HYPHOCHYTRIALES 765 



enlarged, and became a sporangium. After discharge from such spo- 

 rangia, the anteriorly uniflagellate zoospores often conjugated in pairs 

 to form a zygote, the unfused ones developing into new sporangia. The 

 zygote eventually entered a Lemna cell and became transformed into a 

 brownish, thick-walled resting spore, with from one to three or more 

 large globules. This spore upon germination gave rise to zoospores 

 which were surrounded by an evanescent vesicle. Fischer (1892:28) 

 considered R. amoeboides synonymous with R. lemnae. 



All these observations need confirmation, particularly those refer- 

 ring to zoospore flagellation. 



? Reessia amoeboides Fisch 

 Sitzungsber. Phys.-Med. Soc. Erlangen, 16: 32, pi. 1, figs. 1-6. 1884 



"Thallus amoeboid with several pseudopods during the vegetative 

 developmental stages. Zoosporangia solitary, hyaline, smooth with an 

 elongate straight or curved cylindrical exit tube which may often pen- 

 etrate several host cells. Zoospores large, hyaline, spherical or oval 

 with a conspicuous refractive globule; frequently fusing in pairs and 

 forming biflagellate motile zygotes which infect the host cell and 

 develop into dormant spores. Resting spores oval or spherical with a 

 smooth light brown exospore and a hyaline endospore; containing one 

 to several large refractive globules; endospore expanding out of the 

 ruptured exospore during germination and forming a vesicle in which 

 zoospores are eventually developed ,, (Karling, 1943: 642). 



Parasitic in the epidermal cells of Lemna minor and L. polyrhiza, 

 Germany. 



? Reessia lemnae (Fisch) Karling 



Amer. J. Bot., 30:642. 1943 



Chytridium lemnae Fisch, Sitzungsber. Phys.-Med. Soc. Erlangen, 16:43, 



pi. 1, figs. 7-9. 1884. 

 Olpidium lemnae (Fisch) Schroeter, Kryptogamenfl. Schlesien, 3(1): 181. 



1885. 



Sporangium spherical, thin-walled, with a thin smooth colorless wall 

 and a long narrow slightly irregular discharge tube; zoospores spherical, 

 with a small colorless globule and an anterior flagellum from two to 



