434 DISEASES OF CATTLE. 



increasing in virulence and approaching the activity of the bovine 

 bacillus, or are they really bovine bacilli which have multiplied in 

 the human body until their virulence has become attenuated? In 

 whatever manner these questions are decided it would seem that the 

 findings of the German commission, instead of supporting Koch's 

 views that we can decide with certainty by the inoculation of cattle 

 as to the source of any given bacillus, really show that this method 

 of diagnosis is extremely uncertain in the present condition of our 

 knowledge. 



It is definitely admitted that 4 of the human cultures caused gen- 

 eralized tuberculosis in cattle ; Kossel suggest, however, that it may be 

 possible that the bacilli in cases of human tuberculosis under certain 

 circumstances can likewise attain a very high pathogenic activity 

 for cattle without being for that reason bovine bacilli. Undoubtedly 

 the German commission is confronting the two horns of a dilemma, 

 either one of which is fatal to the views of Koch as stated with such 

 positiveness at London. If we accept this suggestion thrown out by 

 Kossel, we must conclude that Koch was wrong in his claim that 

 human tuberculosis can not be transmitted to cattle, and thus with 

 one blow we destroy the entire experimental support which he had 

 for his argument before the British Congress on Tuberculosis. If, 

 on the other hand, we accept the conclusion which follows from 

 the principle laid down by Koch for the discrimination between 

 human and bovine bacilli, and which appears to be favored by Kossel, 

 we must admit that bovine tuberculosis is an extremely important 

 factor in the etiology of human tuberculosis. Of the 39 cases of 

 human tuberculosis tested, 4, or more than 10 per cent, were virulent 

 for cattle and would be classified as of bovine origin ; however, these 

 4 cases, were all found among the 16 cases of tuberculosis in children 

 which the commission investigated ; hence it is plain that 25 per cent 

 of the cases tested of tuberculosis in children would by Koch's method 

 be classified as of bovine origin. 



In the Bureau of Animal Industry two distinct lines of experi- 

 ments have been carried on, in order that one might serve as a 

 check against the other. There has been, however, no discrepancy 

 in the results. De Schweinitz, in the Biochemic Division, Bureau 

 of Animal Industry, isolated 9 cultures from human tuberculosis. 

 Two were derived from human sputum, 3 from cases of generalized 

 tuberculosis in adults, and 4 from cases of generalized tuberculosis 

 in children. B}^ comparing these cultures with a newly isolated 

 virulent culture of bovine tuberculosis, there were found among 

 them 2 cultures from children which were identical in their cul- 

 tural and morphological characters with the bovine bacillus. These 

 cultures also killed rabbits and guinea pigs in as short a time as 

 did the bovine bacillus. Hogs which were inoculated subcutane- 



