SAPROLEGNIALES 807 



one or more large refractive droplets posteriorly. In the behavior of the 

 zoospores the species is said by Scherffel to resemble Saprolegnia, that 

 is, the primary zoospores undergo a period of motility before encysting, 



Ectrogella monostoma Scherffel 

 Arch. Protistenk., 52: 8. pi. 1, figs. 10-19. 1925 



Sporangium long, tubular, 4-8 u. wide, with a pronounced equatorial 

 swelling, unbranched, wall extremely thin, colorless, smooth, discharge 

 tube single, short, 2-3 \x in diameter, formed on the swelling; primary 

 zoospores few, not swarming in the sporangium, without fiagella, after 

 escape encysting in a group at the orifice, cysts 6-8 \x in diameter, 

 secondary zoospores grape-seed-like, with a ventral furrow, 8 u. long, 

 with two lateral oppositely directed fiagella; resting spore not observed. 



Parasitic in Synedra ulna, Scherffel (he. cit.), Hungary; Pimmlaria 

 sp., Sparrow (1933c: 531), United States; Synedra sp., Sparrow (1936a: 

 461, fig. 4p), Great Britain. 



The valves of the host are forced apart by means of the equatorial 

 swelling, and the discharge tube protrudes free in the medium. 



Ectrogella gomphonematis Scherffel 



Arch. Protistenk., 52: 9, pi. 1, figs. 20-21. 1925 



Sporangium broadly cylindric-oblong, about 21 \i long by 6 \x wide 

 (calculated), unbranched, forcing apart the valves of the host, wall thin, 

 smooth, colorless, discharge tubes broad, short, thin-walled, lateral, 



abnormally swollen. D-F. Thraitstochytrium proliferum Sparrow on Bryopsis 

 plumosa: D, discharged primary sporangium with secondary sporangium 

 beginning to enlarge within it; E, mature primary sporangium showing basal 

 body which will become rudiment of secondary sporangium; E, liberation of 

 spores after deliquescence of upper part of wall of primary sporangium; each 

 of the spores later becomes biflagellate. G-J. Ectrogella perforans H. E. Peter- 

 sen in Licmophora: G, abnormally swollen diatom with zoospores of fungus 

 escaping through one of the two visible discharge tubes; H, empty sporangium 

 with four visible discharge tubes; /, hypertrophied diatom with unopened 

 sporangium within which is peripheral layer of quiescent zoospores; J, resting 

 spore. 



(A-C, Scherffel, 1925a; D-F, Sparrow, 1936b; G-J, Sparrow, 1934c) 



