972 AQUATIC PHYCOMYCETES 



Kobayashi and Ookubo's fungus reported from Cladophora japonica 

 bears a strong resemblance to Sirolpidium. They described spherical, 

 thick-walled resting spores in their material. 



Pontisma lagenidioides, which appears to occur most commonly in the 

 more delicate species of Ceramium, thrives best when the alga is kept 

 under unfavorable conditions or when the host plant is dead. 



LAGENIDIACEAE 



Thallus endobiotic, holocarpic, occupying one cell or sometimes 

 extending through several cells of host, uni- or multicellular, branched, 

 or unbranched, the contents usually with a lustrous matrix within which 

 are irregularly shaped refractive clods and globules, walls giving a cel- 

 lulose reaction, the cyst of the zoospore and the infection tube frequently 

 persistent, converted at maturity into reproductive organs; method of 

 zoospore formation and behavior variable; zoospores formed wholly 

 within the sporangium or partly within it and maturing at the orifice of 

 the discharge tube, where they may or may not be surrounded by a 

 temporary vesicle, or formed completely outside the sporangium in a 

 vesicle at the orifice of the discharge tube, when mature swimming away 

 (save in Myzocytium microsporum where they immediately encyst and 

 later emerge from the cysts), (always?) of the secondary laterally 

 biflagellate type, usually with a single swarm period; plants monoecious 

 or dioecious, sexual organs consisting of undifferentiated or somewhat 

 specialized vegetative cells, periplasm apparently lacking, fertilization 

 tube sometimes produced; oospore thick-walled, with a large reserve 

 globule, formed singly in the female gametangium, which it almost 

 always nearly fills; in some species one or more resting spores (apog- 

 amous?) formed in a thallus or thallus segment. 



Parasites of fresh-water algae, primarily Conjugatae, of other Phyco- 

 mycetes, liverworts, pollen, microscopic animals, crab eggs, and, in one 

 genus (Lagena), of the roots of cultivated cereals and wild grasses. 



KEY TO THE GENERA OF THE LAGENIDIACEAE 



[Thallus one-celled, attached to the inner host wall by a thick collar of 

 callus; parasitic in roots of cereals Lagena *] 



1 Not considered in this text, see Vanterpool and Ledingham, Can. J. Res. ,2: 192. 1930. 



