THE VIRUS OF HYDROPHOBIA 617 



singly or in clumps (kleine Innenformationen). With the eosin 

 dyes named above, and magnifications of 800 to 1000, the 

 smaller bodies appear a homogeneous reddish pink, and in the 

 larger bodies the outlines of the larger internal formations can 

 be recognised (see Plate). With Mallory's stain they present 

 similar appearances with a bluish stippling of the protoplasm. 



The Negri bodies have been found in practically 98 per cent, 

 of cases of street rabies in dogs examined by many observers in 

 different parts of the world. They are «also found in natural 

 rabies in other animals, and are usually present in human cases. 

 Numerous control observations on other toxic conditions of the 

 nervous system, especially where these are characterised by 

 spasms, have been made, and although occasionally, . e.g., in 

 tetanus, a somewhat similar appearance has been seen, at present 

 the consensus of opipion is in favour of an experienced observer 

 being able to recognise the Negri bodies as a specific appearance 

 in nerve cells. The bodies occur in all parts of the nervous 

 system, but are most common in the Purkinje cells of the cere- 

 bellum, and especially in the cells of the cornu Ammonis 

 (hippocampus major). It is in the last situation, therefore, that 

 they are generally looked for. They are apparently not so 

 readily found, and at any rate the larger forms may be altogether 

 absent, in animals dying from inoculation with the exalted fixed 

 virus. Hitherto they have not been certainly found in the 

 salivary glands or saliva of a rabid animal: 



While there is a general tendency to recognise the Negri 

 bodies as being specific to rabies, great difference of opinion 

 exists as to their true nature and as to their possessing any 

 etiological significance in the disease. Negri himself looks upon 

 them as protozoa, and the organism has been named by Calkins 

 newroryeteg hydrophobic. The chief arguments advanced in 

 favour of this position have been the constancy of the occurrence 

 of the bodies in the brains of animals suffering from the natural 

 disease, and their peculiar structure which, such authorities as 

 Golgi state, does not correspond to any cellular degeneration. 

 Against their protozoal nature has been urged their absence 

 from the virulent brains of animals dying from fixed virus, their 

 non-discovery in the infected saliva, and the fact that the virus 

 can pass through a coarse filter. These objections have been met 

 with the argument that the smaller internal formations may be 

 the infective agent in its essential form, and a modification of 

 this view is that the Negri body is a cellular reaction against 

 an invasion with these ultimate forms (see p. 622). .The whole 

 question must be looked upon as sub jvdice. 



