Closely allied to the discovery that sunlight and fresh air are fatal to the microÖrganisms of tuberculosis came the consoling fact that these bacilli, though most horribly ubiquitous and apparently infesting both the heavens above and the earth beneath, had neither wings nor legs, and were absolutely incapable of propelling themselves a fraction of an inch. They do not move—they have to be carried. More than this, like all other disease-germs, while incredibly tiny and infinitesimal, they have a definite weight of their own, and are subject to the law of gravity. They do not flit about hither and thither in the atmosphere, thistledown fashion, but rapidly fall to the floor of whatever room or receptacle they may be thrown in. And the problem of their transference is not that of direct carrying from one victim to the next, but the intermediate one of infected materials, such as are usually associated with visible dust or dirt. In short, keep dust or dirt from the floor, out of our food, away from our fingers or clothing or anything that can be brought to or near the mouth, and you will practically have abolished the possibility of the transference of tuberculosis. The consumptive himself is not a direct source of danger. It is only his filthy or unsanitary surroundings. Put a consumptive, who is careful of his sputum and cleanly in his habits, in a well-lighted, well-ventilated room, or, better still, out of doors, and there will be exceedingly little danger of any other member of his family or of those in the house with him contracting the disease. Wherever there is dirt or dust there is danger, and there almost only. Thorough and effective house-reform—not merely in tenements, alas! but in myriads of private houses as well—would abolish two-thirds of the spread of tuberculosis.

It is not necessary to isolate every consumptive in order to stop the spread of the disease. All that is requisite is to prevent the bacilli in his sputum from reaching the floor or the walls, to have both the latter well lighted and aired, and, if possible, exposed to direct sunlight at some time during the day, and to see that dust from the floor is not raised in clouds by dry sweeping so as to be inhaled into the lungs or settle upon food, fingers, or clothing, and that children be not allowed to play upon such floors as may be even possibly contaminated. These precautions, combined with the five-to-one resisting power of the healthy human organism, will render the risk of transmission of the disease an exceedingly small one. To what infinitesimal proportions this risk can be reduced by intelligent and strict sanitation is illustrated by the fact, already alluded to, of the almost complete germ-freeness of the dust from walls and floors of sanitorium cottages, and by the even more convincing and conclusive practical result, that scarcely a single case is on record of the transmission of this disease to a nurse, a physician, or a servant, or other employee in an institution for its cure.

There is absolutely no rational basis for this panic-stricken dread of an intelligent, cleanly consumptive, or for the cruel tendency to make him an outcast and raise the cry of the leper against him: "Unclean! Unclean!"

It cannot be too strongly emphasized that consumption is transmitted by way of the floor; and if this relay-station be kept sterile there is little danger of its transmission by other means.

Practically all that is needed to break this link is the absolute suppression of what is universally and overwhelmingly regarded as not merely an unsanitary and indecent, but a filthy, vulgar, and disgusting habit—promiscuous expectoration. There is nothing new or unnatural in this repression, this tabu on expectoration. In fact, we are already provided with an instinct to back it. In every race, in every age, in every grade of civilization, the human saliva has been regarded as the most disgusting, the most dangerous and repulsive of substances, and the act of spitting as the last and deepest sign of contempt and hatred; and if directed toward an individual, the deadliest and most unbearable insult, which can be wiped out only by blood. Primitive literature and legend are full of stories of the poisonousness of human saliva and the deadliness of the human bite. It was the "bugs" in it that did it. It is most interesting to see how science has finally, thousands of years afterward, shown the substantial basis of, and gone far to justify, this instinctive horror and loathing.

Not merely are the fluids of the human mouth liable to contain the tubercle bacillus, and that of diphtheria, of pneumonia, and half a dozen other definite disorders, but they are in perfectly healthy individuals, especially where the teeth are in poor condition, simply swarming with millions of bacteria of every sort, some of them harmless, others capable of setting up various forms of suppuration and septic inflammation if introduced into a wound, or even if taken into the stomach. Even if there were no such disease as tuberculosis a campaign to stamp out promiscuous expectoration would be well worth all it cost.

Of course, as a counsel of perfection, the ideal procedure would be promptly to remove each consumptive, as soon as discovered, from his house and place him in a public sanatorium, provided by the state, for the sake of removing him from the conditions which have produced his disease, of placing him under those conditions which alone can offer a hopeful prospect of cure, and of preventing the further infection of his surroundings. The only valid objections to such a plan are those of the expense, which, of course, would be very great. It would be not merely best, but kindest, for the consumptive himself, for his immediate family, and for the community. And enormous as the expense would be, when we have become properly aroused and awake to the huge and almost incredible burden which this disease, with its one hundred and fifty thousand deaths a year, is now imposing upon the United States,—five times as great as that of war or standing army in the most military-mad state in Christendom,—the community will ultimately assume this expense. So long, however, as our motto inclines to remain, "Millions for cure, but not one cent for prevention," we shall dodge this issue.

