128 TUBERCULOSIS 



The stud}' of the lesions themselves gave rise to a number 

 of beliefs concerning their nature. Thus Virchow, Schiippel 

 and others declared that the tubercles in cattle were Ij'mpho- 

 sarcomata. Leisering considered them simplj' as sarcomata. 

 Spinola and Haubner maintained that human and bovine 

 tuberculosis were identical. 



In 1865, Villemin showed that tuberculosis was due to a 

 specific infection. He produced the disease in rabbits by in- 

 oculating them with tuberculous material from human sub- 

 jects. He also produced the disease by feeding experimental 

 animals and by causing them to inhale tuberculous material. 

 Chauveau, in the same year, produced the disease in cows. 

 These results were soon confirmed b}' Klebs, Cohnheim and 

 Gerlach. These experiments in which the disease was pro- 

 duced in one species with tuberculous material from another 

 followed by the discovery by Koch of the specific bacterium of 

 the disease, led to the view that tuberculosis in all species of 

 mammals was identical. This generally accepted belief caused 

 sanitarians to look upon tuberculosis in cattle as a great 

 menace to public health with the result that during the closing 

 decade of the last century, this disease in cattle was treated 

 more vigorously as a menace to the human species than as a 

 destructive disease of animals. 



In i8g6. Dr. Theobald Smith pointed out the fact that for 

 certain animals the tubercle bacteria from cattle were more 

 virulent than those from man and further, that there were cer- 

 tain morphological and cultural differences existing between 

 them. In 1S98, he published the results of a more extended 

 series of investigations. Since that time a number of investi- 

 gators have arrived at the same conclusion. The fact has 

 come to be well known that certain differences exist between 

 the bacteria of tuberculosis found in the human and in the 

 bovine species. Koch's experiments reported at the tubercu- 

 losis congress in London in July 1901, give additional evi- 

 dence of a difference in virulence for experimental animals of 

 the bacteria of human and of bovine tuberculosis. To what 

 extent the human species becomes infected from the bovine 

 kind cannot be stated, but the accumulating evidence tends to 



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