BOVINE TUBERCULOSIS 167 



thought that, possibly, the danger of transmission from one to 

 the other has been overestimated. But that such transmission 

 is possible, especially from cattle to man, there seems to be 

 abundant and reliable evidence, and this possibility should 

 not be overlooked. 



How 7nay it be transmitted fro7n cattle to 7)2an? While it 

 seems possible that persons might become infected by inhaling 

 the dust of a tuberculous stable, there is very little direct evi- 

 dence of its occurrence. Man and cattle are so ^enerallv 

 exposed to infection from their own kind througii the medium 

 of the air, that it would be very difficult to trace it with cer- 

 tainty from one to the other. The danger of transmission by 

 the use of the flesh of tuberculous animals for food is, 

 probably, not great. The bacilli and tubercles rarely invade 

 the muscles, and are not often found in the blood. The flesh 

 might be contaminated from the diseased internal organs during 

 the process of slaughtering, or might inclose a small diseased 

 gland ; but such meat if well cooked would be free from dan- 

 ger. Heat sufficient for cooking is destructive to the bacilli. 

 There remains to be considered the milk. If the udder is 

 affected, the milk will in all probability contain the bacilli and 

 there is good evidence that the milk of tuberculous animals 

 may contain them even when there is no disease of the udder 

 discoverable. Such milk is therefore to be looked upon as 

 dangerous when used as food, especially by children. By far 

 the greater number of cases of human tuberculosis, for the 

 oriofin of which in infected milk the evidence seems to be con- 

 elusive, are those of children. This is so, doubtless, botii on 

 account of the comparatively greater quantity used, and the 

 inferior resisting power of the child's system. 



Milk concerning which there is any doubt may be rendered 

 safe for food, as far as the germs of tuberculosis are concerned, 

 by pasteurizing by heating at a temperature of 155° Fahren- 

 heit for twenty minutes. 



It may not be out of place here to call attention to the most 

 common means of the transmission of tuberculosis from man 

 to man, namely, by the sputum. The sputum of tuberculous 

 persons is likely to contain the bacilli, often in great numbers; 

 this is too often carelessly expectorated about the house, in 



