^3^ A TEXTBOOK OF THEORETICAL BOTANY 



There is some doubt as to precisely where the reduction division occurs. 

 Some authorities claim that it takes place during the multiplication of nuclei 

 in the formation of the oogonium and antheridium, while according to others 

 it occurs in the first division of the germinated oospore, and on the whole this 



Fig. 224. — Peronospora sp. Mature oospore with rugose 

 exospore in tissue cell. 



latter view seems the more likely, on account of what is known of the nuclear 

 behaviour in allied genera of Fungi. 



The life-cycle of Peronospora may therefore be represented by the 

 following diagram (Fig. 225) : — 



Ooipore 



Fertilization 

 Tube 



"eronospora 

 Plant 



Fig. 225. — Life-cycle oi Peronospora. 



