ENTRANCE OF TUBERCLE BACILLUS INTO MILK 239 



bacilli were detected on twenty occasions. One of the cows 

 constantly coughed up a tenacious mucus containing large numbers 

 of tubercle bacilli. During a period of time extending over forty- 

 three days mucus from two cows was collected and inoculated into 

 forty-five guinea-pigs, twenty-two of which, escaping peritonitis, 

 were available for post-mortem examination for tuberculosis. 

 Eleven, or fifty per cent, of them, were found to be markedly 

 tubercular.^ The saliva as well as the bronchial mucus of 

 tuberculous cows has been found to contain abundant bacilli, and 

 by licking her udder it is possible for a tuberculous cow to convey 

 tubercle bacilli to its exterior surface. 



The excreta also are infective when lesions are located in the 

 alimentary canal. In tuberculosis affecting the alimentary canal 

 of the cow (one per cent, of the cases), it is thus possible to get 

 contamination of the milk, indirectly, from the excreta. The 

 mucous membrane of the intestine, especially the colon, sometimes 

 shows tubercular ulcers, which are less frequently observed in the 

 abomasum. Tubercles may also develop under the mucous mem- 

 brane and serosa of the stomach and intestines. In these ways 

 arises a condition of intestinal tuberculosis, which in its acute or 

 ulcerating stage will cause the excreta to be loaded with tubercle 

 bacilli. Any one familiar with a cowshed will at once recognise 

 how readily milk might become infected under such circum- 

 stances, which, though undoubtedly exceptional, must not be 

 overlooked.- As we have seen, Cadeac and Bournay, Strauss 

 and Wurtz, and other investigators have shown that tuberculous 

 material is not rendered innocuous by the gastric juice, and 

 there is therefore no doubt that true virulent tubercle bacilli 

 can pass through the alimentary canal of the cow and be 

 found in manure, straw, and stable refuse. In these ways stalls 

 may become infected and transmit the disease to fresh herds 

 stabled in such premises. Nor are herds unstabled always free 

 from tuberculosis, as has been recently stated. A number of 

 observers have shown that whilst it is true that ill-ventilated, dark, 

 damp cowsheds predispose to infection, milch cows living entirely 

 in the open do not, on that account, escape the disease.^ It 



^ Commonwealth of Pennsylvania, Bulletin 75 (Pearson and Ravenel), 1901, 

 p. 82. 



- Trans. British Congress on Tuberculosis, iQoij vol. iii., p. 664 (Boinet and 

 Heron). 



3 Report on Bovine Tuberculosis, Government of New Zealand, 1900 

 (Gilruth). 



