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Ab-do´men (Latin abdo, to conceal). The largest cavity of the body containing the liver, stomach, intestines, etc.; the belly.

Ab-sor´bents (L. ab and sorbeo, to suck up). The vessels which take part in the process of absorption.

Ab-sorp´tion. The process of sucking up fluids by means of an animal membrane.

Ac-com-mo-da´tion of the Eye. The alteration in the shape of the crystalline lens, which accommodates or adjusts the eye for near and remote vision.

Ac´id, Lactic (L. lac, milk). The acid ingredient of sour milk; the gastric juice also contains it.

Al-bu´men, or Albumin (L. albus, white). An animal substance resembling white of egg.

Al-bu´mi-nose (from albumen). A soluble animal substance produced in the stomach by the digestion of the albuminoid substances.

Al-bu´min-oid substances. A class of proximate principles resembling albumen; they may be derived from either the animal or vegetable kingdoms.

Al´i-ment (L. alo, to nourish). That which affords nourishment; food.

Al-i-ment´a-ry Ca-nal (from aliment). A long tube in which the food is digested, or prepared for reception into the system.

An-Æs-thet´ics (Greek, a?, an, without, a?s?es?a, aisthesia, feeling).—Those medicinal agents which prevent the feeling of pain, such as chloroform, laughing-gas, etc.

An-i-mal´cule (L. animal´culum, a small animal). Applied to animals which can only be seen with the aid of the microscope. Animalculum (plural, animalcula) is used with the same meaning.

A-or´ta (Gr. ???t??a?, aorteomai, to be lifted up). The largest artery of the body, and main trunk of all the arteries. It arises from the left ventricle of the heart. The name was first applied to the two large branches of the trachea, which appear to be lifted up by the heart.

A´que-ous Humor (L. aqua, water). A few drops of watery colorless fluid occupying the space between the cornea and crystalline lens.

A-rach´noid Mem´brane (Gr. ?????e, arachne, a cobweb, and e?d??, eidos, like). An extremely thin covering of the brain and spinal cord. It lies between the dura mater and the pia mater.

Ar´bor Vi´tÆ (L.). Literally, "the tree of life;" a name given to the peculiar appearance presented by a section of the cerebellum.

Ar´ter-y (Gr. ???, aer, air, and t??e??, terein, to contain). A vessel by which blood is conveyed away from the heart. It was supposed by the ancients to contain air; hence the name.

Ar-tic-u-la´tion (L. articulo, to form a joint). The more or less movable union of bones, etc.; a joint.

A-ryt´e-noid Car´ti-la-ges (Gr. ???ta??a, arutaina, a pitcher). Two small cartilages of the larynx, resembling the mouth of a pitcher.

As-sim-i-la´tion (L. ad, to, and similis, like). The conversion of food into living tissue.

Au-di´tion (L. audio, to hear). The act of hearing sounds.

Au´di-to-ry Nerve. One of the cranial nerves; it is the special nerve of hearing.

Au´ri-cle (L. auris, the ear). A cavity of the heart.

Bar´i-tone (Gr. a???, barus, heavy, and t????, tonos, tone). A variety of male voice between the bass and tenor.

Bel-la-don´na (It. beautiful lady). A vegetable narcotic poison. It has the property of enlarging the pupil, and thus increasing the brilliancy of the eye; so called from its use by Italian ladies.

Bi-cus´pid (L. bi, two, and cuspis, prominence). The name of the fourth and fifth teeth on each side of the jaw; possessing two prominences.

Bile. The gall, or peculiar secretion of the liver; a viscid, yellowish fluid, and very bitter to the taste.

Bronch´i (Gr. ??????, bronkos, the windpipe). The two first divisions or branches of the trachea; one enters each lung.

Bronch´i-al Tubes. The smaller branches of the trachea within the substance of the lungs, terminating in the air-cells.

Bronch-i´tis (from bronchia, and itis, a suffix signifying inflammation). An inflammation of the larger bronchial tubes; a "cold" affecting the lungs.

