540 Veterinary Medicine. 



1869, demonstrated the virulence on the lower animals of the milk 

 of infected cows, and many accidental infections have shown the 

 same for man. (See relation of the bacillus of man to that of 

 animals). This conceded, the question arose as to the virulence 

 of milk drawn from the sound udders of tuberculous cows. 

 Many experiments of Nocard, Galtier, McFadyean and others 

 seemed to decide against such infection. Others have had a dif- 

 ferent experience, and especially when the test was made by in- 

 oculation. Ernst found tubercle in 30 per cent, of the cows he 

 examined, though no affection of the udder could be made out. 

 Theobald Smith, Hirschberger, Bang and others found tubercle 

 bacilli in milk from sound udders. Pearson, inj ecting the milk from 

 sound udders intraperitoneally into Guinea pigs had ten in sixty- 

 three affected . Rabinowitsch and Kemper found tubercle bacilli in 

 milk, in ten out of fifteen cows with sound udders. While it must 

 be allowed that often a very small proportion of tuberculous cows 

 with sound udders pass the bacilli in the milk yet a sufficient 

 number of exceptions are found to deter one from endorsing such 

 milk as safe. Much more is this conclusion justified by the con- 

 sideration that commencing mammary tuberculosis is in many 

 cases unrecognizable by ordinary examination intravitam or post 

 mortem. Again when the bacilli are circulaiting in the blood 

 (generalized tuberculosis) they can escape from such a vascular 

 tissue as the mamma without the formation of a local lesion, as 

 they can pass through the intestinal walls or lungs and colonize 

 the adjacent lymph glands. Nocard's injections of the bacilli 

 into the veins seem to show that they disappear from the blood in 

 4 to 6 days, but with a generalization of the infection from within, 

 the presumption is against a single isolated entrance of bacilli, 

 and in favor of a continuous introduction. In such generaliza- 

 tion therefore the bacilli circulate in all vascular tissues, and are 

 liable to escape with any normal secretion, but especially with the 

 milk or urine on account of the great vascularity of the glands. 

 When the udder is itself tuberculous the case is incomparably 

 worse. The milk can scarcely fail to be infecting, and the bacilli, 

 grown in these highly vascular tissues, apart from the air, are 

 usually of a very virulent type. Of these Martin writes in the 

 report of the Royal Commission (Kngland) : " The milk of cows 

 with tuberculosis of the udder possesses a virulence which can 



