OOSPORE-PRODUCING ALGAL FUNGI 



"3 



tissues of the host. The different kinds of nuclear fusion, which 

 accompany fertilization, have been described previously. The oospore, 

 which is formed, acts as a zoosporangium in some cases for it gives 

 rise to numerous spores; or in other cases it produces a germ tube. 

 In most of the forms, the oogonium contains a mass of protoplasm 

 known as the oosphere. This is di\asible into an outer clearer por- 





Fig. 36. — Plasmopora vUicola. A, Conidiophore with conidiospores (nearby 

 oospores) ; B. Haustoria; C, Swannspore formation. A, 950/1 ; B. C, 600/1. (After 

 MiUardet in Die natiirlichen Pflansenfamilien I. i, p. 115), 



tion, the periplasm, and a denser more granular central portion, the 

 gonoplasm. After fertilization, the oospore develops a thick wall of 

 two layers, an extine and intine, and becomes a resting spore. It 

 accumulates fatty substances, which are utilized when the spore 

 germinates in the spring after a long winter's rest. The family has 

 had many revisions and in order to simplify matters Pythium and 

 Albugo (Fig. 37), which are placed in separate families by some 