Cal-ca´re-ous (L. calx, lime). Containing lime.

Ca-nal´ (L.). In the body, any tube or passage.

Ca-nine´ (L. canis, a dog). Name given to the third tooth on each side of the jaw; in the upper jaw it is also known as the eye-tooth: pointed like the tusks of a dog.

Cap´il-la-ry (L. capil´lus, a hair, capilla´ris hair-like). The name of the extremely minute blood-vessels which connect the arteries with the veins.

Car´bon Diox-ide (CO₂). Chemical name for carbonic acid gas.

Car-bon´ic A-cid. The gas which is present in the air expired from the lungs; a waste product of the animal kingdom, and a food of the vegetable kingdom.

Car´di-ac (Gr. ?a?d?a, cardia, the heart). The cardiac orifice of the stomach is the upper one, and is near the heart; hence its name.

Car-niv´o-rous (L. ca´ro, flesh, and vo´ro, to devour). Subsisting upon flesh.

Ca-rot´id Ar-te-ry. The large artery of the neck, supplying the head and brain.

Car´ti-lage. A solid but flexible material, forming a part of the joints, air-passages, nostrils, etc.; gristle.

Ca´se-ine (L. ca´seus, cheese). The albuminoid substance of milk; it forms the basis of cheese.

Cer-e-bel´lum (diminutive for cer´ebrum, the brain). The little brain, situated beneath the posterior third of the cerebrum.

Cer´e-brum (L.). The brain proper, occupying the entire upper portion of the skull. It is nearly divided into two equal parts, called "hemispheres," by a cleft extending from before backward.

Cho´roid (Gr. ??????, chorion, a membrane or covering). The middle tunic or coat of the eyeball.

Chyle (Gr. ?????, chulos, juice). The milk-like fluid formed by the digestion of fatty articles of food in the intestines.

Chyme (Gr. ????, chumos, juice). The pulpy liquid formed by digestion within the stomach.

Cil´i-a (pl. of cil´i-um, an eyelash). Minute, vibratile, hair-like processes found upon the cells of the air-passages, and other parts that are habitually moist.

Cir-cu-la´tion (L. cir´culus, a ring). The circuit, or course of the blood through the blood-vessels of the body, from the heart to the arteries, through the capillaries into the veins, and from the veins back to the heart.

Co-ag-u-la´tion (L. coag´ulo, to curdle). Applied to the process by which the blood clots or solidifies.

Coch´le-a (L. coch´lea, a snail-shell). The spiral cavity of the internal ear.

Conch´a (Gr. ?????, konche, a mussel-shell). The external shell-shaped portion of the external ear.

Con-junc-ti´va (L. con and jun´go, to join together). A thin layer of mucous membrane which lines the eyelids and covers the front of the eyeball; thus joining the latter to the lids.

Con-trac-til´i-ty (L. con and tra´ho, to draw together). The property of a muscle which enables it to contract, or draw its extremities closer together.

Con-vo-lu´tions (L. con and vol´vo, to roll together). The tortuous foldings of the external surface of the brain.

Con-vul´sion (L. convel´lo, to pull together). A more or less violent agitation of the limbs or body.

Cor´ne-a (L. cor´nu, a horn). The transparent, horn-like substance which covers the anterior fifth of the eyeball.

Cor´pus-cles, Blood (L. dim. of cor´pus, a body). The small biconcave disks which give to the blood its red color; the white corpuscles are globular and larger.

Cos-met´ic (Gr. ??s??, kosmeo, to adorn). Beautifying; applied to articles which are supposed to increase the beauty of the skin, etc.

Cra´ni-al (L. cra´nium, the skull). Pertaining to the skull. The nerves which arise from the brain are called cranial nerves.

Cri´coid (Gr. ??????, kri´kos, a ring). A cartilage of the larynx, resembling a seal-ring in shape.

