96 CLEAN MILK 



virulence in ordinary salted butter for four and a half months or 

 longer; in cheese, 30 or 40 days, (Schroeder & Cotton) and as 

 tubercle bacilli are found in about one-fourth of samples of separ- 

 ator slime the reasonable inference may be drawn that they occur 

 with the same frequency in the cream from which the butter is 

 made and therefore in 25 per cent, of butter. 



The danger of consuming milk from tuberculous cows is seen 

 more conspicuously in children. In 20 cases of primary tuberculosis 

 of the bowels and mesenteric glands, in children, 13 were caused by 

 the bovine germ of tuberculosis and 7 by the human type of the 

 tuberculosis germ. In 16 children with tuberculous glands of the 

 neck, 10 of the cases could be attributed to the human type of 

 tuberculosis germ and 6 to the bovine form. In 140 cases of tuber- 

 culosis in human beings, 21 or 15% were derived from a bovine 

 source (Steffenhagen). The distinction between tuberculosis germs 

 derived from bovine and human sources is made by studying the 

 characteristics of the germs during their growth outside the body 

 upon special culture media, and also by the injection of the germs, 

 into animals. The bovine bacillus of tuberculosis when injected into- 

 cattle and the lower animals is much more virulent than the human 

 type. 



Recent experiments from many sources (German Commission 

 and British Royal Commission on Tuberculosis, etc.) appear to 

 show that in tuberculosis of children respectively, 10 and 23 per 

 cent, of the cases are due to the tuberculosis germ peculiar to cattle 

 (Bovine tubercle bacilli), thus locating the origin of 10 to 23 per- 

 cent, of children's tuberculosis in milk. 



In the light of most recent scientific studies and experiments, 

 tuberculosis in man appears to start more frequently in the digestive 

 tract than was formerly supposed even when the disease is situated 

 only in the lungs and other parts of the body. No cow should be 

 placed in a herd until it has been tested and found free from tubercu- 

 losis. Such testing must be repeated once a year, or twice, if there: 



