BCTROQKLLACEAE 



21 



viously of a different nature than starch grains. The 

 structures described for Focke as spores of diatoms, 

 which Pfitzcr interpreted as a part of Ci/mbanche 

 fockei. relate to a species of the Mwo/.ooidia. (ii/m- 



noccoccu* fockei, according to Zopf ('8 1-1). pp. 120. 

 126 | and Fischer. 



E. PERFORANS Petersen. 1905. Over. K'gl Dansk. 

 Videos. Selsk. For. (">); Miii, ftg. VII, 1-H. 



Zoosporangia solitary or up to ."> ill a cell, smooth 



hyaline; wall staining light violet with chloro-iodide 

 of sine; spherical 20-85/*, oval, elongate, 22 23// 

 26 10,.. sometimes slightly irregular, and be- 

 coming partially extramatrical at maturity with 1 to 

 S short, very broad, !>-12 /i X 8-10 /i. exit tubes. 

 Zoospores hyaline with a refractive globule at the 

 anterior end. emerging fully formed and swimming 

 directly away, pyriform and somewhat curved with 

 the two rlagella attached anteriorly (?) and op- 

 positely directed in swimming, relative lengths of 

 flagella unknown; motion during swimming uneven 

 and twisting. Rest spores spherical, 14-19 /t, hya- 

 line, smooth, thick-walled with one large or several 

 smaller refractive globules; germination unknown. 

 Parasitic in Licmophora Lyngbyei, Licmophora 

 sp.. and Synedra ulna in Denmark (Petersen, I.e.; 

 Sparrow. '.'iM; Licmophora abbreviate!, Striatella 

 unipunctata and Verticella sp., in Mass., U. S. A. 

 Sparrow. '3<>b). causing distortion of host cell and 

 complete destruction of the host protoplasm. The 

 author has recently ('42) observed this species in 

 great abundance in /.. abbreviata and L. fiaf/etlata at 

 Beaufort, North Carolina. 



This species appears to be a virulent parasite and 

 may attain epidemic proportions in Licmophora, ac- 

 cording to Sparrow ( '36b). In the shape of its spo- 

 rangia with numerous broad exit tubes this species 

 is strikingly similar to K. I.icmophorae, and Scher- 

 ffel was accordingly of the opinion that the two spe- 

 cies may prove to be identical. It is to be noted, how- 

 ever, that the has,- of the exit tubes of E. perforans 

 is not thickened and does not form a spreading ap- 

 paratus as in K. I.icmophorae, nor do its zoospores 

 encyst in a group at the mouth of the exit canals as 

 far as is now known. It is primarily for these rea- 

 sons that Sparrow ('84) regarded K. perforans as a 



distinct species. It is not improbable, however, that 

 when intensive comparative studies have been made 

 of both species and their range of variation worked 

 out. they may prove to lie identical. 



Sparrow I '36 ) described the zoospores as possi- 

 bly anteriorly birlagellate with both flagella op- 

 positely directed in swimming. He was unable to de- 

 termine the relative lengths of the rlagella. and it is 

 not known whether the zoospores are iso- or hetero- 

 cont. Sparrow found that as much as eighty-eight 

 per cent of the Licmophora cells in a single mount 

 may be parasitized by this species. The zoospores 



are callable of attacking other hosts as well, since 

 species of I'orticella which ingest free swimming 

 zoospores may in turn be attacked by the swallowed 

 parasites and completely destroyed. 



No conclusive evidence of sexuality has been 



found in this speeies. Petersen found isolated thick- 

 walled resting spores (fig. 85) in several instances. 



but these were not accompanied by empty antheridia 



or companion cells. Sparrow ('84), on the other 

 hand, believed that the spores are surrounded by a 

 thin envelope. In one instance he found an empty 

 hemispherical cyst. :( /i in diameter, attached to a 

 fully mature spore. However, no stages of fusion 



were observed. 



E. MONOSTOMA Scherffel, I.e.. p. 8, pi. 1. lifrs. 10-19. 



Zoosporangia solitary, elongate, tubular, some- 

 what spindle-shaped, i-8 fi. in diameter, slightly 

 swollen in the median region from which a single, 

 short, 2-3 /x thick, cylindrical exit tube or papilla 

 arises; exit tube and part of the sporangium wall 

 staining intensively violet with chloro-iodide of 

 zinc. Primary zoospores aflagellate, gliding out of 

 the sporangium and encysting in a group at the 

 mouth of the exit tube; individual cystospores 

 spherical, 6-8 ix in diameter, wall showing a marked 

 cellulose reaction; secondary swarmers, lemon- 

 shaped, 8 it. long, with a ventral furrow, heterocont 

 (?), shorter fiagellum directed forward and the 

 longer one dragged along behind while in motion. 

 Resting spores unknown. 



Parasitic in Sunedra ulna in Hungary; Pinnii- 

 laria sp. in New York, U. S. A. (Sparrow, '33) and 

 Sunedra sp. in England (Sparrow, '36a). 



According to Scherffel and Sparrow, this species 

 differs from the other members of Ectrogella only 

 by the presence of one short exit tube. Except for 

 this character and the median bulge (fig. 19) its 

 thallus and zoosporangia are identical to those of E. 

 bacillariacearum which parasitize the same host. 

 Obviously the presence of one or more exit tubes is 

 not always a distinctive specific character. However, 

 the secondary zoospores of E. monostoma appear to 

 be considerably larger (8 /*. long) than those of E. 

 bacillariacearum which Zopf reported to be only 

 2 to 3 fi. in diameter. Zoospore size is a more constant 

 specific cell character, and if further observations 

 confirm this difference the validity of E. monostoma 

 will be established. 



E. GOMPHONEMATIS Scherffel, I.e.. p. !», pi. 1. Bgs. 

 20, 21. 



Zoosporangia solitary, oval, oblong, egg-shaped 

 with 1 or usually 2 short exit tubes located at the 

 ends. Zoospores diplanetic. primary zoospores egg- 

 shaped and somewhat elongate. 3 /x long, with a lew 

 highly refractive granules and the two equal flagella, 

 slightly longer than the spore body, inserted almost 

 at the apical end: swarming within the sporangia, 

 later emerging singly and swimming away (?) or 

 encysting in a group at the mouth of the exit tubes; 

 granules fusing during encystment to form a large 

 refractive globule as in some rhizidiaceous chytrids; 

 germination of cysts, and structure of secondary 

 zoospores unknown. Resting spores unknown. 