Crys´tal-line Lens (L. crystal´lum, a crystal). One of the so-called humors of the eye; a double convex body situated in the front part of the eyeball.

Cu´ti-cle (L. dim. of cu´tis, the skin). The scarf-skin; also called the epider´mis.

Cu´tis (Gr. s??t??, skutos, a skin or hide). The true skin, lying beneath the cuticle; also called the der´ma.

De-cus-sa´tion (L. decus´sis, the Roman numeral ten, X). A reciprocal crossing of fibres from side to side.

Di´a-phragm (Gr. d?af??ss?, diaphrasso, to divide by a partition). A large, thin muscle which separates the cavity of the chest from the abdomen; a muscle of respiration.

Dif-fus´ion of Gases. The power of gases to become intimately mingled, without reference to the force of gravity.

Duct (L. du´co, to lead). A narrow tube; the thoracic duct is the main trunk of the absorbent vessels.

Du-o-de´num (L. duode´ni, twelve). The first division of the small intestines, about twelve fingers-breadth long.

Du´ra Ma´ter (L.). Literally, the hard mother; the tough membrane which envelops the brain.

Dys-pep´si-a (Gr. d??, dus, difficult, and p?pt?, pep´to, to digest). Difficult or painful digestion; a disordered condition of the stomach.

E-mul´sion (L. emul´geo, to milk). Oil in a finely divided state suspended in water.

En-am´el (Fr. email). The dense material which covers the crown of the tooth.

En´er-gy, Specific, of a Nerve. When a nerve of special sense is excited, whatever be the cause, the sensation experienced is that peculiar to the nerve; this is said to be the law of the specific energy of the nerves.

Ep-i-glot´tis (Gr. ?p?, epi, upon, and ???tt??, glottis, the entrance to the windpipe). A leaf-shaped piece of cartilage which covers the top of the larynx during the act of swallowing.

Ex-cre´tion (L. excer´no, to separate). The separation from the blood of the waste particles of the body; also the materials excreted.

Ex-pi-ra´tion (L. expi´ro, to breathe out). The act of forcing air out of the lungs.

Ex-ten´sion (L. ex, out, and ten´do, to stretch). The act of restoring a limb, etc., to its natural position after it has been flexed, or bent; the opposite of Flexion.

Fe-nes´tra (L.). Literally, a window; the opening between the middle and internal ear.

Fi´brin (L. fi´bra, a fibre). An albuminoid substance found in the blood; in coagulating it assumes a fibrous form.

Flex´ion (L. flec´to, to bend). The act of bending a limb, etc.

Fol´li-cle (L. dim. of fol´lis, a bag). A little pouch or depression in a membrane; it has generally a secretory function.

Fun´gous Growths (L. fun´gus, a mushroom). A low grade of vegetable life.

Gan´gli-on (Gr. ?a??????, ganglion, a knot). A knot-like swelling in the course of a nerve; a smaller nerve-centre.

Gas´tric (Gr. ?ast??, gaster, stomach). Pertaining to the stomach.

Gland (L. glans, an acorn). An organ consisting of follicles and ducts, with numerous blood-vessels interwoven; it separates some particular fluid from the blood.

Glos´so-phar-yn-ge´al Nerve (Gr. ???ssa, glossa, the tongue, and f?????, pharunx, the throat). The nerve of taste supplying the posterior third of the tongue; it also supplies the throat.

Glu´ten (L.). Literally, glue: the glutinous albuminoid ingredient of wheat.

Gran´ule (L. dim. of gra´num, a grain). A little grain; a microscopic object.

Gus-ta´tion (L. gus´to, to taste) The sense of taste.

Gus´ta-to-ry Nerve. The nerve of taste supplying the front part of the tongue; a branch of the "fifth" pair.

HÆm´or-rhage (Gr. ??a, hai´ma, blood, and ??????, regnumi, to burst). Bleeding, or the loss of blood.

