course. Cover-glass smears from the sediment should be stained by the method for the gonococcus. The meningococcus is an intracellular diplococcus which often cannot be distinguished
Various organisms have been found in other forms of meningitis—the pneumococcus most frequently. In some cases no micro-organisms can be detected even by culture methods. ANIMAL INOCULATION Inoculation of animals is one of the most reliable means of verifying the presence of certain micro-organisms in fluids and other material. Clinically, it is applied almost exclusively to demonstration of the tubercle bacillus when other means have The animals should be killed at the end of six or eight weeks, if they do not die before that time, and a careful postmortem examination should be made for the characteristic pearly-gray or yellow tubercles scattered over the peritoneum and through the abdominal organs, particularly the spleen, and for caseous inguinal and retroperitoneal lymph-glands. The tubercles and portions of the caseous glands should be crushed between two slides, dried, and stained for tubercle bacilli. The bacilli are difficult to find in the caseous material. THE MOUTH Micro-organisms are always present in large numbers. Among these is Leptothrix buccalis (Fig. 121), which is especially abundant in the crypts of the tonsils and the
Thrush is a disease of the mouth seen most often in children, and characterized by the presence of white patches upon the mucous membrane. It is caused by the thrush fungus, OÏdium albicans. When a bit from one of the patches is pressed out between a slide and cover and examined with a one-sixth objective, the fungus is seen to consist of a network of branching segmented hyphÆ with numerous spores, both within the hyphÆ and in the meshes between them (Fig. 122). The meshes also contain leukocytes, epithelial cells, and granular dÉbris.
Acute pseudomembranous inflammations, which occur chiefly upon the tonsils and nasopharynx, are generally caused by the diphtheria bacillus, but may result from streptococcic infection. In many cases diphtheria
Vincent's angina is a chronic pseudomembranous and ulcerative inflammation of pharynx and tonsils. It is probably caused by two micro-organisms living in symbiosis—one a fusiform bacillus, the other a long spirillum (Fig. 124). They can readily be demonstrated in smears stained with LÖffler's methylene-blue. The bacillus is spindle shaped, more or less pointed at the Tuberculous ulcerations of mouth and pharynx can generally be diagnosed from curetings made after careful cleansing of the surface. The curetings are well rubbed between slide and cover, and the smears thus made are dried, fixed, and stained for tubercle bacilli. Since there is much danger of contamination from tuberculous sputum, the presence of tubercle bacilli is significant only in proportion to the thoroughness with which the ulcer was cleansed. The diagnosis is certain when the bacilli are found within groups of cells which have not been disassociated in making the smears. THE EYE
Staphylococci, pneumococci, and streptococci are probably the most common of the bacteria to be found in nonspecific conjunctivitis and keratitis. The usual cause of acute infectious conjunctivitis, especially in cities, seems to be the Koch-Weeks bacillus. This is a minute, slender rod, which lies within and between the pus-corpuscles (Fig. 125), and is negative to Gram's stain. In smears it cannot be
Early diagnosis of gonorrheal ophthalmia is extremely important, and can be made with certainty only by detection of gonococci in the discharge. They are easily found in smears from untreated cases. After treatment is begun they soon disappear, even though the discharge continues. Pseudomembranous conjunctivitis generally shows either streptococci or diphtheria bacilli. In diagnosing diphtheric conjunctivitis, one must be on his guard against the Various micro-organisms—bacteria, molds, protozoa—have been described in connection with trachoma, but the specific organism of the disease is not definitely known. THE EAR By far the most frequent exciting causes of acute otitis media are the pneumococcus and the streptococcus. The finding of other bacteria in the discharge generally indicates a secondary infection, except in cases complicating infectious diseases, such as typhoid fever, diphtheria, and influenza. Discharges which have continued for some time are practically always contaminated with the staphylococcus. The presence of the streptococcus should be a cause of uneasiness, since it much more frequently leads to mastoid disease and meningitis than does the pneumococcus. The staphylococcus, bacillus of FriedlÄnder, colon bacillus, and Bacillus pyocyaneus may be met in chronic middle-ear disease. In tuberculous disease the tubercle bacillus is present in the discharge, but its detection offers some difficulties. It is rarely easy to find, and precautions must always be taken to exclude the smegma and other acid-fast bacilli (p. 35), which are especially liable to be present in the ear. Rather striking is the tendency of old squamous cells to retain the red stain, and fragments of such cells may mislead the unwary. PARASITIC DISEASES OF THE SKIN Favus, tinea versicolor, and the various forms of ring-worm are caused by members of the fungus group. To demonstrate them, a crust or a hair from the affected area is softened with a few drops of 20 per cent. caustic soda solution, pressed out between a slide and cover, and examined with a one-sixth objective. They consist of a more or less dense network of hyphÆ and numerous round or oval refractive spores. The cuts in standard works upon diseases of the skin will aid in differentiating the members of the group. MILK A large number of analyses of human and cow's milk are averaged by Holt as follows, Jersey milk being excluded because of its excessive fat:
The reaction of human milk is slightly alkaline; of cow's, neutral or slightly acid. The specific gravity of each is about 1.028 to 1.032. Human milk is sterile when secreted, but derives a few bacteria from the lacteal ducts. Cow's milk, as usually sold, contains large numbers of bacteria. Microscopically, human milk is a fairly homogeneous emulsion of fat, and is practically destitute of cellular elements.
