LIFE-CYOLK OF " OYSTOEIA " IRREGULARIS (mINCH.). 5 



two Gregarines have become interlobed in a complicated 

 manner, though each still remains quite distinct from, and 

 not in any way united with, the other. Little uninuclear 

 protuberances appear on the surface of both, and these are 

 finally cut off as primary sporoblasts or gametes. According 

 to Siedlecki, the gametes formed from one associate or 

 parent-individual are perfectly similar to those formed from 

 the other, and therefore isogamous. Soon after liberation 

 the gametes throughout the whole of the cyst are seen to be 

 in a state of rapid motion, the resnlt of which is to get them 

 all thoroughly mixed. They next conjugate in pairs, each 

 member of a pair coming, in all probability, from a diffei'ent 

 half of the cyst. The definitive sporoblast becomes a spore, 

 containing eight sporozoites, in the usual manner.^ 



On the other hand, in Stylor hy nchus and Ptero- 

 cephalus, two members of the sub-order Septata, Leger 

 (22) and Leger and Duboscq (23) find a differentiation of the 

 gametes into male and female, with, consequently, anisoga- 

 mous conjugation." All the elements arising from the same 

 chamber of the syzygy are of the same sex, so that we may 

 consider the two sporonts or associates themselves as respect- 

 tively male and female. The male gametes are motile, elon- 

 gated or fusiform in shape, Avith a minute rostrum anteriorly 

 and a long flagellum posteriorly. Those of Pterocephalus 

 are much smaller than the massive female elements of that 

 parasite; while in Stylorhynchus both kinds are about 



' Cueiiot (10), soon after, described very similar facts for different species 

 of Mouocystis in the earthworm, aud also for Diplocystis spp., coelomic 

 parasites of the cricket (Gryllus). As regards the latter parasites, there is 

 no reason to doubt that conjugation is completely isogamous, as in L an k es- 

 ter ia. While, however, both Cecconi (8) aud Prowazek (31) have confirmed, 

 in the main, Cueuot's version of the process in Monocystis, Brasil, in a 

 recent note (4) states that conjugation in this form is not completely isogamous, 

 distinct, though slight, differences between the gametes being observable (see 

 below, pp. 51 and 70.) 



' It is important to notice that anisogamous conjugation is not universal in 

 the Septata, both Berndt (1) and Paehlcr (29) having described isogamy in 

 various species of Gregariua. 



