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1. Four pigs were fed upon bovine tuberculous material (meat and milk) and contracted
tuberculosis. In commenting upon the post-mortem signs Dr. Martin says:—
"In the tuberculosis resulting from feeding pigs with the meat and milk of tuberculous cows the absence of any lesion [abrasion, nodule, or other mark of disease]
"in the alimentary tract is very noticeable, so that the disease is first shown in
"its course from the alimentary tract by an affection of the lymph glands in
"connexion with the different parts of that tract." And againThe chief
"points to be noticed in these results as they bear on tuberculosis in the human
"being is that by feeding with tuberculous material there may be no lesion in the
"alimentary tract; that there may be absorption only through the pharynx and
''tonsil producing tuberculosis o'i the connected lymph gland, so that this connition of things exactly tallies with the ' strumous' glands of children and
" young adults. Lastly, from feeding there may be affection of the lymphatic
" glands alone."
2. Four calves received at one meal, mixed with their food, about one kilogramme of
bovine tuberculous material. They all contracted tuberculosis. Dr. Martin further
pointed out that although "from feeding calves with bovine tuberculous material
"a lesion in the form of nodules is produced in the intestine, it may not proceed
"to ulceration but remain stationary. The intestine is affected in the form of
"isolated nodules as early as four weeks after feeding. . . . The mesenteric
"glands are in all cases affected to a greater or less degree. From the intestinal
"lesion the disease in calves spreads to the lymphatic glands in the thorax and the
"lungs or pleura, or both of these."
3. Four calves received at one meal, with their food, 70 cc. of sputum (containing a large
number of tubercle-bacilli) from two cases of human consumption. Three calves
contracted tuberculosis, but in none of them was there any sign of disease except
nodules in the intestine, and in calf four every organ and gland was healthy.
Two calves received 440 cc. of human sputum containing a large number of
tubercle-bacilli. One calf contracted tuberculosis of the intestine and mesenteric
glands. The other calf remained perfectly healthy. Dr. Martin concludes that
"it is evident therefore that in the case of [human 1 tuberculous sputum we are
"dealing with material which is less infectious to calves than bovine tuberculous
"material. This lessened infectivity is possibly not merely a question of dosage,
"but one of diminished activity of the tubercle-bacilli in sputum as compared to
"its activity in the tuberculous lesion of the cow."°
Here then are the main facts in the evidence for both sides of the question under
discussion. The latter evidence tending to show the transmission of tuberculosis to man
by means of milk and meat, is part of that upon which the Royal Commission relied when
it reported, "We cannot refuse to apply, and we do not hesitate to apply, to the case of
"the human subject the evidence [of transmission of the disease j thus obtained from a
"variety of animals that differ widely in their habits of feeding—herbivora, carnivora,
"omnivora. .Is regards man we must believe that any person who takes tuberculous matter
"into the body as food incurs some risk of acquiring tuberculous disease.' ] And again,
"We have obtained ample evidence that food derived from tuberculous animals can produce
"tuberculosis in healthy animals. In the absence of direct experiments on human subjects
"we infer that man also can acquire tuberculosis by feeding upon materials derived from
tuberculous food-animals." ];
0Various circumstances ha\e in all probability contributed to render unsuccessful or irregular in
result the numerous feeding experiments which have been made. The tissues of animals ditfer greatly in
susceptibility to tuberculosis ; the infective material is exposed to tlie digestive juices which are, in
measure, germicidal, and yet not equally so ; the virulence of the infective material itself varies enormously
as does the virulence between diff;rent generations or races of tubercle-bacilli. Hence it comes about
that one animal may eat with its food a certain amount of tuberculous material and yet not develop
tuberculosis, whilst another animal of the same species might quickly develop the disease, which would in
all probability show itself at the animal's weakest point, and not always necessarily in the intestine.
Further, therp is another point which should not be overlooked, namely, tiie subsequeirt treatment of the
inoculated animal. Whilst it is essential to prove that the animal to be inoculated is free from tuberculosis,
it should be remembered that in taking very healthy animals for experiment, and in subsequently treating
them in what may be termed an " ideal " fashion, some of the very conditions essential to the production of
the disease in ordinary life are removed. As in men, so in cattle and other animals, it may be presumed
that abundance of good food and fresh air, and, in general, an ideal environment, tend to counteract the
effect of the inoculated or communicated virus. Thus such experiments as those stated above may not
always fairly represent the modes of transmission of the disease as they occur in ordinary life. It is not
the " very healthy" animal of a herd, well housed and fed, which contracts tuberculosis.
† Report of Royal Commission, 1895, Part I., p. 10, par. 22.
‡bid., p. 20, par. 77.