There can be no question but that each state and each municipality of more than ten thousand inhabitants ought to provide an open-air camp or colony of sufficient capacity to receive all those who are willing to take the cure but unable to meet the expense of a private institution; and, also, some institution of adequate size, to which could be sent, by process of law, all those consumptives who, either through perversity, or the weakness and wretchedness due to their disease, or the apathy of approaching dissolution, fail or are unable to take proper precautions.

When we remember that the careful investigations of the various dispensaries for the treatment of tuberculosis in our larger cities, New York, Boston, Cleveland, report that on an average twenty to thirty per cent of all children living in the same room or apartment with a consumptive member of their family are found to show some form of tuberculosis, it will be seen how well worth while, from every point of view, this provision for the removal and sanatorium treatment of the poorer class of these unfortunates would be. These dispensaries now have, as a most important part of their campaign against the disease, one or more visiting nurses, who, whenever a patient with tuberculosis is brought into the dispensary, visit him in his home, show him how to ventilate and light his rooms as well as may be, give practical demonstrations of the methods of preventing the spread of the disease, advise him as to his food, and see that he is supplied with adequate amounts of milk and eggs, and, finally, round up all the children of the family and any adults who are in a suspicious condition of health, and bring them to the dispensary for examination. Distressing as are these findings, reaching in some cases as high as fifty and sixty per cent of the children, they have already saved hundreds of children, and prevented hundreds of others from growing up crippled or handicapped.

It must be remembered that the tubercle bacillus causes not merely disease of the lungs in children but also a large majority of the crippling diseases of the bones, joints, and spine, together with the whole group of strumous or scrofulous disorders, and a large group of intestinal diseases and of brain lesions, resulting in convulsions, paralysis, hydrocephalus, and death. The battle-ground of the future against tuberculosis is the home.

We speak of the churchyard as "haunted," and we recoil in horror from the leper-house or the cholera-camp. Yet the deadliest known hotbed of horrors, the spawning ground of more deaths than cholera, smallpox, yellow fever, and the bubonic plague combined, is the dirty floor of the dark, unventilated living-room, whether in city tenement or village cottage, where children crawl and their elders spit.

It is scarcely to the credit of our species that for convincing, actual demonstrations of what can be done toward stamping out tuberculosis, by measures directed against the bacillus alone, we are obliged to turn to the lower animals. By a humiliating paradox we are never quite able to put ourselves under those conditions which we know to be ideal from a sanitary point of view. There are too many prejudices, too many vested interests, too many considerations of expense to be reckoned with. But with the lower animals that come under our care we have a clear field, free from obstruction by either our own prejudices or those of others. In this realm the stamping out of tuberculosis is not merely a rosy dream of the future but an accomplished fact, in some quarters even an old story. Two illustrations will suffice, one among domestic animals, the other among wild animals in captivity. The first is among pure-bred dairy cattle, the pedigreed Jerseys and Holsteins. No sooner did the discovery of the bacillus provide us with a means of identification, than the well-known "perlsucht" of the Germans, or "grapes" of the English veterinarians—both names being derived from the curious rounded masses or nodules of exudate found in the pleural cavity and the peritoneum (around the lungs and the bowels), and supposed to resemble pearls and grapes respectively—were identified as tuberculosis, and cows were found very widely infected with it. This unfortunately still remains the case with the large mass of dairy cattle. But certain of the more intelligent breeders owning valuable cattle proceeded to take steps to protect them.

The first step was to test their cows with tuberculin, promptly weeding out and isolating all those that reacted to the disease. It was at first thought necessary to slaughter all these at once. But it was later found that, if they were completely isolated and prevented from communicating the disease to others, this extreme measure was necessary only with those extensively diseased. The others could be kept alive, and if their calves were promptly removed as soon as born, and fed only upon sterilized or perfectly healthy milk, they would be free from the disease. And thus the breeding-life of a particularly valuable and high-bred animal might be prolonged for a number of years. They must, however, be kept in separate buildings and fields, and preferably upon a separate farm from the rest of the herd.

Those cows found healthy were given the best of care, including a marked diminution of the amount of housing or confinement in barns, and were again tested at intervals of six months, several times, to weed out any others which might still have the infection in their systems. In a short time all signs of the disease disappeared, and no other cases developed in these herds unless fresh infection was introduced from without. To guard against this, each farm established a quarantine station, where all new-bought animals, after having been tested with tuberculin and shown to be free from reaction, are kept for a period of at least a year, for careful observation and study, before being allowed to mix with the rest of the herd. It is now a common requirement among intelligent breeders of pedigreed cattle to demand, as a formal condition of sale, their submission to the tuberculin test, or the certificate of a competent veterinarian that the animal has been so tested without reacting. Protected herds have now been in existence under these conditions, notably in Denmark, where the method was first reduced to a system under the able leadership of Professor Bang, of Copenhagen, for ten years with scarcely a single case of tuberculosis developing. Only a fraction of one per cent of calves from the most diseased mothers are born diseased.

Not only is the method spreading rapidly among the more intelligent class of breeders, but many progressive countries of Europe and states of our Union require the passing of the tuberculin test as a requisite to the admission within their borders of cattle intended for breeding purposes. So that, while the problem is still an enormous one, it is now confidently believed that complete eradication of bovine tuberculosis is only a question of time.