Chemic examination of milk is of great value in solving For more accurate work the following methods, applicable to either human or cow's milk, are simple and satisfactory.
It is frequently desirable to detect formalin, which is the most common preservative added to cow's milk. Add a few drops of dilute phenol solution to a few cubic centimeters of the milk, and run the mixture gently upon the surface of some strong sulphuric acid in a test-tube. If formaldehyd be present, a bright-red ring will appear SYPHILITIC MATERIAL
In 1905 Schaudinn and Hoffmann described the occurrence of a very slender, spiral micro-organism in the lesions of syphilis. This they named SpirochÆte pallida, because of its low refractive power and the difficulty with which it takes up staining reagents. Its etiologic
SpirochÆte pallida is an extremely slender, spiral, motile thread, with pointed ends. It varies considerably in length, the average being about 7 µ, or the diameter of a red blood-corpuscle; and it exhibits three to twelve, sometimes more, spiral curves, which are sharp and regular and resemble the curves of a corkscrew (Fig. 129). It is so delicate that it is difficult to see even in well-stained preparations; a high magnification and careful focusing are, therefore, required. Upon ulcerated surfaces it is often mingled with other spiral micro-organisms, which adds to the difficulty of its detection. The most notable of these is SpirochÆte refringens, which is distinguished by being coarser and having fewer curves of wider and less sharp contour (Fig. 130). SpirochÆte pallida is most easily demonstrated in chancres and mucous patches, although the skin lesions—papules, pustules, roseolous areas—often contain large numbers. Tissue-juice from the deeper portions of the lesions is the most favorable material for examination, because the organisms are commonly more abundant than upon ulcerated surfaces and are rarely accompanied by other micro-organisms. After cleansing the surface a superficial incision with a scalpel or sharp needle is made at the edge of a lesion, or the surface is gently scraped away with a curet, and a drop of blood and serum is expressed. The less blood the better, because the Goldhorn's stain gives very good results. It can be purchased ready prepared from E. Leitz, New York. The unfixed smear is covered with the stain for four or five seconds. The excess of stain is poured off, and the preparation introduced slowly, with the film side down, into distilled water. It is held in this position for four or five seconds, and is then washed by shaking about in the water. By this method the SpirochÆte pallida appears of a violet color, which can be changed to bluish black by flooding with Gram's iodin solution for fifteen or twenty seconds. The preparation is then washed, dried, and mounted. SEMEN Absence of spermatozoa is a more common cause of sterility than is generally recognized. In some cases they are present, but lose their motility immediately after ejaculation. Semen must be kept warm until examined. When it must be transported any considerable distance, the method suggested by Boston is convenient. The fresh semen is placed in a small bottle to the neck of which a string is attached. This is then suspended from a button on the trousers so that the bottle rests against the skin of the inguinal region. It may be carried in this way for hours. When ready to examine, place a small quantity upon a warmed slide and apply a cover. The spermatozoa are readily seen with a one-sixth objective (Fig. 53). Normally, they are abundant and in active motion. Detection of semen in stains upon clothing, etc., is
Florence's Reaction.—The suspected material is softened with water, placed upon a slide with a few drops of the reagent, and examined at once with a medium power of the microscope. If the material be semen, there will be found dark-brown crystals (Fig. 131) in the form of rhombic platelets resembling hemin crystals, or of needles often grouped in clusters. These crystals can The reagent consists of iodin, 2.54 gm.; potassium iodid, 1.65 gm.; and distilled water, 30 c.c. APPENDIXI. APPARATUS AND REAGENTSThe apparatus and reagents listed here are sufficient for all the tests described in the text. Those in smaller type are less frequently required. For ordinary routine work a much smaller list will