Hem-i-ple´gia (Gr. ??s??, hemisus, half, and p??ss?, plesso, to strike). Paralysis, or loss of power, affecting one side of the body.

Hem´i-spheres (Gr. sfa??a, sphaira, a sphere). Half a sphere, the lateral halves of the cerebrum, or brain proper.

He-pat´ic (Gr. ?pa?, hepar, the liver). Pertaining to the liver.

Her-biv´o-rous (L. her´ba, an herb, and vo´ro to devour). Applied to animals that subsist upon vegetable food.

Hu´mor (L.). Moisture: the humors are transparent contents of the eyeball.

Hy-dro-pho´bi-a (Gr. ?d??, hudor, water, and f???, phobeo, to fear). A disease caused by the bite of a rabid dog or other animal. In a person affected with it, convulsions are occasioned by the sight of a glittering object, like water, by the sound of running water, and by almost any external impression.

Hy´gi-ene (Gr. ???e?a, huygieia, health). The art of preserving health and preventing disease.

Hy´per-o-pi-a. Abbreviated from Hy´per-met-ro´pi-a (Gr. ?p??, huper, beyond, ?t???, metron, the measure, and ??, ops, the eye). A defect of vision dependent upon a too short eyeball; so called because the rays of light are brought to a focus at a point behind the retina; the true "far sight."

In-ci´sor (L. inci´do, to cut). Applied to the four front teeth of both jaws, which have sharp cutting edges.

In´cus (L). An anvil; the name of one of the bones of the middle ear.

In-sal-i-va´tion (L. in, and sali´va, the fluid of the mouth). The mingling of the saliva with the food during the act of chewing.

In-spi-ra´tion (L. in, and spi´ro, spira´tum, to breathe). The act of drawing in the breath.

In-teg´u-ment (L. in, and te´go, to cover). The skin, or outer covering of the body.

In-tes´tine (L. in´tus, within). The part of the alimentary canal which is continuous with the lower end of the stomach; also called the intestines, or the bowels.

I´ris (L. i´ris, the rainbow). The thin muscular ring which lies between the cornea and crystalline lens, and which gives the eye its brown, blue, or other color.

Ju´gu-lar (L. ju´gulum, the throat). The name of the large veins which run along the front of the neck.

Lab´y-rinth (Gr. ?a???????, laburin´thos, a building with many winding passages). The very tortuous cavity of the inner ear, comprising the vestibule, semicircular canals, and the cochlea.

Lach´ry-mal Apparatus (L. lach´ryma, a tear). The organs for forming and conveying away the tears.

Lac´te-als (L. lac, lac´tis, milk). The absorbent vessels of the small intestines; during digestion they are filled with chyle, which has a milky appearance.

La-ryn´go-scope (Gr. ??????, larunx, the larynx, and s??pe?, skopeo, to look at). The instrument by which the larynx may be examined in the living subject.

Lar´ynx (Gr.). The cartilaginous tube situated at the top of the windpipe, or trachea; the organ of the voice.

Lens (L.). Literally, a lentil; a piece of transparent glass or other substance so shaped as either to converge or disperse the rays of light.

Lig´a-ment (L. li´go, to bind). A strong, fibrous material binding bones or other solid parts together; it is especially necessary to give strength to joints.

Lig´a-ture. A thread of silk or other material used in tying around an artery.

Lymph (L. lym´pha, spring-water). The colorless, watery fluid conveyed by the lymphatic vessels.

Lym-phat´ic Vessels. A system of absorbent vessels.

Mal´le-us (L.). Literally, the mallet; one of the small bones of the middle ear.

Mar´row. The soft, fatty substance contained in the central cavities of the bones: the spinal marrow, however, is composed of nervous tissue.

Mas-ti-ca´tion (L. mas´tico, to chew). The act of cutting and grinding the food to pieces by means of the teeth.

Me-dul´la Ob-lon-ga´ta. The "oblong marrow," or nervous cord, which is continuous with the spinal cord within the skull.

