LIPE-CYOLE OF " CYSTOBIA " IRREGULARIS (mINCH.). 49 



complicated cliaracter that it is quite impossible to say to 

 which half any givcD lobe or portion belongs. As a rule a 

 very narrow space separates any two adjoining segments, but 

 sometimes this is not easy to make out ; in these cases the 

 nuclei help to define their limits. Tlie segments are very well 

 marked out by this means in fig. 55, which is a section through 

 such a stage in C. minchinii (one of the very few sporulating 

 cysts of this species that I have come across). Here the 

 nuclei are unusually numerous and close together, and nearly 

 everywhere in paired rows, each row belonging to a different 

 lobe and, in all probability, to a different associate. In 

 fig. 44 e a small region at the periphery of the cyst is seen 

 highly magnified, and shows a portion of two lobes with the 

 narrow space {sp.) between. All along the margin of each 

 segment are arranged the sexual (sporoblast-) nuclei.^ 



Segregation of the sporoblasts. — The later develop- 

 ment of the sporoblasts follows a slightly different course 

 from that generally described in the case of other Gregarines. 

 When the lobes and processes are fully developed and com- 

 pletely intermingled the sporoblast-nuclei throughout the 

 cyst take up a position of equal distribution, each being 

 surrounded by about the same area of cytoplasm. In a low- 

 power view (fig. 53 a) they appear, in any section, evenly 

 arranged throughout the mass and no longer define the limits 

 of the segments, the outlines of which have ceased to be dis- 

 tinct. A poriion of the cytoplasm next becomes segregated 

 around each nucleus, simply by the appearance of narrow, 

 irregular spaces which sufl&ciently divide up the whole. 

 Practically the entire cytoplasm is thus used up-; in other 

 words, there is no large cystal residue or " gregarinoid 

 soma " left over in the cyst. I can say this with absolute 



1 Neither this section nor that of C. irregularis in fig. 56, both of which 

 were stained with thiouin and orange, shows the chromatoid granules in the 

 cytoplasm, as tiiionin is soon extracted from tliem ; for this reason, in fact, I 

 occasionally used it, since iroii-liseniatoxylin stains them so intensely that the 

 nuclei themselves tend to be obscured. 



- See below, p. 54', for instances of what are, probably, abnormal exceptions. 

 VOL. 50, I'AliT 1. NEW SERIES. 4 



