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bad atmosphere, bad health, etc. But with all this, the fact remains that under the same conditions certain individuals are affected in various degrees of intensity, and certain others escape entirely. Many ingenious theories have been invented and proposed to explain this anomaly. Finally Stilling found that in myopic individuals the roof of the orbit is comparatively flat. Thus the insertion of the superior oblique muscle is dislocated to make the change of shape in the eyeball upon which the myopia depends. But myopia develops only in those individuals when they are subjected to eye-strain. These individuals are said, therefore, to be predisposed to myopia. The anatomical anomaly is the predisposition to myopia.
Is there, in this sense, a predisposition peculiar to phthisis? Koster finds it as Hippocrates did before him, in the paralytic thorax, which permits the easier colonization and multiplication of bacilli at the apices of the lungs. Such apices receive no fresh air at all. They inspire only gases and bacteria from other parts of the lungs. We have, he says, not so much to combat the bacillus as the disposition, that is, the build of the thorax, etc.
Wolff declares also that the danger of infection, at least in adults, is of far less importance than the danger of the disposition. He goes so far as to maintain that when an individual becomes tuberculous, it is useless to investigate the past for the occasion of the infection. Infection may reach far back into childhood. Klebs is a decided advocate of a certain disposition as a necessity to tuberculous infection, and Hiller emphasizes the fact to such extent as to say that it is not so much a question of infection with tubercle parasites as of the presence of an individual bodily predisposition. If a man has this predisposition, he says, what would it avail to keep the bacilli out of his lungs for a certain time? When we consider the universal distribution of them, we must recognize that in such an individual infection is a mere question of time. The treatment, therefore, is not the treatment of the disease, but the combat of the individual tuberculous
disposition. From this standpoint, Volland asks, "how shall a man protect himself from consumption?" The only proper answer is, he says, that a man protect himself as much as possible from acquiring the disposition. For those in whom the condition has occurred in childhood, this advice is too late.
These authorities all assume it, but, aside from the paralytic thorax mentioned, no one of them attempts to define the disposition in any way.
Sometimes this disposition is said to be acquired, sometimes it is inherited. With the subject of inheritance, the question of disposition takes at once a wider range. May not the disease itself be inherited, that is, may not the tubercle bacillus be directly transmitted to the offspring? This question necessitates at once a revision or readjustment of definitions. It shows at once a misconception of the term and a confusion of disposition with causation, for a direct transmission is not a disposition. It is the disease itself, and if transmission be true in all cases, it renders any study of predisposition superfluous. Even though latent, we do not say of a child born with syphilis that it is born with a disposition, but with the disease itself. Hence the question of direct transmission by heredity must be disposed of first.
Goldsmith says that man first gapes with wonder at the mysteries about him and it is only when he ceases to wonder that he begins to study and observe. During the wonder period he has the credulity of a child and his mind is satisfied with any explanation. It suffices at first to be told that the universe was created. As for tuberculosis, it was inherited.
With our immediate forefathers it was assumed, as the easiest explanation, that tuberculosis was always inherited. The only question with them was as to the degree of the descent, or of the relationship included. From what we know of the universality of the disease, we know that it is always possible to find phthisis somewhere in the ancestry. The proportion widens of course with extent of relationship
included. Thus, of the 1010 cases at the Brompton Hospital, including only parents, the report shows an average of 24.4 per cent. Cotton's 1000 cases, including parents, brothers and sisters, gave 36.7 per cent. Fuller's 385 cases included grandparents, uncles and aunts, and furnished about 60 per cent., and so on. But nowadays, outside of comic opera, we do not reckon inheritance from uncles, cousins and aunts. Williams estimates from his 1000 cases an average of 12 per cent. for direct hereditary predisposition, and 84 per cent. for what he calls family predisposition. Would anybody now seriously contend for inheritance of a disease from outside cause from grandparents? Attention may here be called to the fact that while 43 of his cases had the father alone infected, 67 had the mother alone affected, and 224 had brothers and sisters affected with the disease. Surely this fact speaks stronger in favor of infection than heredity. The trouble with heredity is that it does not explain enough. It is admitted that of 100 cases affected with phthisis, 12 or 24 will have had tuberculous parents, but if we recall the fact that these 100 patients had 200 parents, it will be seen that these numbers represent heredity in but one sixteenth, or one-eighth of the cases, whereas we know already that tuberculosis is fatal in the lungs alone to one-sixth or oneseventh of mankind. We say of cancer sometimes that the role of heredity appears in eighteen per cent. of cases, not enough to make it merit consideration. We speak of the eloquence of figures. That depends upon what we want to prove. We forget sometimes that a figure is also a mode of speech. "One may prove anything with figures," is a proverb; and when we speak "figuratively" we intend to represent something else. Tallyrand said: "Si c'est un mensonge c'est les chiffres." But so far as figures speak here they prove nothing for the heredity of tuberculosis.
