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2. That in specially prepared and suitable media artificial cultures of the tubercle-
bacillus from bovine and human sources have produced indistinguishable effects
when they have been employed to infect a variety of animals, which would seem
to indicate that the conditions produced are only variations of one and the same
disease.
3. That tuberculin° produces a specific reaction in tuberculous cattle, whether human
or bovine tubercle-bacilli have been employed in its preparation.—(MacFadyean.)
[ It will be seen that these three reasons have relation to the theory of the
identity of bovine and human tuberculosis.]
4. That because the tubercle-bacilli derived from bovine source's is, either by
inoculation or ingestion as food, admittedly very virulent and dangerous for such
diverse species of animals as the rabbit, horse, dog, pig, sheep, and cow, it is
highly probable that it is also dangerous to man.f For it is well known that the
majority of disease-producing bacteria are harmful to only one or two species of
animals, but those disease-producing bacteria that are common to all the
domesticated animals are also able to produce disease in man.
5. That the statistics and percentages set forth by Dr. Koch with regard to primary
intestinal tuberculosis cannot be accepted as representing universal experience.
For example, in two separate reports from two children's hospitals in London and
Edinburgh dealing with 547 cases of death from tuberculosis in children, it
appears that 29.1 per cent, and 28.1 per cent, of the cases respectively primary
infection appeared to have taken "place through the intestine. But quite apart
from statistics, the whole question of such primary intestinal tuberculosis (which
Dr. Koch held as the only acceptable evidence of tuberculous infection through
milk and meat) is fraught with many difficulties and fallacies, and is at present
sub judice. It has been shown by Professor Sidney Martin and others that
primary intestinal tuberculosis may not be, by any means, an invariable criterion
of tubercular infection by means of food (vide infra).
6. That there are on record a number of cases in which there appeared to be
substantial evidence to show that persons had contracted tuberculosis, directly or
indirectly, by means of milk or meat. It is obvious that such cases, unless
occurring with extraordinary frequency, are only of relative value. Moreover, there
are other channels of infection to eliminate, and this it is often impossible to do.
7. That the results obtained from the inoculation of human tubercle into animals by
Dr. Koch cannot be accepted as in complete accord with universal experience. In
England alone somewhat similar experiments have been performed having positive.•
results.
Several years ago Professor Crookshank carried out such an experiment. He obtained
sputum containing numerous tubercle-bacilli from an advanced case of human consumption.
This was injected into the peritoneal cavity of a healthy calf. The animal became ill and
died 42 days after inoculation from jjycemia (blood-poisoning). On post-mortem examination
it was found that there were abundant signs of generalized tuberculosis.‡ This calf
was not tested with tuberculin previously to the experiment.
Professor Sidney Martin carried out the following experiments for the Royal Commission
on Tuberculosis. £
° Tuberculin is a product of the artificial cultivation of the tubercle-bacillus (human or bovine)
which is now used as an injection test into cattle. If such cattle are suffering from tuberculosis they
"react" (giving high temperature, swelling at the point of inoculation, etc.) ; if not so suffering, they do
not react. Hence tuberculin is used as a diagnostic agent.
†See the researches of Villemin (1865), Klebs, Chauveau (1868), Gerlach, Giinther and Harms (18701873),
Bollinger, and others. Further, Frledberger and Frohner state in their Veterinary Pathology that
Wesener compiled reports up to 1884 of 369 feeding experiments, the positive and negative results of which
were about equal in number. From this compilation it appears that (a) 71 animals, among which guineapigs
and swine proved most susceptible, were experimented upon with human tubercular matter; (6) 180
experiments were made with tubercular matter from cattle ; (c) the flesh of tuberculous cattle was given
on 32 occasions as food, with the result that pigs were found to be more susceptible than other animals, and
that dogs were unaffected ; and (d) the milk of tuberculous cows was given as food in 86 cases. From these
experiments it was found that in the scale of comparative racial susceptibility the herbivora (cattle,
sheep, goats) proved highest, then swine, and after these guinea-pigs and rabbits. Carnivorous animals
were little affected. Bovine tubercular matter was found to possess the greatest power of infection,
then came the sputum of tuberculous men, then the milk of tuberculous animals, and lastly, tuberculous
flesh.
‡Bacteriology and Infective Diseases.—Edgar M. Crookshank, 1896, pp. 389-391.
§ Report of the Royal Commission appointed to inquire into the Effect of Food derived from Tuberculous
Animals on Human Health, 1895. Part iii., Appendix, pp. 18 and 19.