SEXUAL PHENOMENA IN THE PROTOZOA 



215 



short resting period the cyst breaks and an innumerable quantity of 

 fine spores pour out (F). 



D 



Fig. 116. Conjugation of Cercomonas. [DALLINGER and DRYSDALE.] 

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

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

 masses of spores (F). 



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 



