240 



A TEXTBOOK OF THEORETICAL BOTANY 



Inside the oospore the zygote nucleus begins to divide, resuhing in the 

 formation of about thirty nuclei, after which activity temporarily ceases, and 

 the oospore may remain for a long time in this condition. Later when 

 germination occurs the wall splits and about a hundred zoospores are liber- 







Antheridium 

 Fertilization tube 



Oospore 

 Periplasm 



^ 



$' 



Fig. 231. — Cystopus cmididus. Mature oospore in 

 host tissue. 



i 



ated. It is obvious, therefore, that prior to germination further nuclear 

 divisions must take place, and though it has never been conclusively demon- 

 strated, it appears likely that each of the thirty nuclei found in the oospore 

 after fusion undergoes two divisions, which involve a meiosis, so that the 

 nuclei of the zoospores are monoploid. 



The life-history of Cystopus caudidiis may be represented by the following 

 diagram (Fig. 232) : — 



Zoospore 



Oospore 



Fertilization 

 Tube. 



Conidiospores 



Antheridium 



Cystopus Mycelium 

 Fig. 232. — Life-cycle of Cystopus candidus. 