The other instance furnishes a much more crucial test, as it is carried out upon wild animals under the unfavorable conditions of captivity in a strange climate, like our slum-dwellers from sunny Italy, and comes home to us more closely in many respects, inasmuch as it is concerned with our nearest animal relatives on the biological side—monkeys and apes, in zoÖlogical gardens.

Tuberculosis is a perfectly frightful scourge to these unfortunate captives, causing not infrequently thirty, fifty, and even sixty per cent of the deaths. This, however, is only in keeping with their frightful general mortality. The collection of monkeys in the London Zoo, for instance, some fifteen years ago, was absolutely exterminated by disease and started over afresh every three years, a death-rate of thirty-five per cent per annum as compared with our human rate of about two per cent per annum. Here, it would seem, was an instance where there was little need to call in the bacillus. Brought from a tropical climate to one of raw, damp fog and smoke, from the freedom of the air-roads through the tree-tops to the confinement of dismal and often dirty cages in a stuffy, overheated house, condemned to a diet which at best could be but a feeble and far-distant imitation of their natural food, it seemed little wonder that they "jes' natcherly pined away an' died."

But let the results speak. A thorough system of quarantine was enforced, beginning with one of the Vienna gardens, and finally reaching one of its most brilliant and successful exemplifications in our own New York ZoÖlogical Gardens in the Bronx. All animals purchased or donated were tested with tuberculin, and those that reacted were either painlessly destroyed or disposed of. Those which appeared to be immune were kept in a thoroughly healthy, sanitary quarantine station for six months or a year, and again tested by tuberculin before being introduced into the cages. The original stock of monkeys was treated in the same manner or else destroyed completely, and the houses and cages thoroughly cleaned and sterilized or new ones constructed. Keepers employed in the monkey-house were carefully tested for signs of tuberculosis, and rejected or excluded if any appeared. Signs were posted forbidding any expectoration or feeding of the animals (which latter is often done with nuts or fruit which had been cracked or bitten before being handed to the monkeys) by the general public, and these rules were strictly enforced.

At the same time the houses were thoroughly ventilated and exposed to sunlight as much as possible, and the animals were turned out into open air cages whenever the weather would possibly permit. As a result the mortality from tuberculosis promptly sank from thirty per cent to five or six per cent. In our Bronx Zoo, for instance, it has become decidedly rare as a cause of death in monkeys, no case having occurred in the monkey-house for eighteen months past. What is even more gratifying, the general mortality declined also, though in less proportion, so that, instead of losing twenty-five to thirty per cent of the animals in the house every year, a mortality of ten to fifteen per cent is now considered large.

And to think that we might achieve the same results in our own species if we would only treat ourselves as well as we do our monkey captives! To "make a monkey of one's self" might have its advantages from a sanitary point of view.

"But this method," some one will remind us, "would silence only a part of the enemy's infection batteries." Even supposing that we could prevent the spread of the disease from human sources, what of the animal consumptives and their deadly bacilli? If the milk that we drink, and the beef, pork, and poultry that we eat, are liable to convey the infection, what hope have we of ever stopping the invasion?

The question is a serious one. But here again a thorough and careful study of the enemy's position has shown the danger to be far less than it appeared at first sight. Even bacilli have what the French call "the defects of their virtues." Their astonishing and most disquieting powers of adjustment, of accommodation to the surroundings in which they find themselves, namely, the tissues and body-fluids of some particular host whom they attack, bring certain limitations with them. Just in so far as they have adjusted themselves to live in and overcome the opposition of the body-tissues of a certain species of animals, just to that degree they have incapacitated themselves to live in the tissues of any other species.

Some of the most interesting and far-reachingly important work that has been done in the bacteriology of tuberculosis of late years has concerned itself with the changes that have taken place in different varieties and strains of tubercle bacilli as the result of adjusting themselves to particular environments. The subject is so enormous that only the crudest outlines can be given here, and so new that it is impossible to announce any positive conclusions. But these appear to be the dominant tendencies of thought in the field so far.

Though nearly all domestic animals and birds, and a majority of wild animals under captivity, are subject to the attack of tuberculosis, practically all the infections hitherto studied are caused by one of three great varieties or species of the tubercle bacillus: the human, infesting our own species; the bovine, attacking cattle; and the avian, inhabiting the tissues of birds, especially the domestic fowl. These three varieties or species so closely resemble one another that they were at one time regarded as identical, and we can well remember the wave of dismay which swept over the medical world when Robert Koch announced that the "perlsucht" of cattle was a genuine and unquestioned tuberculosis due to an unmistakable tubercle bacillus. But as these varieties were thoroughly and carefully studied, it was soon found that they presented definite marks of differentiation, until now they are universally admitted to be distinct varieties, each with its own life peculiarities, and, according to some authorities, even distinct species.

"But," we fancy we hear some one inquire impatiently, "what do those academic, technical distinctions matter to us? Whether the avian tuberculosis germ is a variety or a true species may be left to the taxonomists, but it is of no earthly importance to us."