Mem-bra´na Tym´pan-i (L.). Literally, the membrane of the drum; a delicate partition separating the outer from the middle ear; it is sometimes incorrectly called the drum of the ear.

Mem´brane. A thin layer of tissue serving to cover some part of the body.

Mi´cro-scope (Gr. ?????, mikros, small, and s??p??, skopeo, to look at). An optical instrument which assists in the examination of minute objects.

Mo´lar (L. mo´la, a mill). The name applied to the three back teeth of each side of the jaw; the grinders, or mill-like teeth.

Mo´tor (L. mo´veo, mo´tum, to move). Causing motion; the name of those nerves which conduct to the muscles the stimulus which causes them to contract.

Mu´cous Membrane. The thin layer of tissue which covers those internal cavities or passages which communicate with the external air.

Mu´cus. The glairy fluid which is secreted by mucous membranes, and which serves to keep them in a moist condition.

My-o´pi-a (Gr. ??, muo, to contract, and ??, ops, the eye). A defect of vision dependent upon an eyeball that is too long, rendering distant objects indistinct; near-sight.

Na´sal (L. na´sus, the nose). Pertaining to the nose; the nasal cavities contain the distribution of the special nerve of smell.

Nerve (Gr. ?e????, neuron, a cord or string). A glistening, white cord of cylindrical shape, connecting the brain or spinal cord with some other organ of the body.

Nerve Cell. A minute, round and ashen-gray cell found in the brain and other nervous centres.

Nerve Fi´bre. An exceedingly slender thread of nervous tissue found in the various nervous organs, but especially in the nerves; it is of a white color.

Nu-tri´tion (L. nu´trio, to nourish). The processes by which the nourishment of the body is accomplished.

Œ-soph´a-gus (Gr.). Literally, that which carries food. The tube leading from the throat to the stomach; the gullet.

O-le-ag´i-nous (L. o´leum, oil). Of the nature of oil: applied to an important group of food-principles—the fats.

Ol-fac´to-ry (L. olfa´cio, to smell). Pertaining to the sense of smell.

Oph-thal´mo-scope (Gr. ?f?a???, ophthalmos, the eye, and s??p??, skopeo, to look at). An instrument devised for examining the interior of the globe of the eye.

Op´tic (Gr. ?pt?, opto, to see). Pertaining to the sense of sight.

Or´bit (L. or´bis, the socket). The bony socket or cavity in which the eyeball is situated.

Os´mose (Gr. ?s??, osmos, a thrusting or impulsion). The process by which liquids are impelled through a moist membrane.

Os´se-ous (L. os, a bone). Consisting of, or resembling bone.

Pal´ate (L. pala´tum, the palate). The roof of the mouth, consisting of the hard and soft palate.

Pal´mar. Relating to the palm of the hand.

Pan´cre-as (Gr. p??, pa?t??, pas, pantos, all, and ???a?, kreas, flesh). A long, flat gland situated near the stomach; in the lower animals the analogous organ is called the sweet-bread.

Pa-pil´lÆ (L. papil´la). The minute prominences in which terminate the ultimate fibres of the nerves of touch and taste.

Pa-ral´y-sis. A disease of the nervous system marked by the loss of sensation, or voluntary motion, or both; palsy.

Par-a-ple´gi-a (Gr. pa?ap??ss?, paraplesso, to strike amiss). A form of paralysis affecting the lower half of the body.

Pa-tel´la (L. dim. of pat´ina, a pan). The knee-pan; a small bone.

Pel´vis (L.). Literally a basin; the bony cavity at the lower part of the trunk.

Pep´sin (Gr. p?pt?, pepto, to digest). The organic principle of the gastric juice.

Per-i-stal´tic Move´ments (Gr. pe??st????, peristello, to contract). The slow, wave-like movements of the stomach and intestines.

Per-i-to-ne´um (Gr. pe??te???, periteino, to stretch around). The investing membrane of the stomach, intestines, and other abdominal organs.

