712 



AQUATIC PHYCOMYCETES 



fully mature oospores, however, only a single, presumably fusion nu- 

 cleus, can be observed (Sparrow, 1 953b). How long the encysted oospores 

 remain viable is not known. Fully mature spores dried for three months 

 on cover slips have germinated when placed in water, and soil samples 

 baited four years after collection have yielded the fungus (Springer, 

 1945b). It is probable, therefore, that the oospore can remain alive in 

 the soil during ordinary periods of tropical drought. Upon germination 



D \ 



Fig. 52. Sexuality in Gonapodya polymorpha 



A. Large internally proliferated female gametangium with nonflagellated 

 gametes and smaller proliferated male gametangium from which gametes 

 are emerging. B. Tip of plant showing a discharging female gametangium with 

 male gamete adherent, a discharging male gametangium and an empty 

 proliferated male gametangium. C. Amoeboid female gamete free in water. 

 D. Nearly complete fusion of a male and a female gamete. E. Same; flagellum 

 of male gamete active. F. Encysted zygote free in water. 



(Contributed by Robert M. Johns) 



a single small pore is formed in the oospore wall, through which a 

 hypha emerges. The hypha elongates indefinitely, branches, makes 

 contact with bits of organic material, and reestablishes the fungus. 

 Reproductive organs of either type develop, or the mycelium may con- 

 tinue its vegetative growth. 



In Gonopoclya, sexual reproduction, according to Johns and Benjamin 

 (1954), is effected by posteriorly uniflagellate male and nonflagcllatc 



