226 A TEXTBOOK OF THEORETICAL BOTANY 



immediately fuses with the female nucleus. The fertilized oogonium secretes 

 a thick wall round itself, and thus becomes an oospore (Fig. 217). In the 



Oogonium 



Oospore 



Oosphere 



iW 



\'^-g 



L.Antheridium 



Fig. 217. — Pythium proliferum. Spiny oogonia with 

 oosphere, left, and oospore, on right. 



oospore are a large number of oil globules which constitute the food reserve 

 of the zygote. The oospore is a drought-resisting structure, associated with 



Fig. 218. — I'vl/utuN inatnilliitutn. Spiii\ oogonia ^Mth 

 androgynous production of antheridia. 



the dessication which the Fungus may experience. The germination of the 

 oospore only takes place in the presence of moisture and may be delayed 



