MILK-BORNE DISEASES 129 



an important and far-reaching influence in many 

 directions, but in nothing quite so noteworthy as 

 the effect produced upon Professor Koch. Follow- 

 ing Smith, Koch developed the comparative study 

 of the different types of tubercle bacilli, and in 1901, 

 at the British Congress on Tuberculosis, he made 

 an announcement which created a great sensation 

 in medical circles. With sweeping and startling 

 emphasis, he declared the tuberculosis of man and 

 the tuberculosis of animals to be different diseases; 

 that it is impossible to transmit human tubercu- 

 losis to cattle, and, that, consequently, man need 

 not fear infection from cattle, either by inhalation or 

 ingestion through eating tubercular meat or drinking 

 tubercular milk." It was in consequence of the 

 sensation produced by this memorable utterance 

 that the Royal Commission on the subject was ap- 

 pointed soon after the Congress closed. 



IV 



The sensation which the sweeping, optimistic 

 declaration of Professor Koch created will be under- 

 stood best by those who are familiar with certain 

 earlier experiments in the inoculation of animals of 

 different species, made by the same great teacher 

 and pointing to a radically different conclusion. 

 Chaveau, in 1868, had taken cattle from the Jura 

 Mountains, where tuberculosis among cattle seems 



