THE VIRUS OF HYDROPHOBIA 515 



their cytoplasm stains blue and the granules a blue-red, by 

 Mallory's stain the cytoplasm is magenta and the granules a 

 deep blue. The cytoplasm is homogeneous, and in it is a 

 nucleus -like body whose chromatin particles in the larger 

 individuals are arranged round the periphery, there being a 

 clear centre containing a nucleolus ; in the smaller forms the 

 nucleus is a mere chromatin spot. Round the central definite 

 nuclear body are some chromatoid particles which are irregular 

 in outline and size, are sometimes elongated, and do not take 

 on such a pure chromatin stain as the nucleus. There is 

 evidence of division of the nucleus, and sometimes there may 

 apparently be three or four nuclei in one body without division 

 of the protoplasm having occurred. Sometimes the chromatin 

 appears to fragment and break up into a large number of small 

 particles, and in such bodies active budding of the protoplasm 

 may be seen. Sometimes the bodies seem to go on dividing 

 again and again, with the result that some very small forms may 

 be produced, these sometimes appearing in mulberry masses. 



The Negri bodies have been found in nearly all cases of 

 street-rabies examined by many observers, and have never been 

 found in other conditions of brain disease. They occur in all 

 parts of the central nervous system, but are said to be most 

 abundant in the cells of the cornu Ammonis. They are 

 apparently not so readily found, at least in their larger forms, 

 in animals dying from the inoculation of virus fixe. What the 

 significance of these bodies is, it is at present, impossible to say ; 

 but whatever may be their nature, there is now considerable 

 evidence that their presence is specific of rabies, and that thus 

 in their recognition a much quicker means of diagnosis is possible 

 than by the longer method of awaiting symptoms in an in- 

 oculated rabbit. Many have looked on these bodies as protozoa, 

 and their appearance is not inconsistent with such a view. . The 

 objection which has been raised, that if they were protozoa 

 they could not pass through a porcelain filter (vide infra) as 

 the virus does, is met by the fact of the occurrence of minute 

 forms, and by the fact that similar small forms probably exist 

 in certain trypanosomes (see Appendix E). The occurrence of 

 minute forms would also account for the non-recognition of the 

 parasite in the more acute forms of the disease where there had 

 been an active vegetative condition, and thus no time for the 

 larger forms to develop. 



There is no doubt that between rabies and the bacterial 

 diseases we have studied there are at every point analogies, the 

 most striking being the protective inoculation methods which 



