BACILLUS OF TUBERCULOSIS. 283 
Infection by Ingestion of Milk and Meat. Phthisi- 
cal sputum, however, is not held responsible for the 
occurrence of all human tuberculosis. Milk also 
serves as a conveyer of infection, whether it be the milk 
of nursing mothers suffering from consumption or the 
milk of tuberculous cows. The transmission of tubercle 
bacilli in the milk of tuberculous individuals has only 
been indirectly established in human beings, but in 
cow’s milk it has been abundantly proved. Formerly 
it was thought that in order to produce infection by 
milk there must be local tubercular affection of the 
udder; but it is known now that tubercle bacilli may 
- be found in the milk when an internal organ is infected 
and when careful search fails to detect any udder dis- 
ease. So that the milk of every cow which has any 
internal tubercular infection must be considered as pos- 
sibly containing tubercle bacilli. Rabinowitsch and 
Kempner proved beyond all question that not only the 
milk of tubercular cattle which showed no appreciable 
udder disease, but also those in which tuberculosis was 
only detected through tuberculin, frequently contained 
tubercle bacilli. Different observers have found tubercle 
bacilli in the milk of from 20 to 60 per cent. of tuber- 
culous cows. When we consider the prevalence of tuber- 
culosis among cattle we can readily realize, if the 
bovine bacillus readily infects human beings, the 
danger to which children are exposed from this source 
of infection. Thus, taking the abattoir statistics of 
various countries, we find that in Prussia 8.3 per cent. 
of the cattle slaughtered were tuberculous; in Dresden, | 
14.4 per cent.; in London, 25 per cent.; in Berlin, 12 
per cent.; in New York, about 7 per cent. Another 
possible source of infection in intestinal tuberculosis is 
