34 H. M. WOODCOCK. 



nucleus, as Siedlecki found in Eucoccidium,^ and as also 

 occurs in Cystobia. In the nucleus of tlie ripe sporont 

 shown in fig. 36, for example, notwithstanding its large size, 

 the chromatic reticulum is, if anything, denser and more 

 marked than in the case of younger nuclei, which still have 

 large vacuoles in their karyosoraes (cf. figs. 19, 34, and 35). 



In conclusion, I regard the contents of the vacuoles in the 

 karyosome of Cystobia as also containing chromatin, but in 

 a more liquid or ''' storage" form, with, at present, no affinity 

 for chromatic stains. Only the chromatin united with the 

 plastinoid basis stains up, and the liquid spherules are to be 

 regarded as being imbedded in this matrix or ground-substance. 

 There is not the least evidence in favour of the excretory 

 nature of this vacuolar expulsion in Cystobia; in none of 

 my sections of adult trophozoites with uniformly vacuolated 

 karyosomes is there any sign of chromatoid grains or spherules, 

 either in the nucleus or in the cytoplasm. Moreover, the 

 subsequent history of the karyosome supports the view I have 

 taken here. 



(6) Commencement of Sporulation. 



(a) Bncystment. 



Encystment in Cystobia is much simpler than in most 

 Gregarines, In fact, it is often difficult to speak of any real 

 encystment at all. 



C. irregularis. — It is no unusual thing for sporulation in 

 C. irregularis to begin before the animal has evaginated 

 the wall of the blood-vessel, and while it still has the adult 

 ovoid form. The Gregariue drawn in Minchin's fig. 2 (loc. 

 cit.), which remains, unfortunately, the eai-liest stage with 

 more than two nuclei that I have seen, was still in the blood- 



' Cuenot, again, describes a sudden appearance of intensely staining 

 cliromalic grains (" clu'omosonies ") in the nucleus of Monocystis, after a 

 dissolution of some of llic karyosoiues liad taken place in the nucleoplasm. 

 Although this author does not appear to liavc seen any tiling significant therein, 

 1 should say the two facts stand in close relation to each other. 



