LTFE-CYOLE OF " CYSTOBIA " IRREGULAETS (mINCH.). 53 



conjnganfc, a very sliglit movement or mutual attraction will 

 briug two such, when set free, into contact. 



There are, besides, very good reasons for the absence of 

 this peculiar and characteristic phenomenon. In the first 

 place, since practically all the cytoplasm is brought into use, 

 there are neither lobes nor processes (as in Stylorhynchus 

 and Lankesteria), nor a large central residuum formed 

 by the two gregarinoid somata (as in Diplocystis and 

 Gregarina cuneata) to be, as it were, circumnavigated, 

 either actively or passively, before selective fusion can result. 

 On the other hand, again, there is no apparatus for pro- 

 ducing the movement.^ Hence, considering all things, I 

 no longer wonder, since examining my fixed and stained 

 material, that I could not see any movement when observing 

 cysts at this stage alive, and I do not believe that any such 

 occurs. 



The actual union. — In sections through a cyst in which 

 conjugation is actually taking place, various stages are to be 

 met with indiscriminately throughout the cyst — here the two 

 cytoplasms commencing to fuse, there a single definitive 

 sporoblast with the two nuclei still separate, and, lastly, a 

 fully-formed zygote. Hence there is a slight variation in 

 time of the process to be noticed, probably due to the primary 

 sporoblasts not all being cut out at the same moment. The 

 actual conjugation processes are, however, better seen in cj'sts 

 which have been fixed and stained whole and then crushed 

 on a slide. If this is done carefully, the exact stage reached 

 in each case can be readily observed. All degrees in the 

 union are seen in fig. 57, drawn from such a crushed prepara- 

 tion ; d-h show successive stages in the fusion, and at y we 

 have the definitive spoi-oblast, copula, or zygote formed. The 



^ Leger, in his interesting paper (22), shows that tiie chief function of the 

 fusiform motile gametes (sterile male elements) in Stylorhynchus is to bring 

 about, by their vigorous movements, the " melee sexuelle." Again, Berndt 

 (loc. cit.) finds that, in the mealworm Gregarines, the unused cystal "reli- 

 quats" become amoeboid and send out processes of various lengths, which 

 .serve to drive the peripherally situated gametes round in the cyst aud mix 

 them thoroughly together. 



