466 Rabies. 



sometimes very small, marginal, and, at other times, largier, central 

 formations (small and large inner formations) seem to be imbedded, 

 which contain very fine ring, rod or dumb-bell-shaped inclosures. The 

 rod-shaped bodies contain a fine granule sometimes at one or both ends, 

 while the ring-shaped bodies show one or more similai* chromophile 

 granules around a light central space. 



This complicated Structure at once excludes the characterization 

 of Negri bodies as products of degeneration; besides, their specificity 

 is demonstrated by the fact that they are only found in rabid animals. 

 There is, however, a doubt as to their parasitic nature and their im- 

 portance as the exciting agent of rabies. The filterability of the virus 

 and the fact that in the initial stage of the disease and in animals 

 infected with fixed virus, Negri bodies are generally lacking seem 

 to speak against it, but still the possibility exists that the true specific 

 virus consists of small formations, barely visible or completely invisible, 

 which develop only in the nervous system of the infected animals, 

 and aided by the cell reaction, first form small and simple corpuscles 

 and later large, complicated bodies (Di Vestea, Volpiho). 



Negri has recently confirmed his conception of the bodies named for him as 

 true rabies parasites by microscopic discoveries according to which the formations 

 at a certain stage of evolution contain a nucleus in a homogeneous original substance, 

 which breaks up into very diminutive chromatin granules, whereupon the surround- 

 ing plasma is divided. In this way small corpuscles are formed which consist of 

 a chromatin granule and its capsule, and later grow up to new independent bodies. 

 Quite consistent with this conception are discoveries by Babes, Koch, and Eissling, 

 who in sections of the cornu ammonis, but mainly in the degenerated ganglion cdlls 

 stained according to Oajial, Giemsa or Heidenhain, have found cocci-like formations 

 in large number, scarcely 1 /t. in size, surrounded by a light capsule. They are 

 of the opinion that these formations are the active causative agents of rabies, 

 while the Negri bodies which inclose them are reaction products of the ganglion 

 cells produced by their irritation. 



Prowazek considers the capsulated small formations as protozoa and designates 

 them as chlamydozoae, the same as the causal factors of vaccinia, chicken pest, etc. 

 In favor of their protozoan character and against their bacterial nature is the fact 

 that rabies virus is injured by gall and glycoside (Frantzius, Kraus, Eisler, LeBieur), 

 which substances are known to be poisonous to prdtozoa and cells, but are ndt 

 poisonous for bacteria. 



Finally, the specificity of the Negri body is also shown by the fact that its 

 abundance is in direct proportion to the virulence of the same parts of the nervous 

 system. According to Fermi the order of sequence is cornu ammonis, cortex cerebri, 

 medulla oblongata and spinalis; then, cerebellum, thalamus opticus, and nucleus 

 caudatus. 



Very small bodies from 0.5-2.0 /i. in size, were also found by Bertarelli, 

 Febre and Bonnard in the brains of dogs inoculated with fixed virus, and by 

 Lentz and Manqueliau in rabbits treated in the same way. Their absence or the 

 fact that they could not be found may have some connection with the knowledge 

 that this form of the disease has such a brief course that no larger formations 

 are developed. Schiffmann found by frequent passages that first the complex, and 

 then the single, smaller bodies disappear from the cornu ammonis. Lentz describes 

 as ' ' rabies corpuscles of passage ' ' the Negri-like formations which are larger' in 

 size and also contain larger, compact, inner corpuscles, and besides are freqtletttly 

 located extracellularly. They come from nuclei or ganglion cells under simultatieous 

 disintegration of the protoplasm. 



Tenacity. The medulla oblongata of rabid animals retains its virulence for 

 months at ordinary room temperature when protected from drying and putrefaction 

 (Pasteur, Frothiijgham) ; on the other hand the spinal cord of rabbits becomes 

 non-virulent in 14 or 15 days when exposed in a dry, dust-free atmosphere (Pasteuf) 

 or in 4 or 5 diys if spread in a thin layer (Galtier). Fluid saliva infects even 

 after 24 hours (Gibier) ; dried saliva not later than 14 hours (Celli). The virus 

 is destroyed in one half hour at 52°-58° C. (Hogyes), and in two minutes at 



