20 



Maurice Crowther Hall 



which stain pink with Heidenhain's haeinotoxyHn, are in two or 

 three local areas and in the granular area or its border. There is 

 a suggestion of individual gregarine encystment here, the clear 

 area being perhaps the protomerite and the partition the septum. 

 The third section shows the cyst content to be vacuolated, the 

 nuclei occurring in local peripheral areas and along the region of 

 the degenerating partition. 



Vacuolization of the cyst content occurs in 13 per cent of -the 

 cysts. Besides these 19 per cent show the spores or chromatin 

 arranged in a crescentic outline, the tips of the crescent enclosing 

 a space that may be empty or have a slight, apparently degenerate 

 content. This may be a modification of the vacuolization, and as 

 it .occurs in yellow as well as white cysts, of which I find a few, it 

 seems to be a mere incidental feature of the cyst ripening of 

 Hirmocystis rigida. 



An interesting case is that of a cyst which was ripened for 141 

 days and on sectioning showed two gregarines intact with the 

 septa of both individuals complete. No nucleus was present in 

 either, and the body content of both stained evenly. 



The spores are oval, about 5 fx long and 2.5 jx in diameter. The 

 chromatin first shows as a thick central cylinder, later aggregated 

 as two dense spheres at the poles and then as four short parallel 

 rods at each end of the sporocyst, the long axis of the rods par- 

 allel to the long axis of the spore. Six cysts ripened up to a pe- 

 riod of 153 days show the spores to be fairly uniform as regards 

 chromatin and development. Four out of five cysts ripened over 

 this time show a few sporocysts with a dense chromatin content 

 and many that appear to have no chromatin. This may indicate 

 sporocyst degeneration. My failure to get the cysts to dehisce 

 has prevented any observations on the sporozoites. 



The cyst structure with its relatively thin walls enclosing a solid 

 mass of spores shows that no sporoducts are present and that 

 dehiscence is by simple rupture. 



The characters of the gregarine may be briefly stated as fol- 

 lows : epimerite, — verv small, regular and simple, is reduced to 

 level of protomerite in early growth ; gregarines commonly in 

 association and with septum in primite and satellite ; cysts, — de- 



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