SEXUAL PHENOMENA IN THE PROTOZOA 



215 



short resting period the cyst breaks and an innumerable quantity of 

 fine spores pour out (F). 



Fig. 116. — Conjugation of Cercommia s. [DALLINGER and DRYSDALE.] 

 The vegetative cells increase by transverse division (A. B). When sexually mature they become 

 amcebcid, and then fuse (C, D). The result is a zygote (£), which ultimately bursts and liberates 

 masses of spores (/•). 



In Tetramitus, one of the Polymastigida, a similar period of repro- 

 duction by longitudinal division finally results in amoeboid forms 

 which conjugate, forming cysts and spores (Fig. 117). The process 



