TUBERCULOSIS 77 



man. In support of the latter statement, Koch produced 

 statistics which were said to prove the great inf requency 

 of man's infection with tuberculosis through food. 



It is evident that the question of the identity or non- 

 identity of tuberculosis of man and cattle is of great 

 importance in the control of the milk supply. Koch, con- 

 sequently, drew the conclusion from his investigations 

 that the control of meat and milk, so far as tuberculosis 

 is concerned, is superfluous and unnecessary. There- 

 fore, we have all the more reason for a closer consid- 

 eration of the three questions placed in the foreground 

 by Koch's report. 



1. Is tuberculosis from food infection rare in man? 



2. Can human tuberculosis be transmitted to cattle? 



3. Can it be proven that tuberculosis of cattle is 

 transmissible to man? 



If we first consider the question of the frequency of 

 the occurrence of tuberculosis in man from infection 

 through his food, it will be seen at once that differences 

 of opinion exist concerning the modes of infection. The 

 usual opinion (until quite recently) is that by far the 

 greatest number of cases of tuberculosis in man are 

 caused by inhaling the dry bacilli; there is, however, 

 opposition to this view. Ribbert and Aufrecht have 

 concluded that tuberculosis of the lungs is of embolic 

 origin and others (Grawitz) have found the tonsils to be 

 among the most favorable places for the admission of 

 bacilli. Observations on animals, particularly on swine 

 and monkeys, caution us not to draw definite conclusions 

 in relation to the mode of infection from the gross ana- 

 tomical lesions. Thus, for example, with swine that 

 are infected almost exclusively through the digestive 

 canal, tuberculosis of the intestines is an exception, 

 while miliary tuberculosis of the lungs often leads to a 

 rapidly developing caseous pneumonia. 