On the contrary, it is of the greatest importance. For the distinctive feature about a particular species of parasite is that it will live and flourish where another species will die, and, vice versa, will die in surroundings where its sister species might live and thrive.

One of the first differences found to exist among these three types of bacteria was the extraordinary variation in their power of attacking different animals. For instance, while the guinea-pig and the rabbit could be readily inoculated with human bacilli, they could only be infected with difficulty by cultures of the bovine bacillus; while the only animal that could be inoculated at all with the avian or bird bacillus was the rabbit, and he only occasionally. In fact, bacteriologists soon came to the consoling conclusion that the avian bacillus might be practically disregarded as a source of danger to human beings, so widely different were the conditions in their moist and moderately warm tissues to those of the dry and superheated tissues of the bird to which it had adjusted itself for so many generations.

And next came the bold pronunciamento of no less an authority than Koch himself, that the bovine bacillus also was so feebly infective to human beings that it might be practically disregarded as a source of danger. This promptly split the bacteriologists of the world into two opposing camps, and started a warfare which is still being waged with great vigor. As the question is still under hot dispute by even the highest authorities, it is, of course, impossible to pronounce any definite conclusions. But the net result to date appears to be that while Koch made a serious error of judgment in declaring that meat and milk as a source of danger to human beings of tuberculosis might be disregarded, yet, for practical purposes, his position is, in the main, correct: the actual danger from the bovine bacillus to human beings is relatively small.

There was nothing whatever improbable, in the first place, in the correctness of Koch's position.

It is one of the few consoling facts, well known to all students of comparative pathology or the diseases of the different species of animals, how peculiarly specialized they are in the choice of their diseases, or, perhaps, to put it more accurately, how particular and restricted disease-germs are in their choice of a host. For instance, out of twenty-eight actually infectious diseases which are most common among the domestic animals and man, other than tuberculosis, only one—rabies—is readily communicable to more than three species; only three—anthrax, tetanus, and foot-and-mouth disease—are communicable to two species; while the remainder are almost absolutely confined to one species, even though this be thrown into closest contact with half a dozen others.

Again, we have half a dozen similar instances in the case of tuberculosis itself. The horse and the sheep, for instance, are both most intimately associated with cattle, pastured in the same fields, fed upon the same food, and yet tuberculosis is almost unknown in sheep and decidedly uncommon in horses, and when it does occur in them is from a human source. The goat is almost equally immune from both human and bovine forms, while the cat and the dog, although developing the infection with a low degree of frequency, almost invariably trace that infection to a human source.

There is, therefore, no a priori reason whatever why we should be any more susceptible to bovine tuberculosis than the remainder of the domestic animals. It is only fair to say, however, that the animal whose diet—and appetite—most closely resembles ours, the hog, is quite fairly susceptible to bovine tuberculosis if fed upon the milk or meat of tuberculous cattle.

Next came the particularly consoling fact that although nothing has been more striking than the great increase in the amounts of meat and milk consumed by the mass of the community during our last twenty years' progress in civilization, this has been accompanied not by any increase of tuberculosis, but by a diminution of from thirty-five to forty-five per cent. The allegation so frequently made that there has been an increase in the amount of infantile tuberculosis has been shown, upon careful investigation by Shennan of Edinburgh, Guthrie of London, Kossel in Germany, Comby in France, Bovaird in New York, and others, to be practically without foundation.

Then, while repetitions of Koch's experiment, upon which his announcement was based, of inoculating calves and young cattle with human bacilli have proved that a certain number of them can be, under appropriate circumstances, made to develop tuberculosis, that number has never been a large percentage of the animals tested, and in many cases the infection has been a local one, or of a mild type, which has resulted in recovery. Lastly, while a number of bacilli, with bovine culture and other characteristics, have been recovered from the bodies of children dying of tuberculosis, and these bacilli have proved virulent to calves when injected into them, yet, as a matter of historical fact, the actual number of instances in which children or other human beings have been definitely proved to have contracted the disease from the milk of a tuberculous cow is still exceedingly and encouragingly small. A careful study of the entire literature of the past twenty years, some three years ago, revealed only thirty-seven cases; and of these thirty-seven Koch's careful investigations have since disproved the validity of nine.

On the other hand, it is anything but safe to accept Koch's practical dictum and neglect the meat and milk of cattle as a source of danger in tuberculosis. First, because the degree of our immunity against the bovine bacilli is still far from settled; and, second, because, while bacteriologists are fairly agreed that the avian, the bovine, and the human represent three distinct and different variations, if not species, of the bacillus, they are almost equally agreed that they are probably the descendants of one common species, which may possibly be a bacillus commonly found upon meadow grasses, particularly the well-known timothy, and hence very frequently in the excreta of cattle, and known as the grass bacillus or dung bacillus of Moeller. This bacillus has all the staining, morphological, and even growth characteristics of the tubercle bacillus except that it produces only local irritation and little nodular masses, if injected into animals. Our knowledge of its existence is, however, of great practical importance, inasmuch as it warned us that in our earlier studies of the bacilli contained in milk and butter we have been mistaking this organism for a genuine tubercle bacillus. As a consequence, of late years our tests for the presence of tubercle bacilli in milk are made not only by searching for the organism with the microscope, but also by injecting the centrifugated sediment of the infected milk into guinea pigs, to see if it proves infectious. Many of our earlier statements as to the presence of tubercle bacilli in milk and butter are now invalidated on this account.

