338 TUBERCULOSIS AS A TYPE OF BACTERIAL DISEASE 



obliterated. Bovine cultures are more difficult to isolate than human, 

 are apt to grow as discrete colonies in the first culture, and for 

 several generations grow in a thin layer which somewhat resembles 

 ground glass. The optimum temperature and the thermal death- 

 point are practically the same in both forms. 



The human bacillus, as a rule, grows somewhat more easily and 

 abundantly from the first, and will grow well on glycerine agar in 

 sub-cultures made directly from the original growth on blood serum. 

 All attempts to obtain a like result with the bovine organisms have 

 failed. In artificial culture the human bacillus rapidly loses viru- 

 lence. The bovine bacillus grows as a film on blood serum, whereas 

 the human bacillus produces warty growths. 



The morphological distinctions tend to disappear also in the 

 tissues of susceptible animals. We may inoculate a typical bovine 

 culture, and in a short time obtain from the various organs long and 

 much beaded bacilli simulating the human variety (Hueppe). 



The most striking dissimilarity is, however, seen in the action of 

 the bacilli from the two sources on animals. By whatever method 

 of inoculation, the bovine bacillus, as a rule, possesses a much 

 greater pathogenic power than the human bacillus for all animals on 

 which it has been tried (Villemin, Eavenel, and others), the only 

 exceptions being possibly those animals, like guinea-pigs, which are 

 so extremely susceptible to both types that it is difficult to draw very 

 much distinction between them. Dorset and other workers hold 

 that in bovine and human tuberculosis we have to do with organisms 

 differing usually in virulence, but between which there is no other 

 essential distinction.* 



Intercommunicability of Human and Bovine Tuberculosis 



Since the discovery by Koch in 1882 of the tubercle bacillus, it 

 has generally been held that tuberculosis in man and animals is one 

 and the same disease, f Villemin (1865) was the first to main- 

 tain this identity on the results of inoculation of bovine and 

 human tubercular matter into small animals. Chauveau (1868) 

 carried out similar experiments upon cattle.J Both workers 

 were successful in transmitting the disease, which produced similar 

 effects in the inoculated animals. Many other workers have 

 obtained like results, which were more or less uniformly in support 

 of the view that the identity of bovine and human tuberculosis was 



* Trans. British Congress on Tuberculosis, 1901, vol. iii., pp. 553-81. See also 

 experiment of Kossel and others, to which reference is made on p. 344, and 

 U.S. Dep. of Agriculture, 1904, Bull. 52 (Dorset). 



t Kruse, Pansini, Fischel, Johne, etc. See also Twelfth and Thirteenth Annual 

 Reports of the Bureau of Animal Industry, Washington, 1895-96 (Theobald Smith). 



Congrespour Vttude de la Tuberculose, Paris, 1888. 



