LIFE-CYCLE OF " CYSTOBIA " IRREGULAKIS (mINCH.). '7 



and iudependeub development of the sporoblasts, co-existent 

 (e.g. Ophryocystis^ Leger [20]). Again, in Ceratospora 

 mirabilis from tlie body-cavity of Glycera, Leger (19) de- 

 scribes and figures the formation of (many) sporoblasts and 

 spores separately in the two associates, the septum appa- 

 rently remaining unabsorbed and preventing copulation. If 

 this can be relied upon as being a normal mode of spore- 

 formation, it would seem that we have here, also, the 

 beginning of this independent development of the sporo- 

 blasts.^ 



We have next to consider the case of two or three forms 

 which are said to be capable of encysting and successfully 

 sporulatiug alone, in addition to following the customary 

 course. The evidence brought forward so far is, however, 

 by no means conclusive. Leger has described (loc. cit.) 

 solitary encystment and sporulation in Gonospora varia,^ 

 as well as the permanent encystment of a couple. Brasil, 

 however, in his paper on the same species (3) says nothing 

 about the independent (complete) sporulation of each member 

 of a couple. ~ 



On the other hand, Brasil draws attention to the work 

 of Caullery and Mesnil on Clonospora longissima and 

 Selenidium, spp. Unfortunately, the observations of these 

 authors are too scanty to help much in deciding this question. 

 Concerning the former parasite they remark (7) that the cysts 

 seem formed either of one or two individuals, but nowhere do 

 they definitely state that the cases of solitary encystment 

 were successful. In addition the occurrence, now and again, 



' It. must be confessed that this observation (and also that of Gonospora 

 below) stands f,'veatly in need of corroboration. Leger's early work was all 

 done, it must be remembered, before true conjugation was known. Probably 

 sometimes, at any rate, the dividing septum breaks down, allowing conjugation 

 to take place, for in some cysts of Ceratospora active movement of the 

 gametes (Schneider's "danse des sporoblasts") was observed. 



- Brasil notes an instance of a cyst of Urospora in whicii one individual 

 liad died off and was degenerating, while the other, to judge from its healthy 

 appearance, seemed to be pursuing its normal course, with what ultimate 

 success, however, we arc not informed. 



