376 Hydrophobia, Lyssa, or Rabies 



of the protozoan nature and etiological importance of these bodies, 

 they are tentatively accepted as the cause of the disease and treated 

 accordingly in the text. To these bodies Calkins has given the 

 name Neurorrhyctes hydrophobiae. 



Morphology. — By appropriately staining sections of the cerebrum,, 

 cerebellum, pons, basal gangha, spinal gangha, and sahvary glands, 

 of human beings or animals dead of rabies, it was possible to demon- 

 strate small rounded bodies measuring 4 to lo /i as a rule, though 

 var3dng from i to 20 ju, in the interior of the protoplasmic process of 

 the cells. In experimental infections they are most numerous in 

 the hippocampal convolution. The bodies, when stained by the 

 methods given below, usually appear red in color. They are ovoid 

 in shape, well-circumscribed, and vary in size from invisibility to 

 20 n in length. The smaller of them do not show any structural 

 differentiation, but the larger show central condensations that may 

 be nuclear material. The greater number of them he in the cyto- 

 plasm of the nerve cells; some are free. These are the Negri bodies. 



Williams and Lowden* are convinced that they are protozoan 

 organisms, that they are the cause of rabies, and that their presence 

 is pathognomonic of rabies. They believe: 



1. The smear method of examining the Negri bodies (vide infra) is superior 

 to any other method so far published for the following reasons: (a) It is simpler, 

 shorter and less expensive; (6) 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 as shown by the smears, as well as by the sections, 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 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 

 of the host tissues. 



5. Forms similar in structure and staining qualities to the others, but just 

 within the limits of visible structure (at 1500 diameter magnification), have been 

 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 morphology is constantly cyclic, i.e., certain forms always preponderate 

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

 and multiplication can be demonstrated; (c) the structure and staining quali- 

 ties, as shown especially by the smear method of examination, resemble those 

 of certain known Protozoa, notably of those belonging to the sub-order 

 Microsporidia. 



7. The proof that the Negri bodies are living organisms is sufficient proof 

 that they are the cause of hydrophobia; a single varifety of living organisms found 

 in such large numbers in every case of a disease, and only in that disease, appear- 

 ing at the time that the host tissue becomes infective, in regions that are infect- 

 ive, and increasing in those infective areas with the course of the disease can 

 be no other, according to our present views, than the cause of that disease. 



One of the objections urged against the bodies of Negri as the 

 specific cause of the disease was the failure of the organism to 



*"Jour. of Infectious Diseases," 1906, m, 452. 



