FORAMINIFERA 



79 



Fig. 66. Stages in the life cycle of Polystornella. Semidiagrammatic. A, Me- 

 galospheric form, decalcified and stained. B, Shell of the same surrounded by 

 escaping gametes. C, D, Conjugation. E, Zygote. F, Microspheric form, 

 decalcified and stained. G, Shell of the same surrounded by escaping amoe- 

 bulae. H, Young megalospheric individual with three chambers, gam. 

 gametes ; i.wh. inner whorl of spiral ; o.wh. outer whorl ; nu. nucleus, ret.pr. re- 

 tral processes; i, first chamber. 



