306 



THE PATHOGENIC RHIZOPODA 



With the exception of the rhizopods, the entire range of protozoa 

 offers no analogies to these stages of neuroryctes. The series of forms, 

 following more or less closely the clinical history, agrees with the his- 

 tory of the parasitic amebse so far as the general outline goes, while 

 further details and careful study are necessary before the life history 

 can be stated. With our present knowledge it appears that the organ- 

 ism, as seen in its smallest forms, is uninucleate; that as it develops 

 into a larger ameboid form, the nucleus, either by fragmentation 

 (as in polystomella) or by diffusion (as in centropyxis or Entameha 

 histolytica), gives rise to the diffused chromatin or idiochromidia. In 

 its mode of asexual reproduction it apparently follows Entameha 

 histolytica in binary fission and in budding. Its sexual reproduction 



Fig. 121 



"Negri bodies in nerve cells." (After Wolbach.) A X 2000; B X 1000. 



is as yet unknown, the union of two cells, as pictured by Williams and 

 Lowden, being quite unlike any authentic account of conjugation in 

 rhizopods or sporozoa. The nature of the "fixed"- form, also, is 

 enigmatical, but may be looked upon as a biological response on the 

 part of a highly variable organism to long-continued conditions of the 

 same nature. 



Further work is needed on Neuroryctes hydrophobioB in respect to 

 the mode of division and budding, and with especial reference to the 

 nuclear phenomena; further, in respect to the nature of the permanent 

 forms, encysted or otherwise, which might be expected to exist in 

 animals shortly after recovery from rabies ; and finally, work is needed 

 in connection with the sexual phenomena whereby the potential of 

 vitality of the parasite, and with it its capacity for further mischief, 

 is restored. 



The early illustrations published by Negri, Luzzani, and others of 

 the organism of rabies showed an irregular body with numerous 





