368 BACTERIA IN INFECTIOUS DISEASES 



middle, resembling a figure 8, and of which the diameter 

 of each half often does not exceed a half a thousandth 

 of a millimeter. Each of these little particles is sur- 

 rounded at a certain focus with a sort of aureole which 

 corresponds, perhaps, to a material substance." 



The possibility that this appearance is due to 

 diffraction is considered, but Pasteur inclines to 

 the opinion that in the case in question it is due 

 to a mucous substance which surrounds the organ- 

 ism. (See Fig. 3, Plate VI.) 



At the meeting of the French Association for 

 the Advancement of Science, in 1881, Chauveau, 

 in his address as President of the Association, 

 says : " For a moment we hoped that Pasteur 

 had determined thus [by artificial cultivation] the 

 virus of hydrophobia, but he tells us himself that he 

 has only cultivated a new septic agent" Koch's recent 

 attack upon Pasteur, in which he makes much of 

 this mistake, seems a little out of place in view of 

 this frank confession made more than two years 



ago. 



The last-named observer has also encountered 

 this form of induced septicaemia in the rabbit, and 

 has shown that the micrococcus which produces it 

 is not alone found in human saliva. This was a 

 priori to have been expected, and the writer has 

 never supposed that the human mouth was the 

 only habitat of the micro-organism in question. 

 But being unwilling to generalize from insufficient 

 data, he has not even claimed that all human saliva 

 is fatal to rabbits, but has taken pains to say, in 



