NEUROSFORIDIUM. 95 



differeutiatecl protoplasm ; each pansporoblast becomes a 

 spore-morula, dividing into about a dozen small, round, uni- 

 nucleate spores. In these respects Rhinosporidium 

 resembles Neurosporidium. In Rhinosporidium, how- 

 ever, there is a well-defined cyst secreted by the parasite, 

 and the outline of the spore-morula is rather more distinct, 

 there being a definite membrane round each, and the outline 

 of each spore in a full-grown spore-morula is also well marked. 

 This slight difference in the definiteness of contours is of 

 little importance as compared with the segmentation of pan- 

 sporoblasts into many spores, which is in marked contrast 

 with what occurs in the typical Haplosporidia. 



Neurosporidium differs also from Rhinosporidium 

 in that the spore-formation from pansporoblasts is not pro- 

 gressive, as it is in the latter. In Rhinosporidium the 

 pansporoblasts, within a large cyst, are disposed in three 

 zones, merging the one into the other, namely, a peripheral 

 zone of uninucleate pansporoblasts just within a thin layer of 

 undifferentiated protoplasm, an intermediate zone of pan- 

 sporoblasts with two or three nuclei each, in which zone 

 spore-formation is proceeding, and a central mass in which 

 each pansporoblast, now a spore-morula, contains about a 

 dozen uninucleate spores. In other words, spore-formation 

 proceeds in a centrifugal direction within the cyst, the central 

 pansporoblasts completing their sporulation before the peri- 

 pheral ones begin to divide. 



In Neurosporidium, on the other hand, there is an 

 interval between the simultaneous formation of the uninucleate 

 pansporoblasts and their segmentation, and the segmentation 

 of the spore-morulae occurs simultaneously throughout the 

 same capsule. 



As pointed out by Minchin and Fantham,^ Rhinospori- 

 dium, in the successive formation of its pansporoblasts, 

 resembles Schewiakoff's parasite of the Cyclopidse," to which 



' Loc. cit., p. 529. 



- ScliewiakofF, W., "Ueber einige ekto- uiid ento-parasitisclie Protozoen der 

 Cyclopiden," 'Bull. Soc. Imp. Nat. Moscou,' u. s., vii, 1893, pp. 1—29, pi. 1. 



