under the skin, in others into the peritoneal cavity, and in others into the jugular vein. None
of these 19 cattle showed any symptoms of disease. After 6 to 8 months they were killed,
and in their internal organs not a trace of tuberculosis was found. The result was utterly
different, however, when the same experiment was made on cattle free from tuberculosis
with tubercle bacilli from bovine sources. In this case virulent tuberculosis rapidly supervened.
Further, an almost equally striking distinction between human and bovine tuberculosis
was brought to light by a feeding experiment with swine. Six young swine were
fed daily for three months with the tubercular sputum of consumptive patients. Six other
swine received bacilli of bovine tuberculosis with their food daily for the same period. The
animals that were fed with sputum remained healthy and grew lustily, whereas those that
were fed with the bacilli of bovine tu'igrculosis soon became sickly, were stunted in their
growth and half of them died. After tlffie months and a half the surviviifg swine were all
killed and examined. Among the animals that had been fed with sputum no trace of tuberculosis
was found, except her1 and there little nodules in the lymphatic glands of the neck,
and in one case a few grey nodules in the lungs. The animals, on the other hand, which
had eaten bacilli of bovine tuberculosis had, without exception (just as in the cattle experiment),
severe tubercular diseases, especially tubercular infiltration of the greatly enlarged
lymphatic glands of the neck and of the mesenteric glands, and also extensive tuberculosis
of the lungs and the spleen. The difference between human and bovine tuberculosis
appeared not less strikingly in a similar experiment with asses, sheep, and goats, into whose
vascular systems the two kinds of tulercle-bacilli were injected.*
Dr. Koch also stated that other experiments in former times, and recently in America,
have led to the same result.
In support of his second contention, namely, that bovine tuberculosis is not transmissible
to man, Dr. Koch points out that the direct experiment upon human beings is, of
course, out of the question, and hence it is necessary to rely upon indirect evidence.
Dr. Koch, therefore, reasons as follows : Tuberculosis, caused by meat or milk, can be
assumed with certainty only when the intestine suffers first, i.e., when a so called "primary
tuberculosis" of the intestine is found. If bovine tubercle bacilli are capable of causing
disease in man there are abundant opportunities for the transference of the bacilli from one
species to the other, and cases of primary intestinal tuberculosis from consumption of
tuberculous milk ought therefore to be of common occurrence. "But such cases," he
maintains, "are extremely rare." In support of this view Dr. Koch stated that he had
only seen two cases; that only ten cases had been met with in the Charite Hospital in
Berlin; and that out of 3,104 fiost mortems of tubercular children, Biedert observed only
16 cases. Reference was also made to other similar evidence.
Finally, Dr. Koch maintained that "though the important question whether man is
"susceptible to bovine tuberculosis at all is not yet absolutely decided, and will not admit of
"absolute decision to-day or to-morrow, one is, nevertheless, already at liberty to say
"that if such a susceptibility really exists the infection of human beings is but a very
" rare occurrence."
Such are briefly the facts of the case as set forth by Dr. Koch at the Congress.
Coming, as these views do, on the highest possible authority, they must command the
respect and attention of the entire scientific world.
It is right, however, that the Committee, for the reasons already stated, should have
before them some of the evidence upon the other side, and upon which the protective and
legislative measures so widely adopted in Great Britain are based.
At the Congress Lord Lister (London), Professor Nocard (Alfort), Professor Bang
(Copenhagen), Professor Crookshank (London), Professor Woodhead (Cambridge),
Professor MacFadyean (London), and many other authorities expressed themselves as
unable at the present time to accept the views of Dr. Koch. Since the Congress many
other authorities have also expressed themselves in a similar way. Professor Virchow, of
Berlin, has stated that whilst he is in agreement with certain views expressed by Dr. Koch at
the British Congress, he is not satisfied with the evidence furnished in support of the
contention that bovine tuberculosis is not transmissible to man. Professor Ivlebs (Berlin)
is also of the same opinion.
The following are the chief reasons for supposing that bovine and human tuberculosis
are one and the same disease, and intercommunicable:—
1. That the tubercle-bacillus of bovine tuberculosis possesses characteristics of shape,
size, staining, and cultivation on artificial media similar to, and in the opinion of
many authorities almost identical with, the tubercle-bacillus of human origin.
º Dr. Koch's evidence is here quoted as much as possible in his own words.