Per-spi-ra´tion (L. perspi´ro, to breathe through). The sweat, or watery exhalation of the skin; when visible, it is called sensible perspiration, when invisible, it is called insensible perspiration.

Pe´trous (Gr. p?t?a, petra, a rock). The name of the hard portion of the temporal bone, in which is situated the drum of the ear and labyrinth.

Phar´ynx (Gr. f?????, pharunx, the throat). The cavity between the back of the mouth and gullet.

Phys-i-ol´o-gy (Gr. f?s??, phusis, nature, and ?????, logos, a discourse). The science of the functions of living, organized beings.

Pi´a Ma´ter (L.). Literally, the tender mother; the innermost of the three coverings of the brain. It is thin and delicate; hence the name.

Pleu´ra (Gr. p?e???, a rib). A membrane covering the lung and lining the chest. There is one for each lung.

Pleu´ri-sy. An inflammation affecting the pleura.

Pneu-mo-gas´tric (Gr. p?e???, pneumon, the lungs, and ?ast??, gaster, the stomach). The name of a nerve distributed to the lungs and stomach; it is the principal nerve of respiration.

Pneu-mo´nia (Gr.). An inflammation affecting the air-cells of the lungs.

Pres-by-o´pi-a (Gr. p??s??, presbus, old, and ??, ops, the eye). A defect of the accommodation of the eye, caused by the hardening of the crystalline lens; the "far-sight" of adults and aged persons.

Proc´ess (L. proce´do, proces´sus, to proceed, to go forth). Any projection from a surface. Also, a method of performance; a procedure.

Pty´a-lin (Gr. pt?a???, ptualon, saliva). The peculiar organic ingredient of the saliva.

Pul´mo-na-ry (L. pul´mo, pulmo´nis, the lungs). Pertaining to the lungs.

Pulse (L. pel´lo, pul´sum, to beat). The striking of an artery against the finger, occasioned by the contraction of the heart, commonly felt at the wrist.

Pu´pil (L. pupil´la). The central, round opening in the iris, through which light passes into the depths of the eye.

Py-lo´rus (Gr. p??????, puloros, a gate-keeper). The lower opening of the stomach, at the beginning of the small intestine.

Re´flex Action. An involuntary action of the nervous system, by which an external impression conducted by a sensory nerve is reflected, or converted into a motor impulse.

Res-pi-ra´tion (L. res´piro, to breathe frequently). The function of breathing, comprising two acts: inspiration, or breathing in, and expiration, or breathing out.

Ret´i-na (L. re´te, a net). The innermost of the three tunics or coats of the eyeball, being an expansion of the optic nerve.

Sac´cha-rine (L. sac´charum, sugar). Of the nature of sugar; applied to the important group of food substances which embraces the different varieties of sugar, starch, and gum.

Sa-li´va (L.). The moisture or fluids of the mouth, secreted by the salivary glands, etc.

Scle-rot´ic (Gr. s??????, skleros, hard). The tough, fibrous outer tunic of the eyeball.

Se-ba´ceous (L. sebum, fat). Resembling fat, the name of the oily secretion by which the skin is kept flexible and soft.

Se-cre´tion (L. secer´no, secre´tum, to separate). The process of separating from the blood some essential important fluid; which fluid is also called a secretion.

Sem-i-cir´cu-lar Canals. A portion of the internal ear.

Sen-sa´tion. The perception of an external impression by the nervous system; a function of the brain.

Sen-si-bil´i-ty, General. The power possessed by nearly all parts of the human body of recognizing the presence of foreign objects that come in contact with them.

Se´rum (L.). The watery constituent of the blood, which separates from the clot during the process of coagulation.

Skel´e-ton (Gr.). The bony framework of an animal, the different parts of which are maintained in their proper relative positions.

Spec´tro-scope (from spec´trum and s??p??, scopeo, to examine the spectrum). An instrument employed in the examination of the spectrum of the sun or any other luminous body.