Advocates of heredity find support in the fixation of the disease in families. Thus Riffel declares that the families of two villages in Baden showed the disease more than one hundred years. Riffel made, as Langenhausen made before
him, regular genealogical trees of families affected with tuberculosis. It is thus shown that where tuberculosis had once occurred in a family, it fixed itself with tenacity and remained up to the present time, following members of it relentlessly to extinction. Neither distance nor the introduction of healthy individuals upon the old trunk have sufficed to bar the descent of tuberculosis to posterity. The influence of the inherited disposition continues, he declares, even if a generation escapes attack. In fact, it suffices, as many examples show, to introduce one individual, hereditarily affected, though he may himself not be tuberculous, into a previously healthy family, to introduce the disposition to the entire posterity.
This author goes further. "It is remarkable," he says, "that a husband, himself from a healthy family, introduced into a family notoriously predisposed by inheritance, does not himself succumb to tuberculosis, but he may see fade before him his wife, children and grandchildren under the disease." Men who pursued this train of thought reached the conclusion of Riffel, that the tubercle bacillus is not the producer, but is only the attendant of tuberculosis.
Another factor in support of inheritance is the predominance in children of gland, bone and joint affections, recesses of the body not open to direct invasion from the outside, and reached only through the avenue of the blood and lymph channels. Scrofula is certainly much more frequent in childhood, but scrofula is an outside disease. It is just under the skin and in the line of the lymphatics from the throat. Disease of the bone and joints in the earliest life, that is in the earliest weeks and months of life, are far more frequently due to syphilis than to tuberculosis. Hip joint disease, white swelling of the knee, Pott's caries, creations of tuberculosis, almost never show themselves in the first months, and rarely in the first years of life. Nevertheless it is true that tuberculous bone and joint affections are most common in later childhood. Here, however, may be mentioned the discovery of Schede that many of the intensely chronic rheumatisms of old age are tuberculous.
The advocates of inheritance also claim tuberculosis of the skin as a hematogenous infection, but surely this should have been the last resort, for the skin is the very outside and lupus or other skin tuberculosis is almost never found in conjunction with any internal deposit.
When we come to the scientific study of inheritance of a disease produced by a distinct cause, we observe that the subject falls at once into two divisions, to wit: Transmission at conception, that is with the spermatozoid or ovum, and inoculation later in intra-uterine life from a infected mother. Sometimes these divisions are differentiated as conceptional or germinative, and congenital, but these terms are so often used synonymously, or the latter for both, as to lead to confusion. It must be at once admitted that there is no way of ascertaining whether a fetus was infected in the ovary or in the uterus, so that positive proof of absolute inheritance can be adduced only from the side of the father. As for congenital tuberculosis, i. e., infection from the mother, it is not only possible, but proven, but only as the great exception, not so often, for instance as in the case of smallpox.
Max Wolff inoculated a number of pregnant animals with tuberculous matter, and a second set of animals before they become pregnant. These experiments were not favorable to the view of transmission of the bacilli. This author did not inoculate males. Wolff maintains that in by far the greatest number of cases of so-called congenital tuberculosis the disease has been acquired by infection after birth.
Baumgarten, who has always been the strongest advocate of hereditary tuberculosis, collected all the observations which could substantiate his view. He appeals in the first place to the tuberculosis of birds, as of chickens, though the disease is here caused by a special species. In these animals in the absence of sputum or of feces containing bacilli, dissemination by the outside world is scarcely possible. He appeals to the fact also that in man cases of congenital tuberculosis are no longer so very rare. To be exact here, too,