PROTOZOA 41T 



that dies of rabies. Negri bodies appear in smear and impres- 

 sion preparations and in sections of the brain. Ammon's horn 

 seems to be the most satisfactory part to examine for these 

 bodies. There is a very large literature on this subject. The 

 work of Williams and Lowden l indicates that these bodies 

 belong to the Protozoa. The following are their conclusions. 



''The smear method of examining the Negri bodies is su- 

 perior to any other method so far published for the following 

 reasons: (a) It is simpler, shorter, and less expensive; (b) 

 The Negri bodies appear much more distinct and character- 

 istic. For this reason and the preceding one, its value in di- 

 agnostic work is great; (c) The minute structure of the Negri 

 bodies can be demonstrated more clearly; (d) Characteristic 

 staining reactions are brought out. 



"The Negri bodies as shown by the smears as well as by 

 the sections are specific to hydrophobia. 



"Numerous 'bodies' are found in fixed virus. 



" ( Bodies' are found before the beginning of visible 

 symptoms i. e., in rabbits on the fourth day in fixed virus, 

 on the seventh day in street virus and evidence is given that 

 they may be found early enough to account for the appearance 

 of infectivity in the host tissues. 



' ' Forms similar in structure and staining qualities to the 

 others, but just within the limits of visible structure (at 

 1,500 diam. magnification) have been seen. Such tiny forms, 

 considering the evidence they give of plasticity, might be able 

 to pass the coarser Berkefeld filters. 



"The Negri bodies are organisms belonging to the class 

 protozoa. The reasons for this conclusion are: (a) They have 

 a definite, characteristic morphology; (b) This morphology is 

 constantly cyclic, i. e., certain forms always predominate in 

 certain stages of the disease, and a definite series of forms in- 

 dicating growth and multiplication can be demonstrated; (c) 

 The structure and staining qualities, as shown especially by 



1 Williams and Lowden. Jour, of Inf. Diseases, Vol. ill (1906) 

 p. 452. 