suffice. A. APPARATUS Beakers and flasks, several sizes, preferably of Jena glass. Blood lancet, or some substitute (Fig. 64). Bunsen-burner or alcohol lamp. Buret, 25 c.c. capacity; preferably with Schellbach stripe. Buret and filter-stand combined. Centrifuge—hand, electric, or water-power (Figs. 16 and 17). With the last two a speed indicator is desirable. Radius of arm when in motion should be six and three-fourth inches. Plain and graduated tubes accompany the instrument; milk-tubes (Fig. 128) must be purchased separately. When sedimentation only is desired, the torfuge (Fig. 31) is a cheap and convenient substitute. Cigaret-paper, "Zig-zig" brand, or some similar thin paper. Corks, preferably of rubber, with one and two holes. Cover-glasses, No. 2 thickness—seven-eighth-inch squares are most convenient. Esbach's tube (Fig. 23). Evaporating dish. Filter-paper: ordinary cheap paper for urine filtration; "ashless" quantitative filter-paper for chemic analyses. Glass funnels. Glass rods and tubing of sodium glass: for stirring rods, urinary pipets, etc. Glass slides: the standard 1- by 3-inch size will answer for all work, although a few larger slides will be found convenient; those of medium thickness are preferable. Graduates, cylindric form, several sizes. Granite-ware basin. Hemoglobinometer: see pp. 143 to 147 for descriptions of the different instruments. Hemocytometer: either TÜrk or Zappert ruling is desirable (Figs. 69, 70, and 72). Labels for slides and bottles. Litmus paper, red and blue, Squibb's preferred. Microscope (Fig. 1): should have AbbÉ condenser, 1- and 2-inch eye-pieces, and two-thirds, one-fifth, or long focus one-sixth and one-twelfth inch objectives. A one-half inch eye-piece, a micrometer eye-piece, and an attachable mechanical stage are very useful additions. Petri dish or cleaned photographic plates for sputum examination. Stomach-tube. Test-glass, conic, one side painted half white, half black. Test-tubes, rack, and cleaning brush. Ureometer, Doremus-Hinds' pattern (Fig. 20). Urinometer, preferably Squibb's (Fig. 14).
B. REAGENTS AND STAINS All stains and many reagents are best kept in small dropping bottles. FormulÆ are given in the text. Acid, glacial acetic. Other strengths can be made from this as desired. Acid, hydrochloric, concentrated (contains about 32 per cent. by weight of absolute hydrochloric acid). Other strengths can be made as desired. Acid, nitric, strong, colorless. Acid, nitric, yellow. Can be made from colorless acid by adding a splinter of pine, or allowing to stand in sunlight. Acid, sulphuric, concentrated. Alcohol, ethyl (grain-alcohol). This is ordinarily about 93 to 95 per cent., and other strengths can be made as desired. Aqua ammoniÆ fortior (sp. gr. 0.9). Bromin or Rice's solutions (p. 67), for urea estimation. Diluting fluid for erythrocyte count (p. 154). Diluting fluid for leukocyte count (p. 165). Dimethyl-amido-azobenzol, 0.5 per cent. alcoholic solution. Distilled water. Esbach's reagent (p. 74). Ether, sulphuric. Ferric chlorid: saturated aqueous solution and 10 per cent. aqueous solution. Haines' (or Fehling's) solution (p. 78). Lugol's solution (Liquor Iodi Compositus, U.S.P.). Gram's iodin solution (p. 38) can be made from this by adding fourteen times its volume of water. Obermayer's reagent (p. 64). Phenylhydrazin, pure. Phenol. Phenolphthalein, 1 per cent. alcoholic solution. Purdy's (or Fehling's) solution (p. 80). Robert's reagent (p. 73). Sodium chlorid (table-salt), saturated aqueous solution. Sodium hydroxid (caustic soda), 40 per cent. solution; other strengths can be made from this as desired. Sodium hydroxid, decinormal solution. This is best purchased ready prepared. Sodium nitrite, 0.5 per cent. solution for diazo reaction. Must be freshly prepared. Sulphanilic acid solution for diazo reaction (p. 91). Stains:
Tincture of guaiac, diluted to a light sherry-wine color (keep in a dark-glass bottle). Turpentine, "ozonized" (p. 89).
II. WEIGHTS, MEASURES, ETC., WITH EQUIVALENTS
AVOIRDUPOIS WEIGHT
APOTHECARIES' MEASURE
APOTHECARIES' WEIGHT
TEMPERATURE
To convert Fahrenheit into Centigrade subtract 32 and multiply by 0.555. To convert Centigrade into Fahrenheit multiply by 1.8 and add 32. INDEX Absorptive power of stomach, 233 89 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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