Not only are the three varieties of tubercle bacilli probably of common origin, but they may, under certain peculiar conditions, be transformed into one another, or, at least, enabled to live under the conditions favorable to one another. This was shown nearly fifteen years ago by the ingenious experiments of Nocard, the great veterinary pathologist. He took a culture of bovine bacilli, which were entirely harmless to fowls, and, inclosing them in a collodion capsule, inserted them into the peritoneal cavity of a hen. The collodion capsule permitted the fluids of the body to enter and provide food for the bacilli, but prevented the admission of the leucocytes to attack and destroy them. After several weeks the capsule was removed, the bacilli found still alive, and transferred to another capsule in another fowl. When this process had been repeated some five or six times, the last generation of bacilli was injected into another fowl, which promptly developed tuberculosis, showing that by gradually exposing the bacilli for successive generations to the high temperature of the bird's body (from five to fifteen degrees above that of the mammal), they had become acclimated, as it were, and capable of developing. So that it is certainly quite conceivable that bovine bacilli introduced in milk or meat might manage to find a haven of refuge or lodgment in some out-of-the-way gland or tissue of the human body, and there avoid destruction for a sufficiently long time to become acclimated and later infect the entire system.

This is the method which several leaders in bacteriology, including Behring (of antitoxin fame), believe to be the principal source and method of infection of the human species. The large majority, however, of bacteriologists and clinicians are of the opinion that ninety per cent of all cases of human tuberculosis are contracted from some human source. So that, while we should on no account slacken our fight against tuberculosis in either cattle or birds, and should encourage in every way veterinarians and breeders to aim for its total destruction,—a consummation which would be well worth all it would cost them, purely upon economic grounds, just as the extermination of human tuberculosis would be to the human race,—yet we need not bear the burden of feeling that the odds against us in the fight for the salvation of our own species are so enormous as they would be, had we no natural protection against infection from animals and birds.

The more carefully we study all causes of tuberculosis in children, the larger and larger percentage of them do we find to be clearly traceable to infection from some member of the family or household. In Berlin, for instance, Kayserling reports that seventy per cent of all cases discovered can be traced to direct infection from some previous human case.

Lastly, what of the left wing of our army of extermination, composed of those light-horse auxiliaries—the general progress and new developments of civilization, and the net results upon the individual of the experiences of his ancestors, which we designate by the term "heredity"? For many years we were in serious doubt how far we could depend upon the loyalty of this group of auxiliaries, and many of the faint-hearted among us were inclined to regard their sympathies as really against us rather than with us, and prepared to see them desert to the enemy at any time. It was pointed out, as of great apparent weight, that consumption was decidedly and emphatically a disease of civilization; that it was born of the tendency of men to gather themselves into clans and nations and crowd themselves into villages and those hives of industry called cities; that the percentage of deaths from tuberculosis in any community of a nation or any ward of a city was high in direct proportion to the density of its population; and that the whole tendency of civilization was to increase this concentration, this congestion of ground space, this piling of room upon room, of story upon story. How could we possibly, in reason, expect that the influences which had caused the disease could help us to cure it?

But the improbable has already happened. Never has there been a more rapid and extraordinary growth of our great cities as contrasted with our rural districts, never has there been a greater concentration of population in restricted areas than during the past thirty-five years. And yet, the prevalence of tuberculosis in that time, in all civilized countries of the earth, has shown not only no increase, but a decrease of from thirty-five to fifty per cent. To-day the world power which has the largest percentage of its inhabitants gathered within the limits of its great cities, England, has the lowest death-rate in the civilized world from tuberculosis, although closely pressed within the last few years by the United States, whose percentage of urban population is almost equally large, while England's sister island, Ireland, with one of the highest percentages of rural and the lowest of urban population, has one of the highest death-rates from tuberculosis, and one which is, unfortunately, increasing.

The real cure for the evils of civilization would appear to be more civilization, or, better, perhaps, higher civilization. Nor are these exceptional instances. Take practically any city, state, or province in the civilized world, which has had an adequate system of recording all births and deaths for more than thirty years, and you will find a decrease in the percentage of deaths from tuberculosis in that time of from twenty to forty per cent. The city of New York's death-roll, for instance, from tuberculosis, per one thousand living, is some thirty-five per cent less than it was thirty years ago. So that our fight against the disease is beginning to bear fruit already. As Osler puts it, we run barely half the risk of dying of tuberculosis that our parents did and barely one-fourth of that of our grandparents.

But this gratifying improvement goes deeper, and is even more significant than this. It is, of course, only natural to expect that our vigorous fight against the spread of the infection of the disease would give us definite results. But the interesting feature of the situation is that this diminution in England and in Germany, for instance, began not merely twenty, but thirty, forty, even fifty years ago—two decades before we even knew that tuberculosis was an infectious disease with a contagion that could be fought.