Sphyg´mo-graph (Gr. sf????, sphugmos, the pulse, and ???f?, grapho, to write). An ingenious instrument by means of which the pulse is delineated upon paper.

Sta´pes (L.). Literally, a stirrup; one of the small bones of the tympanum, or middle ear, resembling somewhat a stirrup in shape.

Sym-pa-thet´ic system of Nerves. A double chain of nervous ganglia, connected together by numerous small nerves, situated chiefly in front of and on each side of the spinal column.

Syn-o´vi-a (Gr. s??, sun, and ???, oon, resembling an egg). The lubricating fluid of joints, so called because it resembles the white of egg.

Sys´to-le (Gr. s?st????, sustello, to contract). The contraction of the heart, by which the blood is expelled from that organ.

Tac´tile (L. tac´tus, touch). Relating to the sense of touch.

Tem´po-ral (L. tem´pus, time, and tem´pora, the temples). Pertaining to the temples; the name of an artery: so called, because the hair begins to turn white with age in that portion of the scalp.

Ten´don (L. ten´do, to stretch). The white, fibrous cord or band by which a muscle is attached to a bone; a sinew.

Tet´a-nus (Gr. te???, teino, to stretch). A disease marked by persistent contractions of all or some of the voluntary muscles; those of the jaw are sometimes solely affected: the disorder is then termed locked-jaw.

Tho´rax (Gr. ???a?, thorax, a breastplate). The upper cavity of the trunk of the body, containing the lungs, heart, etc.; the chest.

Thy´roid (Gr. ???e??, thureos, a shield). The largest of the cartilages of the larynx; its angular projection in the front of the neck is called "Adam's apple."

Tra´che-a (Gr. t?a???, trachus, rough). The windpipe, or the largest of the air-passages; composed in part of cartilaginous rings, which render its surface rough and uneven.

Trans-fu´sion (L. transfun´do, to pour from one vessel to another). The operation of injecting blood taken from one person into the veins of another; other fluids than blood are sometimes used.

Trich-i´na Spi-ra´lis. (L.) A minute species of parasite or worm, which infests the flesh of the hog, and which may be introduced into the human system by eating pork not thoroughly cooked.

Tym´pa-num (Gr. t?pa???, tumpanon, a drum). The cavity of the middle ear, resembling a drum in being closed by two membranes, and in having communication with the atmosphere.

U´vu-la (L. uva, a grape). The small pendulous body attached to the back part of the palate.

Vas´cu-lar (L. vas´culum, a little vessel). Pertaining to, or containing blood-vessels.

Ve´nous (L. ve´na, a vein). Pertaining to, or contained within a vein.

Ven-ti-la´tion. The introduction of fresh air into a room or building, in such a manner as to keep the air within it in a pure condition.

Ven-tril´o-quism (L. ven´ter, the belly, and lo´quor, to speak). A modification of natural speech by which the voice is made to appear to come from a distance. The ancients supposed that the voice was formed in the belly; hence the name.

Ven´tri-cles of the heart. The two largest cavities of the heart, situated at its apex or point.

Ver´te-bral Column (L. ver´tebra, a joint). The back-bone, consisting of twenty-four separate bones, called vertebrÆ, firmly jointed together; also called the spinal column and spine.

Ves´ti-bule. A portion of the internal ear, communicating with the semicircular canals and the cochlea; so called from its fancied resemblance to the vestibule or porch of a house.

Vil´li (L. vil´lus, the nap of cloth). Minute thread-like projections found upon the internal surface of the small intestine, giving it a velvety appearance.

Vit´re-ous (L. vi´trum, glass). Having the appearance of glass; applied to the humor occupying the largest part of the cavity of the eyeball.

Viv-i-sec´tion (L. vi´vus, alive, and se´co, to cut). The practice of operating upon living animals, for the purpose of studying some physiological process.

Vocal Cords. Two elastic bands or ridges situated in the larynx; they are the essential parts of the organs of the voice.