I w,i NIDIACEAE 



89 



short flagellum directed forward and the long one 

 backward; delimited in an oxtramatric.il vesicle ( ?) 

 or formed within the sporangium and escaping 

 singly in succession; germination in situ fairly coin 

 moii. forming a yeast-like bud in germination. Game- 

 tangia occurring among the zoosporangia ; oogonia 

 oval, egg-shaped and ellipsoidal; antheridia elon- 

 gate, cylindrical and slightly spindle-shaped. 

 Oospores spherical and ellipsoidal with a thin endo- 



Spore and a stellate or polygonally-sculptured e\o- 



spore; germinating by becoming transformed di- 

 rectly into a aoosporangium with an exit tube. 



Parasitic in nematodes in Germany (Zopf, I.e.). 

 Russia (Sorokin, I.e.). France (Dangeard, '06), 

 and Bulgaria (Valkanow/31). 



According to Dangeard, this species is very 

 abundant in France as a parasite of nematodes, oc- 

 curs frequently in association with Protascus subuli- 

 formt, and may easily he mistaken tor the latter 

 species when the thalli are young and reduced in 

 size. So tar as the author is aware there are no meas- 

 urements of the thallus, oogonia, antheridia and 

 zoospores of this species to be found in the litera- 

 ture. Zopf listed M. vermicolum as a variety of M. 

 proliferum, but Fischer raised the former to specific 

 rank on the grounds that it parasitizes an entirely 

 different group of organisms. No cross inoculations. 

 however, have been made to determine whether or 

 not M. vermicolum will parasitize algae. 



Zopf reported that the zoospores are delimited in 

 an extramatric.il vesicle at the tip of the exit tube, 

 while Dangeard described them as being fully 

 formed within the sporangium. According to the lat- 

 ter worker a few of the swarmspores emerge in a 

 small vesicle (fig. 28) which soon bursts and sets 

 them free, while the remaining ones emerge singly 

 and in succession. It is to be noted here that zoospore 

 emission in Mysocytium sp., described by Thomp- 

 son ('84) in Spirogyra sp., is very similar to that re- 

 ported by Dangeard. with the exception that no 

 small vesicle occurs around the initial emerging 

 spores, further study is accordingly necessary to 

 determine which or if both of the reported methods 

 of zoospore formation and emission occur. It is par- 

 ticularly noteworthy that Dangeard figured the zoo- 

 spores as heterocont with the short cilium directed 

 forward and the longer one backward (fig. 20), as 

 in the case of secondary swarmers of Lagenidium 

 species; whereas in other species of Mysocytium 

 they are figured as isoeont. In this respect also fur- 

 ther study of this species is very essential. 



Maupas' ('15) M. polymorphum, the thallus of 

 which breaks up into free and independent spo- 

 rangia at maturity, probably relates to this species. 

 He merely mentioned it in relation to Protascus and 

 apparently lias never figured or described it further. 



M. MEGASTOMUM Wildcman, 1893. Ami. Soc. Beige 

 Mien.. 17: S3. PL li. figs. 6-10; pi. 7. figs. 19-80. 

 Ancyliste* mmrU Skvortzow, 1925. Arch. Protistk. 51: 

 133. figs. 7-10. 



Thallus at first cylindrical. 7.4-12/1 thick, un- 



branched; later becoming constricted and septate, 



consisting of 5 IS moid, ellipsoid, elongate and 

 somewhat cylindrical. 9-26 ft X 12 ■">(>/'. segments 

 with a single exit tube which is inflated, globular 

 3.7— 1.2 fi. in diameter, irregularly lageiiil'orin and 

 appressorial-like inside of host wall, and may e\ 

 tend to a distance of 150/1 on the outside of host. 

 Size, structure .and behavior of zoospores unknown. 

 Antheridia oval and spindle-shaped; oogonia oval, 

 barrel-shaped. 12-19.5 p X 7.4-12 p ; oospores 

 Spherical, 7.4—13/*, with a thick, hyaline, smooth 

 wall and several refractive globules; germination 

 unknown. 



Parasitic in Closterium attenuatum and Spiro- 

 taenia sp. in Belgium (de Wildcman, '93, '95, '96) ; 

 Closterium sp. in Manchuria (Skvortzow, I.e.); 

 Closterium sp. and Pleurotaneum trabecula in Bo- 

 hemia (Cejp, '.'55); <". striolatum and C. areolatum 

 in North Carolina. U. S. A. (Berdan, '38). 



Whether or not .1/. megastomum (de Wildcman) 

 forma Skvortzow (I.e.. p. 431), which occurs in 

 Closterium sp. is a variety or form of de Wildeman's 

 species is uncertain, but the writer is at present of 

 the opinion that it is identical with the latter. It is 

 characterized by globular and spherical, 12.9— 

 22.5 jj.. sporangia, 10-23.5 /x long exit tubes, and 

 spherical, 11— 13/i, smooth, hyaline oospores. 



.1 uei/listes miurii Skvortzow is possibly identical 

 to de Wildeman's species also. The author is ac- 

 cordingly listing it as a synonym and presenting fig- 

 ures of its thallus and resting spores (figs. 38-10). 

 As Miss Berdan has pointed out, the infection hy- 

 phae which Skvortzow figured may be nothing more 

 than exit tubes for the emission of the zoospores. 

 Until the presence of eonidia and direct infection by 

 hyphae have been demonstrated, Skvortzow's spe- 

 cies will remain a doubtful species of either dncy- 

 listes or Mysocytium. 



M. ZOOPHTHORUM Sparrow, 1936. .lour. Linn. Soc. 

 London, Bot. 50: 461. PI. 19, figs. 1-14. 



Thallus rarely branched, constricted or uncon- 

 stricted, septations narrow and inconspicuous, seg- 

 ments .5-17 ju. in diameter, variable in length. Zoo- 

 sporangia irregular, sac-like and lobed with a single 

 short exit tube. Zoospores 6— 7 fi X 10-11 /u.; par- 

 tially or wholly delimited within the sporangium, 

 emerging in succession, and forming a subspherical 

 mass at the mouth of the exit tube, which soon sepa- 

 rates into irregular segments. Sexual fusion through 

 a pore; oospores hyaline, smooth, thick-walled, 

 spherical, 12-15 /v.. with a large refractive globule; 

 germination unknown. 



Parasitic in rotifers and rotifer eggs in England 

 and Denmark. 



Sparrow was uncertain about the generic position 



of this species. In some respects it resembles re- 

 duced thalli of M. vermicolum, while in other in- 

 stances the tubular, contorted segments are reminis- 

 cent of /.. pygmaeum. In sexual reproduction, how- 

 ever, if is like Mysocytium. More recently ('39) 

 Sparrow has pointed out its similarity to L. oophi- 

 Iiiiii which also parasitizes rotifer eggs. The pOSSi' 



