REPRODUCTION AND THE LIFE CYCLE 



191 



epispores open either by dehiscence (Fig. 20, B, \,) or by dis.sohition at 

 certain points, and tlie 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 miclei and 

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

 Ophryocysfis mcfuiili it is nucleated, and functions as a nurse cell or 

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



Fig. 81 



Cysts and .-ixuoiliKts of (Irenarina euneata. (After Kuschakewitsch.) ^.surface view 

 of fyst with ripe spores («) issuing from sjKtroducts (e); B, section with ripening spores anil 

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

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



gregariiies the residual mass is gradually absorbed as food tluring the 

 formation of the sporozoites. 



In some cases the residual mass of protoplasm plays an important 

 part ill the dissemination of the mature sporozoites; in Grecjarlna 

 citncdld and j)n>bably in allied forms, according to the recent observa- 

 tions of Iviis(li;d\e\vitseh ('07), (he residuum takes the form of a hollow 

 brood (liaiiiber ( liriilrdiini , of Kuschakewitsch ), and its ])roto])lasm 

 retains a (iiiaiitity of the residual clintiiiatiii from which as "am|)hi- 

 ehroinidia" the gametic iiiichi had |)i'c\ ioiisix' ])(•{•]] loniiciL 'J'his 

 resi(hial " chioiiiiinal net" coH eels in rings at the |)eri|)hcr\ and around 



