DISEASES CAUSED BY INFECTS 9 



probably causes one fifth to a fourth of the tuberculosis 

 of infancy and childhood. 



It thus becomes evident, from the results which have 

 been briefly outlined here, that the bovine type of tubercle 

 bacillus plays a significant part in the etiology of tuber- 

 culosis in children, and that the effort to prevent this dis- 

 ease clearly must include the bovine sources. 



Bovine tuberculosis in man is practically always inges- j 

 tion tuberculosis; that is, the infection is taken into the 

 mouth, passes through the digestive tract, and invades 

 the glands and tissues of the body. We now know that the 

 tubercle bacillus may pass through the mucous membrane 

 without leaving a trail behind it. 



That, however, there is another side to this much dis- 

 cussed question is evidenced by the recent observations in 

 Germany. The Imperial Board of Health of Germany has 

 made observations to determine just how much danger 

 there is in drinking milk containing bovine tubercle 

 bacilli. The milk coming from all known cases of udder 

 tuberculosis was traced to the consumer and all the persons 

 drinking such milk or using fresh milk products from in- 

 fected sources were examined with reference to tuberculo- 

 sis. In all, one hundred and thirteen separate investiga- 

 tions were made, including six hundred and twenty-eight 

 persons (two hundred and eighty-four of whom were child- 

 ren, three hundred and thirty-five were adults, and nine 

 of unstated age), all of whom had undoubted opportun- 

 ities of consuming milk or fresh milk products from 

 cows having tuberculosis of the udder. The evidence pre- 

 sented is not equally valuable in each investigation. In 

 forty-four of the one hundred and thirteen investigations 

 cited, the milk was either heated, used in coffee or tea, 

 or mixed with milk from apparently tuberculosis-free cows 

 before it was consumed. 



Three hundred and sixty persons (of whom one hundred 

 and fifty-one were children, two hundred adults, and 



