502 AQUATIC PHYCOMYCETES 



Parasitic on motile Cymatopleura solea, Scherffel (he. cit.), Melosira 

 varians, Domjan (1936: pi. 1, fig. 1 10), Hungary; Navicula sp., Sparrow 

 (1933a: 63, fig. 1 a-c, m), United States; Synedra sp. (?), Tabellaria 

 sp., Sparrow (1936a: 437, fig. 3 g,t; fig. 4a), Nitzschia sigmoidea, Canter 

 (1947b: 101, figs. 6-7; pi. 10, figs.7-8), Fragilaria crotonensis, Tabellaria 

 flocculosa var. asterionelloides, Canter (1950c: 273, figs, a-f), Great 

 Britain; Melosira ambigua, Melosira sp., Rohde and Skuja (in Skuja, 

 1948: 381, pi. 39, figs. 14-21), Sweden. 



A curious adaptation of this fungus to its mode of life on moving 

 diatoms has been pointed out by Scherffel (see under "Structure of the 

 Thallus," p. 53). He also noted that the method of development of the 

 sporangium in this species is similar to that in Podochytrium. The body 

 of the original zoospore persists, unexpanded, as the knoblike base, 

 while the remainder of the sporangium is formed by elongation and 

 expansion of the apical part. In contrast to most species of Podochytrium, 

 however, the base remains continuous with the rest of the sporangium. 

 In the Hungarian material no rhizoids were found within the host and 

 this, together with the fact that several fungi were present in various 

 stages of development on the moving diatoms, suggested to Scherffel 

 that the adherent organism might be only a saprophyte on the gelatinous 

 coating. Later observations (Sparrow, 1933a) disclosed that a true 

 endobiotic system was developed and that the fungus might ultimately 

 destroy its host. 



Canter's (1947b: 102) variety acaulis is placed in synonymy. She 

 erected it for a stalkless form on Nitzschia sigmoidea, but later (1953: 

 293) suggested its suppression, stating that the presence or absence of 

 a stalk was evidently related to whether or not mucilage surrounded 

 the diatom wall. 



Chytridium lagemda Braun, sensu recent. Scherffel, appears to differ 

 from C. versatile only in its host, in its smaller size, and in the somewhat 

 broader base of the sporangium. 



? Chytridium versatile var. podochytrioides Friedmann 

 Osterrisch. Bot. Zeitschr., 99: 186, figs. 2 a-h. 1952. 

 Sporangium clavate or obpyriform, tapering proximally to a knob- 

 like sterile base, 1 .7-2. 1 jj. broad by 2. 1-3. 1 u high, which is generally cut 



