BOVINE TUBERCULOSIS 141 



ceptional cases transmitted from mother to foetus ; the predisposition 

 to receive and develop the germ is, however, hereditary. Infection 

 rarely takes place while diseased and healthy cattle are pastured 

 together in the open. Nocard and other observers frequently point 

 to the fact of the animals being infected while standing in stalls 

 adjacent to the coughing ' piner,' the disease often extending along 

 one side of the byre, while the cows on the other side may remain 

 sound, and it is also observed that the animals longest stabled furnish 

 the largest proportion of cases. While the author was Inspector for 

 the city and county of San Francisco, the tubercular seizures, with a 

 few exceptions, were all dairy cows, tubercular lesions in range cattle 

 being hardly ever observed. 



Nocard is against the total seizure of the carcases of cattle which 

 have localized tuberculosis, but are otherwise in good condition. He 

 insists that the bacilli of Koch, the true infectious material, does not 

 exist either in the blood or in the muscles, excepting for very brief 

 periods, and in cases of advanced general tuberculosis. In some of 

 Nocard's experiments with meat from cases of generalized tuberculosis, 

 he found that although it had no bad effects when eaten, the ex- 

 pressed juice produced tuberculosis in one or two of the guinea-pigs 

 when injected into the peritoneum. It is generally admitted that 

 the milk of tuberculous cows is greatly more liable than their flesh to 

 produce human tuberculosis. That this is so is very conclusively 

 proved by the fact that abdominal tubercle is practically confined to 

 children under five years whose food consists very largely of raw milk, 

 while the incidence is greatest in cases of infants hand-fed. Nothing 

 except milk infection can account for the terrible prevalence among 

 children of tabes mesenterica and allied tubercular disease. The 

 milk is not, however, always virulent. It is only so when the udder 

 is infiltrated with tubercular nodules. Nocard states that in his 

 experience he never found the milk virulent when the udder was free 

 from tuberculous lesions, and out of fifty -four cows seized for general 

 tuberculosis which he specially examined, only three had tubercular 

 lesions in the udder. At Copenhagen the proportion is still lower. 

 Bang estimates it at less than 3 per cent, of the number of tuber- 

 culous cows. However, the difficulty of deciding as to the non- 

 existence of tubercle in the mammary gland justifies the milk from 

 suspicious cases being excluded from consumption. (For the special 

 methods of examining and staining tubercle bacilli in milk, see 

 Technique, 20.) 



The question of living tubercle bacilli existing in ordinary market 

 butter has led to considerable investigation since Obermuller stated 



