NON-SPORING BACILLI 277 



until sent to be slaughtered. Apart from that, however, 

 the figures suggest the influence of open-air life in 

 lowering the susceptibility of the sheep and the chances 

 of infection. 



B. tuberculosis of the human type is pathogenic for 

 guinea-pigs, less so for rabbits, and still less so for 

 dogs. 



B. tuberculosis of the bovine type is very pathogenic for 

 guinea-pigs, killing them more quickly and producing 

 more extensive lesions than the human type ; while 

 intravenous injection in rabbits causes an acute tuber- 

 culosis with death in from two to five weeks ; the 

 human type causing a mild, slow disease, usually lasting 

 for six months, and at times failing to kill the rabbit. 

 This is the readiest method of distinguishing these 

 two types. 



The human type is found in the majority of human 

 infections (46 out of 60 investigated), never in bovine 

 tuberculosis. 



The bovine type is found always in bovine tuberculosis, 

 and in a considerable number of cases of human tuber- 

 culosis (14 out of 60 = 23 per cent), and in all the latter 

 but one, the lesions were of the cervical lymphatic glands, 

 or were lesions of primary abdominal tuberculosis, that 

 is, were lesions which might fairly be attributed to feeding 

 or alimentation. Moreover they were mostly in children, 

 so that the deduction is made that bovine tuberculosis is 

 transmissible to man, the milk of tuberculous cows being 

 the usual vehicle. 



Bovine tubercle bacilli, in cultures, are shorter, thicker, 

 and more regular in size than the human type, and their 

 growth on the various media is scantier. They are more 

 pathogenic to cattle and swine, and less so to man, which 

 may explain the chronicity of abdominal and cervical 

 glandular tuberculosis. 



A recent research by Park and Krumwiede confirms the 

 results of previous investigations. They state that com- 

 parative luxuriance or sparseness of growth is in most 

 cases absolutelv to be relied on for differentiation. 



