THE FUNGI : ARCHIMYCETES AND PHYCOMYCETES 219 



movement, each swims away. Zoospores may frequently fail to gain 

 the outside of the zoosporangium, but even under such conditions they 



Zoosporangium 



Fig. 209. — Moiioblepharis sphaerica. Zoosporangium. 



germinate, producing a single hypha from which a fresh mycelium is 

 formed eventually. 



Sexual Reproduction 



Sexual reproduction is favoured either by warm conditions or by freezing. 

 The process differs somewhat in the species, firstly in the relative positions 

 of the antheridia and oogonia, and secondly in the position where the oospore 

 matures. 



In some species, e.g., Monoblepharis polymorpha, M. insignis, M . fasciculata 

 and M. sp. nov.,^ the antheridium appears to be inserted on the oogonium, but 

 a study of their development shows that in reality the oogonium is formed 

 beneath a terminal antheridium, although as the oogonium matures the 

 antheridium becomes pushed to one side. In others, e.g., Monoblepharis 

 sphaerica and M. hypogyna, the antheridium may develop below the oogonium. 



The Antheridium 



The antheridium is an oval structure cut off by a septum and is from 

 the first multinucleate. The cytoplasm is homogeneous and when mature 

 is divided transversely into from four to eight uninucleate antherozoids. 

 A small opening appears in the apex of the antheridium, and towards this the 

 antherozoids crawl by amoeboid motion, each trailing its single long flagellum 

 * This species, not yet described, is illustrated in F"ig. 211. 



