Reproduction and Life-Cycles 59 







yry:^^% 











Fig. 2. 3. A-C. Surface changes during fission in Amoeba protcus; earlv 

 division (A); stage with nucleus in anaphase (B); shortly before constriction 

 of the body (C): diagrammatic fafter Chalkley and Daniel). D. Reserve shell- 

 plates stored in Euglypha; x8I0 (after Hall and Loefer). Key: /, ingested 

 food; 71, nucleus; s, reserve shell-plates. 



certain species, there seems to be a definite division-plane which is not 

 displaced by amputations just before fission (256). However, the plane 

 of fission in Peritrichida passes from the oral to the aboral end and is 

 morphologically longitudinal (Fig. 2. 4, A-C). The plane of fission in 

 Opalinidae also is oblique or almost longitudinal. CyatJwdiniian piri- 

 jorme (Fig. 2. 4, D-F) is unusual, in that the plane of fission passes 

 through the originally longitudinal axis of the body but separates the 

 posterior ends of the daughter ciliates in late fission (164). 



Reorganization in ciliates is often striking, and may involve macronu- 

 clei as well as cytoplasmic structures. The old cirri are resorbed in Urojiy- 

 chia (229), dedifferentiation of the peristomial area occurs in Bursaria 

 (212), and resorption of the peristomial membranelles in Fabrea (79). 

 In Chilodonella imcinatus (165), the old pharyngeal basket, cytostome, 

 and many body cilia are resorbed. On the other hand, Euplotes (107), 



