FISHERIES, GAME AND FORESTS. 



185 



however, they rapidly grow in size until they attain their largest dimensions (twenty- 

 five microns). While the amoeboid forms assume any characteristic shape in the 

 lymph, they have only one general form in the muscle cells. Here, constrained 

 apparently by the tightly pressed muscle fibres, they are always elongate, sometimes 

 fusiform, sometimes club-shaped (Figure 6). They can always be distinguished from 

 the nuclei of the muscle cells by their characteristic shape and by their densely 

 granular plasm. 



Here, as in the spores and sporozoites, a nucleus could not be distinguished. But 

 the deeply staining granules appeared like chromatin and in the older individuals they 



BCD E 



Figure 7.— Spore formation. A, Young- sporozoite at the beginning of the amoeboid stage. B and D, large amoeboid 

 forms prior to spore formation. In D the deeply staining granules have begun to collect in groups. C and £, 

 spore-forming cysts. The protoplasm is again reticulate and the spores are completely formed. Camera draw- 

 ing, x 2000 diameters. 



were grouped together in small aggregates which formed the beginning of the spores 

 (Figure 7, D). 



Spore formation is always preceded by encystment of the animal within a delicate 

 membrane. The cell leaves the muscle tissue, and in the lymph of the body cavity 

 it rounds out into a sphere. The amoeboid individuals, when ready to form spores, 

 are comparatively large, and the cysts are of variable size, in some cases measuring- 

 twenty microns or more in diameter. The spores are formed by aggregation of the 

 deeply staining granules (chromatin ?) instead of by nuclear division as in other 

 Sporozoa (Figure 7, B, D). This leaves the protoplasm with a clearly marked 

 reticular structure as in the early stages (Figure 7, C, E). A variable number of 

 spores is the rule. In some cysts only twelve were seen, in others sixteen or even 

 more. In some cases the cysts appear to be differentiated into a more hyaline 



