No. 6. DEPARTMENT OP AGRICULTURE. 107 



"Boviue tubeculosis is idientical with human tuberculosis, and is 

 thus a disease transmissible to man.' This belief was the outcome 

 of the experiments made by Koch at the time of his discovery of 

 the tubercle bacillus, and has been generally accepted by the medi- 

 cal and veterinary professions up to the present time. So much has 

 been written of late on the subject that I will pass over minor ditfer- 

 ences of opinion, and at once take up the consideration of the two 

 main propositions which were formulated by Koch and which include 

 all points of controversy in the discussion of the relation between, 

 human audi bovine tuberculosis. 



1. "Human tuberculosis differs from bovine and cannot be trans- 

 mitted to cattle." 



2. "Through the important question wihether 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, never- 

 theless, already at liberty to say that if such a susceptibility really 

 exists the infection of human beings is but a very rare occurrence. 

 1 should estimate the extent of infection by the milk and flesh of 

 tuberculosis cattle, and the butter made of this milk is hardly 

 greater than that of hereditary transmission, and, therefore, do not 

 deem it advisable to t;ake any measures against it." 



I. Tihe first of these propositions is susceptible of direct experi- 

 mental investigation, and can, therefore, be answered positively with- 

 out going into the domain of theory. Prof. Koch based this state- 

 ment on the result of an insufhcient number of experiments* done 

 by Prof. Shiitz and himself. A number of young cattle proved to be 

 free from tuberculosis by the tuberculin test were infected in various 

 ways with the bacilli of human origin or with tubercular sputum. 

 "In some cases the tubercle bacilli or the sputum were injected un- 

 der the skin, in others into the peritoneal cavity, in others into the 

 jugular vein. Six animals were fed with tubercular sputum almost 

 daily for seven or eight months; four repeatedly inhaled great quan- 

 lities of bacilli, which were distributed in water and scattered with 

 it in the form of spray. None of these cattle (there were nineteen 

 of them) showed any symptoms of disease, and they gained consid- 

 erably in weight." After six to eight months tihey were killed, and 

 no trace of disease was found in the internal organs. Where the 

 injections were made, small foci of suppuration had formed, in which 

 there were found a few bacilli. 



Inoculations of a similar nature with bacilli from the lungs of an 

 animal with bovine tuberculosis resulted alwaj's in rapid illness, 

 ending often in death, while some w^ere killed in a miserably sick 

 condition after three months. In all cases there was extensive tu- 

 berculosis, involving the internal organs, especially tttie lungs and 

 Bpleen. 



