270 II. I.YNDIIUUST DIJKK. 



these cases its vacuolated structure is very plain (fig. 7). As 

 a rule, however, the karyosome shows vei-y deeply stained in 

 the adult nucleus. Besides the nucleus there are usually to 

 be seen scattered throughout the body patches of a substance 

 which stains deeply with chromatin stains. These patches 

 have been described by Berndt (1) and others, and are espe- 

 cially numerous in the protomerite. Comes (7) has recently 

 shown that these appearances in Stenophora are probably 

 due to metabolic products, and are not nuclear. There are 

 also deeply stained granules in connection with the epirnerite 

 processes in sections stained with iron-ha3matoxylin, as 

 described by Schellack in Echinomera liispida (17). 



Cyst-Formation axd DevELorMKNT op the Spores. 



The act of association of two animals to form a cyst has 

 not been observed in the living animals. As indicated above, 

 in the sporont the epirnerite tends to become less prominent, 

 while a pad of cuticle forms anteriorly. Simultaneously with 

 this shortening of the long axis of the body the protomerite 

 increases in breadth and bulges, particularly around the 

 edges of the apical cuticular pad. From sections it would 

 seem that the two animals come together with their epi- 

 merites in contact. A ring of cuticle now arises around the 

 base of the terminal pad in one animal. Into the cup formed 

 by this ring the cuticular pad of the other gregarine is 

 inserted, while external to, and dovetailing with the ring of 

 the cup, a similar ring of cuticle arises in the second animal 

 (fig. 37). In very young cysts in which the nuclei of the 

 two animals are still unaltered the above arrangement of 

 the parts is very clear; bat as development proceeds the 

 septum of cuticle dividing the encysted sporonts becomes 

 increasingly irregular. In this region in the earlier cysts 

 there are patches of deeply stained material suggestive of 

 membrane, which are probably the remains of the cuticle of 

 the contiguous epimerites (fig. 13). 



Behaviour of the nucleus preparatory to the 