In the case of England, for instance, we have the, at first sight, anomalous and even improbable fact that the rate of decline in the death-rate from tuberculosis for the twenty years preceding the discovery of Koch's bacillus was almost as great as it has been in the twenty years since. In other words, the general tendency, born of civilization, toward sanitary reform, better housing, better drainage, higher wages and consequently more abundant food, rigid inspection of food materials, factory laws, etc., is of itself fighting against and diminishing the prevalence of the "great white plague" by improving the resisting power and building up the health of the individual. Civilization is curing its own ills.

It must be remembered that vital statistics, showing the decrease of a given disease within the past forty or fifty years, probably represent not merely a real decrease of the amount indicated by the figures but an even greater one in fact; because each succeeding decade, as our knowledge of disease and the perfection of our statistical machinery improves and increases, is sure to show a prompter recognition and a more thorough and complete reporting of all cases of the disease occurring. Statistics, for instance, showing a moderate apparent rate of increase of a disease within the last thirty years are looked upon by statisticians as really indicating that it is at a standstill. It is almost certain that at least from ten to twenty per cent more of the cases actually occurring will be recognized during life and reported after death than was possible with our more limited knowledge and less effective methods of registration thirty years ago. So we need not hesitate to encourage ourselves to renewed effort by the reflection that we are enlisted in a winning campaign, one in which the battle-line is already making steady and even rapid progress, and which can have only one termination so long as we retain our courage and our common-sense.

This decline of the tuberculosis death-rate is, of course, only a part of the general improvement of physique which is taking place under civilization. If we could only get out from under the influence of the "good old times" obsession and open our eyes to see what is going on about us! There is nothing mysterious about it. The soundest of physical grounds for improving health can be seen on every hand. We point with horror, and rightly, to the slum tenement house, but forget that it is a more sanitary human habitation than even the houses of the nobility in the Elizabethan age. We become almost hysterical over the prospect that the very fibre of the race is to be rotted by the adulteration of our food-supply, by oleomargarine in the butter, by boric acid in our canned meats, by glucose in our sugar, and aniline dyes in our candies, but forget that all these things represent extravagant luxuries unheard of upon the tables of any but the nobility until within the past two hundred, and in some cases, one hundred, years. Up to three hundred years ago even the most highly civilized countries of Europe were subject to periodic attacks of famine; our armies and navies were swept and decimated with scurvy, from bad and rotten food-supplies; almost every winter saw epidemics breaking out from the use of half-putrid salted and cured foods; only forty years ago, a careful investigation of one of our most conservative sociologists led him to the conclusion that in Great Britain thirty per cent of the population never in all their lives had quite as much as they could eat, and for five months out of the year were never comfortably warm. The invention of steam, with its swift and cheap transportation of food-supplies, putting every part of the earth under tribute for our tables, meat every day instead of once a week for the workingman, and the introduction of sugar in cheap and abundant form, with the development of the dietary in fruits and cereals which this has made possible, have done more to improve the resisting power and build up the physique of the mass of the population in our civilized communities, than ten centuries of congestion and nerve-worry could do to break it down.

We shake our heads, and prate fatuously that "there were giants in those days," ignorant of the thoroughly attested fact, that the average stature of the European races has increased some four inches since the days of the Crusaders, as shown by the fact that the common British soldier of to-day—Mr. Kipling's renowned "Tommy Atkins," who is looked upon by the classes above him in the social scale as a short, undersized sort of person—can neither fit his chest and shoulders into their armor, get his hands comfortably on the hilts of their famous two-handed swords, nor even lie down in their coffins.

We are at last coming to acknowledge with our lips, although we scarcely dare yet to believe it in our heart of hearts, that not merely the death-rate from tuberculosis, but the general death-rate from all causes in civilized communities, is steadily and constantly declining; that the average longevity has increased nearly ten years within the memory of most of us, chiefly by the enormous reduction in the mortality from infant diseases; and that, though the number of individuals in the community who attain a great or notable age is possibly not increasing, the percentage of those who live out their full, active life, play their man's or woman's part in the world, and leave a group of properly fed, vigorous, well-trained, and educated children behind them to carry on the work of the race, is far greater than ever before. Even in our much-denounced industrial conditions, made possible by the discovery of steam with its machinery and transportation, the gain has far exceeded the loss. While machinery has made the laborer's task more monotonous and more confining, the net result has been that it has shortened his hours and increased his efficiency.

Even more important, it has increased his intelligence by demanding and furnishing a premium for higher degrees of it. Naturally, one of the first uses which he has made of his increased intelligence has been to demand better wages and to combine for the enforcement of his demands. The premium placed upon intelligence has led both the broader-minded, more progressive, and more humane among employers, and the more intelligent among employees, to recognize the commercial value of health, and of sanitary surroundings, comfort, and healthy recreations, as a means of promoting this. The combined results of these forces are seen in the incontestable, living fact that the death-rate from tuberculosis among intelligent artisans and in well-regulated factory suburbs is already below that of many classes of outdoor and even farm laborers, whose day is from twelve to fourteen hours, and whose children are worked, and often overworked, from the time that they can fairly walk alone, with as disastrous and stunting results as can be found in any mine or factory. Child-labor is one of the oldest of our racial evils, instead of, as we often imagine, the newest.

