300 PUBLIC HEALTH BACTERIOLOGY 



In other words, guinea-pigs, chimpanzees, and monkeys 

 are all highly susceptible to the effects of human or bovine 

 tubercle bacillus ; and the diseases produced in these 

 animals by both types are histologically and anatomically 

 identical. 



In man, experiment is not permissible, and no oppor- 

 tunity has offered of generalized disease set up by accidental 

 infection with the bovine tubercle bacillus. Nevertheless 

 many cases of fatal tuberculosis caused by the bovine 

 tubercle bacillus and nothing else have been investigated. 

 Compared with parallel cases caused by the human tubercle 

 bacillus, the two groups of cases were alike in their clinical 

 histories and their fatal termination, and were indis- 

 tinguishable anatomically when the lesions were examined 

 after death. Man must therefore be added to the list of 

 animals notably susceptible to bovine tubercle bacilli. 



Are these two types, then, varieties of the same organism ? 

 This is the conclusion, in spite of the failure to transmute 

 the one into the other. And, as a corollary, the lesions 

 they produce, whether in man or in other mammals, are 

 manifestations of the same disease. Whatever difference 

 of opinion may be held on this conclusion, in a considerable 

 proportion of cases of human tuberculosis the disease is 

 one and the same as bovine tuberculosis, being caused by 

 bacilli which are in every respect indistinguishable from 

 the bacilli which are the cause of tuberculosis in cattle. 

 In all such cases therefore the disease must unquestionably 

 be pronounced as one and the same. 



As regards avian tuberculosis, there does not appear to 

 be sufficient evidence at present to answer the question in 

 the affirmative. 



2. The conclusion reached is that, excluding the fowl 

 and other birds, mammals and man can be reciprocally 

 infected with tuberculosis. The transmission to man has 

 been conclusively shown by the study of fatal cases of 

 tuberculosis, mostly in children ; and from man to 

 mammals, by feeding experiments. 



3. Conclusions : 



(i.) Unmodified avian tubercle bacillus is a negligible 

 factor in the production of human tuberculosis. 



(ii.) It cannot be affirmed with confidence that man is 



