358 Annual Report for 1911 of Royal Veterinary College. 



presence of bacilli with the special characters of those occur- 

 ring in bovine lesions had failed. 



The great bulk of the work done by the Royal Commission 

 was designed to test the soundness of these arguments. 



At the outset the Commission devoted themselves to a 

 minute study of the characters of the bacilli found respectively 

 in cases of human consumption (which is the commonest form 

 of the disease in man) and in cases of tuberculosis in cattle. 

 The general result of this part of the work was to confirm one 

 of the premises contained in the second argument set out above, 

 viz., that the bacilli which are usually present in cases of 

 consumption in man differ in some respects from those found 

 in tuberculosis of the l)ovine species. These differences relate 

 to the appearance presented by artificial cultures of the bacilli 

 and the effects which they produce when animals of different 

 species are experimentally infected with them. The broad diff!er- 

 ence in the first of these i-e.spects is that when cultivated outside 

 the body the bacilli derived from tuberculous cattle grow more 

 slowly and less luxuriantly than those which are usually 

 present in cases of tuberculosis in man. The second difference 

 is that the bovine bacilli are decidedly more virulent than the 

 human when they are experimental!}' used to infect different 

 animals, such as the ox, rabbit, and pig. 



Without begging any of the question in dispute, it is there- 

 fore convenient to agree to call the bacilli found in the natural 

 disease of cattle the "bovine type" of tubercle bacilli, and the 

 bacilli which are more commonly present in tuberculosis of 

 man the " human type." 



This point having been settled, the next step in the investiga- 

 tions naturally was to proceed to examine the characters of the 

 Ijacilli present in a series of cases of human tuberculosis in 

 order to determine whether they were of the human or of the 

 bovine type. Obviously in this search for the bovine type in 

 human beings attention was first turned to cases in which the 

 disease appeared to have begun in connection with alimentary 

 tract (the lymphatic glands of the throat and neck, the intes- 

 tines, and the lymphatic glands of the abdomen), for if milk or 

 meat containing tubercle bacilli causes tuberculosis in man that 

 is where one would expect the disease to have its starting point. 

 The search in this direction soon showed that Koch was 

 mistaken in supposing that such cases were rare, for as a matter 

 of fact the Royal Commission had no difficulty in finding 

 cases of human tuberculosis in which the disease had begun in 

 connection with the parts mentioned above. 



Altogether the Royal Commission investigated thirty-eight 

 cases in which the situation of the disease appeared to justify 

 the inference that, whether the infecting liacilli were of the 



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