CHANNELS OF INFECTION 317 



due to the same bacillus. The wording of the report is : 

 " Whatever, therefore, may be the animal source of tuber- 

 culosis in adolescents and in adult man, there can be no 

 doubt that a considerable proportion of the tuberculosis 

 affecting children is of bovine origin, more particularly 

 that which affects primarily the abdominal organs and 

 the cervical glands. And further, there can be no doubt 

 that primary abdominal tuberculosis, as well as tubercu- 

 losis of the cervical glands, is commonly due to ingestion 

 of tuberculous infective material. The evidence which 

 we have accumulated goes to demonstrate that a con- 

 siderable amount of the tuberculosis of childhood is to 

 be ascribed to infection with bacilli of the bovine type 

 transmitted to children in meals consisting largely of the 

 milk of the cow. 



" We are convinced that measures for securing the 

 prevention of ingestion of living bovine tubercle bacilli 

 with milk would greatly reduce the number of cases of 

 abdominal and cervical gland tuberculosis in children, 

 and that such measures should include the exclusion from 

 the food supply of the milk of the recognisably tuberculous 

 cow, irrespective of the site of the disease, whether in the 

 udder or in the internal organs." 



Eber, 1 in an extended investigation, succeeded in infect- 

 ing calves from three cases of human pulmonary tuber- 

 culosis. The bacilli isolated from the human material were 

 of the human type, but after passage through the calf 

 became transformed into the bovine type. He affirms, 

 therefore, the essential identity of the human and bovine 

 types of tubercle bacilli. 



With regard to the channel of infection in human tuber- 

 culosis opinions differ. Koch insisted that inhalation of 

 air- borne bacilli derived from dried human sputum is the 

 principal source of infection ; Von Behring, on the other 



1 Centr.f. BakL, Abt. I (Orig.), lix, 1911, p. 193. 



