464 RABIES 



conclusion relative to the nature and diagnostic value of the 

 Negri bodies are as follows : 



1. The smear method of examining the Negri bodies is 

 superior to any other method so far published for the follow- 

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

 The Negri bodies appear much more distinct and characteristic. 

 For this reason and the preceding one, its value in diagnostic 

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

 can be demonstrated more clearly ; (d) Characteristic staining 

 reactions are brought out. 



2. The Negri bodies are shown by the smears as well as 

 by the section are specific to hydrophobia. 



3. Numerous "bodies" are found in fixed virus. 



4. "Bodies" are found before the beginning of visible 

 symptoms — i. e., on the fourth da}' in fixed virus, on the 

 seventh day in street virus, and evidence is given that the}' 

 may be found early enough to account for the appearance of 

 infectivity in the host tissues. 



5. Forms similar in structure and staining qualities to 

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

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

 considering the evidence they give of plasticity, might be able 

 to pass the coarser Berkefeld filters. 



6. 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 morpho- 

 logy is constantly cyclic, i. e., certain forms always predomi- 

 nate in certain stages of the disease, and a definite series of 

 forms indicating growth and multiplication can be demon- 

 strated ; (c) The structure and staining qualities as shown 

 especially by the smear method of examination resembles that 

 of certain known Protozoa, notably of those belonging to the 

 sub-order Microsporidia. 



7. The proof that the "Negri bodies" are living organ- 

 isms is sufficient proof that they are the cause of hydrophobia ; 

 a single variety of living organisms found in such large num- 