All over the civilized world to-day the average general death-rate of each city, slums included, is now below that of many rural districts in the same country. If I were to be asked to name the one factor which had done more than any other to check the spread and diminish the death-rate from tuberculosis I should unhesitatingly say, the marked increase of wages among the great producing masses of the country, with the consequent increased abundance of food, better houses, better sanitary surroundings, and last, but not least, shorter hours of labor.

Underfeeding and overwork are responsible for more deaths from tuberculosis than any other ten factors. Rest and abundant feeding are the only known means for its cure.

This is one of the reasons why the medical profession has abandoned all thought of endeavoring to fight the disease single-handed, and is striving and straining every nerve to enlist the whole community in the fight. Its burden rests, not upon the unfortunate individual who has become tuberculous, but upon the community which, by its ignorance, its selfishness, and its greed, has done much to make him so. What civilization has caused it is under the most solemn obligation to cure.

One more brigade of irregular troops on the extreme left remains to be briefly reviewed, and that is those forces resulting from the successive exposure of generations to the physical influences of civilization, including the infectious diseases. For years we never dreamed of even attempting to raise any levies among these border tribes of more than doubtful loyalty. Indeed, they were supposed to be our open enemies.

When we first attempted to take a world-view of tuberculosis, the first great fact that stood out plainly was that it was emphatically a disease of the walled town and the city; that the savage and the nomad barbarian were practically free from it; that range cattle and barnyard fowls seldom fell victims to it, while their housed and confined cousins in the dairy barn and the breeding-pens suffered frightfully. It was one of our commonplace sayings that we must "get back to nature," get away from the walled city into the open country, revert from the conditions of civilization in a considerable degree to those of barbarism, in order to escape. While, as for heredity, its influence was almost dead against us. How could a race be exposed to a disease like tuberculosis, generation after generation, without having its vital resistance impaired?

But a marked and cheering change has come over our attitude to this wing of the battle of life. So far from regarding it as in any sense necessary to revert to barbarism, still less to savagery, for either the prevention or the cure of disease, we have discovered by the most convincing, practical experience, that we can, in the first place, with the assistance of the locomotive and trolley, combined with modern building skill and sanitary knowledge, put even our city-dwellers under conditions, in both home and workshop, which will render them far less likely to contract tuberculosis than if they were in a peasant's cottage or the average farmhouse or merchant's house of a hundred years ago, to say nothing of the cave, the dugout, or the hut of the savage.

In the second place, instead of simply "going back to nature" and living in brush-shelters on what we can catch or shoot, it takes all the resources of civilization to place our open-air patients in the ideal conditions for their recovery. Let any consumptive be reckless enough to "go back to nature," unencircled by the strong arm of civilized intelligence and power, and unprotected by her sanitary shield, and nature will kill him three times out of five. There could not be a more dangerous delusion than the all-too-common one—that all that is necessary for the cure of consumption is to turn the victim loose among the elements, even in the mildest and most favorable of climates.

He must be fed upon the most abundant and nutritious of foods, even the simplest being milk of a richness which is given by no kind of wild cattle, and which, indeed, only the most carefully bred and highly civilized strains of domestic cattle are capable of producing; eggs such as are laid by no wild bird or by any but the most highly specialized of domestic poultry at the season of the year when they are most required; steaks and chops, hams and sides of bacon, sugar and fruits and nuts, which simply are not produced anywhere outside of civilization, and often only in the most intelligent and progressive sections of civilized communities.

Put him upon even the average diet of many people in this progressive and highly civilized United States the year round,—with its thin milk, its pulpy, half-sour butter, its tough meat, its half-rancid pickled pork, its short three months of really fresh vegetables and good fruit, and six months of eternal cabbage, potatoes, dried apples, and prunes,—and he will fail to build up the vigor necessary to fight the disease, even in the purest and best of air.

The saddest and most pitiful tragedies which the consumptive health-resort physician can relate are those of wretched sufferers,—even in a comparatively early stage of the disease,—whose misguided but well-meaning friends have raised money enough to pay their fare out to Colorado, California, Arizona, or New Mexico, and expect them to get work on a ranch, so as to earn their living and take the open-air treatment at the same time.

Three things are absolutely necessary for a reasonable prospect of cure of consumption. One is, abundance of fresh air, day and night. Another, abundance of the best quality of food. And the third, absolute—indeed, enforced—rest during the period of fever. Let any one of these be lacking, and your patient will die just as certainly as if all three were. Not one in five of those who go out to climates with even a high reputation as health-resorts—expecting to earn their own living or to "rough it" in shacks or tents on three or four dollars a week, doing their own cooking and taking care of themselves—recovers. They have a four-to-one chance of recovery in any climate in which they can obtain these three simple requisites, and a four-to-one chance of dying in any climate in which any one of these is lacking.

