TUBERCULOSIS. 157 



another entirely different host under favorable circumstances. 



In living tissue the tubercle bacilli exercise a slow but 

 progressively destructive action through their constant prolif- 

 eration. Inoculation experiments on lower animals show a 

 wide degree of virulence in the bacilli, and the susceptibility 

 of different animals varies greatl)% some being easy to infect 

 and others showing great resisting powers. 



Not wishing to go into extensive and exhaustive discus- 

 sion pro and con, but believing firmly that Prof. Koch was 

 mistaken in his statement that animal tuberculosis was not 

 transmissible to man, I will (luote some authority and experi- 

 ments that go to show that he was at least a little hasty in 

 making such a statement. After the discovery of the tubercle 

 producing organism many scientists set to work to study its 

 nature and habits. One of the most noted of these to make 

 the study in a comparative way was Theobald Smith, who 

 after an elaborate, well planned and scientifically executed 

 research, which included not only the full description of the 

 morphology and cultural characteristics of the human and 

 bovine tubercle bacilli, but also parallel inoculation of five 

 species of animals, reached the conclusion that the disease 

 was not only transmissible from animal to animal, btut also 

 from man to animal. 



Some years having elapsed during these experiments, in 

 about 1 90 1 Prof. Koch made the startling announcement that 

 there was but little danger of man becoming infected from 

 tubercle bacilli of bovine origin, because the two were of dif- 

 ferent source and were not transmissible. He also stated that 

 the transmissibilit}' of tuberculosis from man to animal was 

 exceedingly improbable, if not impossible. These statements 

 coming from so good an authority created quite a stir, but 

 Koch's assertions were apparently the result of a comparison 

 of only the pathogenic effects of these bacilli on two species 

 of animals, while Smith's — as stated — were on numerous 

 specimens and five species of animals. 



The demands made by Smith can be performed and met 



