REPRODUCTION AND THE LIFE CYCLE 



191 



epispores open either by dehiscence (Fig. 20, B, N,) or by dissolution at 

 certain points, and the sporozoites emerge by typical contractile move- 

 ments. In the majority of cases there is a residual mass of sporoplasm, 

 which has received various names (reliquat sporal, sporenrest, sporal 

 residuum, etc.), and about which the sporozoites may be grouped in 

 characteristic manner. In some cases this residual protoplasm is more 

 than a mere degenerating mass, but is provided with special nuclei and 

 plays a definite purpose in the reproductive process. Thus, in 

 Ophryocystis mesnili it is nucleated, and functions as a nurse cell or 

 cells for the developing sporoblast (Fig. 80). In Monocystis and other 



Fig. si 











-^ 



Cysts and sporoducts of Gregarina cuneata. {After Kuschakewitsch.) A, surface view 

 of cyst with ripe spores is) issuing from sporoducts (e) ; B, section witli ripening spores and 

 points on wall where sporoducts will form; C, section showing ingrowth of finger-like sporo- 

 duct (0, which finally evaginates to form the emission ducts (e). 



gregarines the residual mass is gradually absorbed as food during the 

 formation of the sporozoites. 



In some cases the residual mass of protoplasm plays an important 

 part in the dissemination of the mature sporozoites; in Gregaritia 

 cuneata and probably in allied forms, according to the recent observa- 

 tions of Kuschakewitsch ('07), the residuum takes the form of a hollow 

 brood chamber (Bndraum, of Kuschakewitsch), and its protoplasm 

 retains a quantity of the residual chromatin from which as "amphi- 

 chromidia" the gametic nuclei had previously been formed. This 

 residual "chromidial net" collects in rings at the periphery and around 



