446 
CONGRESS ON TUBERCULOSIS. 
fection is generally regarded nowadays as proved, and as so 
frequent that it is even looked upon by not a few as the most 
important, and the most rigorous measures are demanded 
against it. In this Congress also the discussion of the danger 
with which the tuberculosis of animals threatens man will play 
an important part. Now, as my investigations have led me to 
form an opinion .deviating from that which is generally ac¬ 
cepted, I beg your permission, in consideration of the great im¬ 
portance of this question, to discuss it a little more thoroughly. 
Genuine tuberculosis has hitherto been observed in almost 
all domestic animals, and most frequently in poultry and cattle. 
The tuberculosis of poultry, however, differs so much from hu¬ 
man tuberculosis that we may leave it out of account as a pos¬ 
sible source of infection for man. So, strictly speaking, the 
only kind of animal tuberculosis remaining to be considered is 
the tuberculosis of cattle, which, if really transferable to man, 
would indeed have frequent opportunities of infecting human 
beings through the drinking of the milk and the eating of the 
flesh of diseased animals. 
Even in my first circumstantial publication on the etiology 
of tuberculosis I expressed myself regarding the identity of hu¬ 
man tuberculosis and bovine tuberculosis with reserve. Proved 
facts which would have enabled me sharply to distinguish these 
two forms of the disease were not then at my disposal, but sure 
proofs of their absolute identity were equally undiscoverable, 
and I therefore had to leave this question undecided In 
order to decide it, I have repeatedly resumed the investigations 
relating to it, but so long as I experimented on small animals, 
such as rabbits and guinea-pigs, I failed to arrive at any satis¬ 
factory result, though indications which rendered the difference 
of the two forms of tuberculosis probable were not wanting. 
Not till the complaisance of the Ministry of Agriculture enabled 
me to experiment on cattle, the only animals really suitable for 
these investigations, did I arrive at absolutely conclusive results. 
Of the experiments which I have carried out during the last 
two years along with Professor Schiitz, of the Veterinary Col¬ 
lege in Berlin, I will tell you briefly some of the most impor¬ 
tant. 
A number of young cattle which had stood the tuberculin 
test, and might therefore be regarded as free from tuberculosis, 
were infected in various ways with pure cultures of tubercle- 
bacilli taken from cases of human tuberculosis; some of them 
got the tubercular sputum of consumptive patients direct. In 
