CONGRESS ON TUBERCULOSIS. 
457 
of submitting to this Congress, I was under the impression that 
it would not be necessary to formally prove that the term tuber¬ 
culosis as it is now employed by medical men and veterinary 
surgeons relates to one and the same disease. I thought that I 
might ask my audience to accept it as proved, and generally ad¬ 
mitted, that tuberculosis in man is caused by a single definite 
species of organism—the tubercle bacillus—that this organism 
is also the cause of the disease to which veterinary surgeons ap¬ 
ply the term tuberculosis in the case of cattle and other domes¬ 
ticated species, and that there therefore existed a primct facie 
case against the germs formed in the bodies of tuberculous ani¬ 
mals as a possible source of tuberculous disease in human 
beings. 
To-day, however, the position of any one who undertakes to 
discuss the inter-communicability of human and bovine tuber¬ 
culosis is very different from what it would have been a week 
ago, for in the interval the greatest living authority on tubercu¬ 
losis—the world-renowned discoverer of the tubercle bacillus, 
and the man to whom we are mainly indebted for our knowl¬ 
edge of the cause of tuberculosis—has declared his conviction 
that human and bovine tuberculosis are practically two distinct 
diseases. I do not know how far the reasons assigned by Dr. 
Koch for the opinion which he now holds on this question may 
have commended themselves to the members of this Congress, 
and I am overwhelmed at finding myself in a position which 
compels me to offer some criticism on the pronouncement of one 
the latchet of whose shoes I am not worthy to unloose. 
That bovine and human tuberculosis are identical diseases 
was generally supposed to have been finally determined by 
Dr. Koch himself, when he discovered that the human and 
the bovine lesions contained bacilli that were identical in 
morphological, tinctorial, and cultural characters, and showed 
that the artificial cultures from both sources produced indistin¬ 
guishable effects when they were employed to infect a variety of 
animals. The labors of hundreds of workers during the suc¬ 
ceeding eighteen years produced nothing in serious conflict with 
the conclusion that human and bovine tuberculosis were iden¬ 
tical diseases, but they brought to light what appeared to be 
additional evidence of this identity, such as the discovery that 
tuberculin produced a specific reaction in tuberculous cattle, 
whether human or bovine bacilli had been employed in its prep¬ 
aration. In short, the identity of the bacilli from the two sources 
appeared to be as firmly established as any other generally ac- 
