SAPROLEGNIALES 805 



ECTROGELLA BACILLARIACEARUM Zopf 



Nova Acta Acad. Leop. -Carol., 47: 175, pi. 16, figs. 1-24. 1884. Emend. 

 Scherffel, Arch. Protistenk., 52: 5, pi. 1, figs. 1-9. 1925 



(Fig. 60 A, p. 806) 



Sporangium tubular, fusiform, ellipsoidal or occasionally spherical, 

 variable in size, up to 200 [x or more in length, unbranched, generally 

 forcing apart the valves of the host, wall thin, smooth, colorless, 

 discharge tubes short, thick-walled, from one to ten, arranged in one 

 or two files corresponding in position to the girdle bands of the host 

 cell; primary zoospores moving within the sporangium, pyriform, 4 \l 

 long by 2 [i wide, with two equal, laterally inserted flagella 4 ;jl long, 

 cysts spherical, not grouped compactly at the orifice, secondary zoo- 

 spores ovoid, with an anterior broad oblique cleft, flagella unequal, 

 movement darting, with pauses and frequent changes of direction; 

 resting spore not observed. 



Parasitic in Synedra sp., S. lunularis, Gomphonema sp., Pinnularia sp., 

 Zopf {he. cit.), Germany ; Synedra ulna, Meridion eirculare, Scherffel 

 (he. cit.; 1902b), Domjan (1936: 52, pi. 1, fig. 167), Hungary; Synedra 

 sp., Gomphonema sp. (coll. de Wildeman, Marchal), de Wildeman 

 (1890:26), Belgium; diatoms, de Wildeman (1894:155), France; 

 diatoms, de Wildeman (1895a: 65), Switzerland; diatoms, Atkinson 

 (1909a: 338), Pinnularia sp., Sparrow (1933c: 531), Nitzschia sigmoidea, 

 Karling (1942e: 20), Pinnularia sp., coll. Bartsch, Wolf (1944:43), 

 United States; Synedra capitata, Friedmann (1952: 200), Austria. 



The species has generally been found in the early spring. Zopf 

 observed that in nature about 75 per cent of the diatoms were infected, 

 and under laboratory conditions nearly 100 per cent. He concluded 

 that this was due to the enormous numbers of zoospores produced. 



When more than one thallus is formed in the host cell (occasionally 

 as many as thirty appear there), its tubular shape is lost and it tends to 

 become more ellipsoidal or spherical. Aside from differences already 

 noted in the zoospore, Scherffel observed that the primary swarmer 

 does not contain the solitary globule characteristic of the chytrid spore, 

 but, rather, bears posteriorly several refractive granules. The secondary 

 spore, on the other hand, contains dense hyaline plasma anteriorly and 