Instead of nature being able to cure the consumptive unaided, as a matter of fact she has neither the ability nor the inclination to do anything of the sort. There is no class of patients whose recovery depends more absolutely upon a most careful and intelligent study and regulation of their diet, of every detail of their life throughout the entire twenty-four hours, and of the most careful adjustment of air, food, heat, cold, clothing, exercise, recreation, by the combined forces of sanitarian, nurse, and physician. So that, instead of feeling that only by reverting to savagery can consumption be prevented, we have no hesitation in saying that it is only under civilization, and civilization of the highest type, that we have any reasonable prospect of cure.

Finally, we are getting over our misgivings as to the intentions of the hereditary brigade. It is certainly not our enemy, and may probably turn out to be one of our best friends.

Our first sidelight on this question came in rather a surprising manner. It was taken for granted, almost as axiomatic, that if the conditions of savage life were such as to discourage, if not prevent, tuberculosis, certainly, then, the race which had been exposed to these conditions for countless generations would have a high degree of resisting power to the disease. But what an awakening was in store for us! No sooner did the army surgeon and medical missionary settle down in the wake of that extraordinary world-movement of Teutonic unrest, which has resulted in the colonization of half the globe within the past two or three hundred years, than it was discovered that, although the hunting or nomad savage had not developed tuberculosis, and the disease was emphatically born of civilization, yet the moment that these healthy and vigorous children of nature were exposed to its infection, instead of showing the high degree of resisting power that might be expected, they died before it like sheep.

From all over the world—from the Indians of our Western plains, the negroes of our Southern States, the islanders of Polynesia, New Zealand, Hawaii, Samoa—came reports of tribes practically wiped out of existence by the "White Plague" of civilization. To-day the death-rate from tuberculosis among our Indian wards is from three to six times that of the surrounding white populations. The negro population of the Southern States has nearly three times the death-rate of the white populations of the same states. Instead of centuries of civilization having made us more susceptible to the disease than those savages who probably most nearly parallel our ancestral conditions of a thousand to fifteen hundred years ago, we seem to have acquired from three to five times their resisting power against it. Not only this, but those races among us which have been continuous city-dwellers for a score of generations past have acquired a still higher degree of immunity.

In every civilized land the percentage of deaths from tuberculosis among the Jews, who, from racial and religious prejudices, have been prisoners of the Ghetto for centuries, is about half to one-third that of their Gentile neighbors. In certain blocks of the congested districts of New York and Chicago, for instance, the Jewish population shows a death-rate of only one hundred and sixty-three per hundred thousand living, while the Gentile inhabitants of similar blocks show the appalling rate of five hundred and sixty-five. Similarly, by a strange apparent paradox, the highest mortality from tuberculosis in the United States is not in those states having the greatest urban population, but, on the contrary, in those having the largest rural population.

The ten highest state tuberculosis death-rates contain the names of Tennessee, Kentucky, West Virginia, Virginia, and South Carolina, while New York, Pennsylvania, and Massachusetts are among the lowest.

The subject is far too wide and complicated to admit of any detailed discussion here. But, explain it as we may, the consoling fact remains that civilized races, including slum-dwellers, have a distinctly lower death-rate from tuberculosis than have savage tribes which are exposed to it even under most favorable climatic and hygienic conditions; that those races which have survived longest in city and even slum surroundings have a lower death-rate than the rest of the community under those conditions; and that certain of our urban populations have lower death-rates than many of our rural ones.

As for the immediate effect of heredity in the production of the disease, the general consensus of opinion among thoughtful physicians and sanitarians now is that direct infection is at least five times as frequent a factor as is heredity; that at least eight-tenths of the cases occurring in the children of tuberculous parents are probably due to the direct communication of the disease, and that if the spread of the infection could be prevented, the element of heredity could be practically disregarded.

We are inclined to regard even the well-marked tendency of tuberculosis to attack a considerable number of the members of a given family to be due largely, in the first place, to direct infection; secondly, to the fact that that family were all submitted to the same unfavorable environment in the matter of food, of housing, of overwork, or of the New England conscience, with its deadly belief that "Satan finds some mischief still for idle hands to do."

Upon direct pathological grounds nothing is more definitely proven than that the actual inheritance of tuberculosis, in the sense of its transmission from a consumptive mother to the unborn child, is one of the rarest of occurrences. On the other hand, the feeling is general that, inasmuch as probably four-fifths of us are repeatedly exposed to the infection of tuberculosis and throw it off without developing a systemic attack of the disease, the development of a generalized infection, such as we term consumption, is in itself a sign of a resisting power below the average. Should such an individual as this become a parent, the strong probability is that his children—unless, as fortunately often happens, their other parent should be as far above the average of vigor and resisting power—would not be likely to inherit more vigor than that possessed by their ancestry. So that upon a priori grounds we should expect to find that the children born of tuberculous parents would be more susceptible to the infection to which they are so sure to be exposed than the average of the race. So that the marriage of consumptives should, unquestionably, upon racial grounds, be discouraged except after they have made a complete recovery and remained well at least five years.

To sum up: while the earlier steps of civilization unquestionably provide that environment which is necessary for the development of tuberculosis, the later stages, with their greatly increased power over the forces of nature, their higher intelligence and their broader humanity, not merely have it in their power to destroy it, but are already well on the way to do so.