so 



THE SIMPLE HOLOCARPtC BIFLAGELLATE PHYCOMYCETES 



curved exit tubes which may project considerably 

 beyond the surface of the host cell or extend through 

 adjacent cells. Zoospores heterocont, oval, pyriform, 

 4 X 6 ft, and slightly bean-shaped ; hyaline with 

 several small refractive granules and a contractile 

 vacuole ; emerging singly, fully developed, and 

 swimming directly away, or emerging and lying in 

 a mass for a few minutes at the mouth of the exit 

 tube before becoming amoeboid and flagellate and 

 swimming away; flagella lateral (?), shorter flagel- 

 lum extending forward and the longer one backward 

 in swimming. Resting spores hyaline, smooth, oval, 

 egg-shaped or spherical, 30-10 p., thick-walled with 

 a large refractive globule ; companion or male cells 

 1 to 5 in number, hyaline, smooth, oval or spherical. 

 16.8—21.6 fx; resting spore transformed directly into 

 a zoosporangium with an exit tube in germination. 



Parasitic in Spirogyra sp., Mougeotia sp., and 

 Mesocarpus sp., in Germany (Zopf, I.e.; Fisch, 

 I.e.; Minden, '11); Spirogyra sp., in Hungary 

 (Scherffel, '25); Spirogyra sp., in Belgium (de 

 Wildeman, '90, '91, '96), Roumania (Constanti- 

 neanu, '01), India (Butler, '07; Butler and Bisby, 

 '31), Japan (Tokunaga, '33), causing no or only 

 slight hypertrophy of the host cell. The writer also 

 has frequently observed this parasite in Spirogyra 

 sp., in the vicinity of New York. 



Fisch and Zopf, among the early workers, de- 

 scribed the zoospores as uniflagellate, and for this 

 reason Minden included this species in his new 

 genus, Pseudol pidiopsis. Scherffel's observations, 

 however, leave no doubt about the number of flagella, 

 and Zopf s species may now be returned to the genus 

 Olpidiopsis. Obviously the previous investigators 

 had failed to observe the second flagellum. Fisch's 

 Pleocystidium parasiticum is included here as a 

 synonym of Zopf's species, since it occurs in the 

 same host and appears to have the same structure 

 and type of development. Fischer and Minden re- 

 garded both species as distinct because of the pres- 

 ence of up to five companion cells on the resting 

 spores of P. parasiticum, but de Wildeman found up 

 to four male cells per resting spore in O. schen- 

 kiana also. In view of the variations which Maurizio, 

 Barrett, Diehl, McLarty, Shanor and others have 

 observed in other species of Olpidiopsis, the number 

 of companion cells present is a questionable diag- 

 nostic character. 



O. ELLIPTICA (Schroeter) Fischer, I.e., p. 41. 



Diplophysa elliptica Schroeter, 1886. Cohn's Krvpt'fl. 



Schlesiens 3: 196. 

 Pseudolpidiopsis elliptica (Schroeter) Minden, I.e., 



p. 260. 



Zoosporangia and zoospores unknown. Resting 

 spore obliquely ellipsoid, slightly less in diameter 

 than the host cell, and covered with fine, scattered 

 spines; companion or male cells slightly smaller 

 than the spores, brown and smooth; germination un- 

 known. 



Parasitic in Mesocarpus sp., in Germany. 



This species has been reported only once, but it 

 is not altogether improbable that other species de- 

 scribed from Mesocarpus may be identical or closely 

 related to it. It is reported to differ from O. schen- 

 kiana chiefly by the presence of spines on the resting 

 spores. 



O. SOROKINII de Wildeman, 1890. Ann. Soc. Beige 

 Micro. 14: 22, fig. 7. 



Zoosporangia solitary, hyaline, smooth, elongate, 

 sac-like or cylindrical with a single short exit tube 

 which ends flush with the surface of the host cell. 

 Zoospores small. Resting spore unknown. 



Parasitic in Tribonema {Conferva) bombycinum 

 in Belgium. 



This is a very doubtful species which de Wilde- 

 man thought might be identical to O. fusiformis var. 

 Oedogoniarum Sorokin. Later in his Census Chytri- 

 dinacarum ('96), however, he listed it as Olpidium 

 sorokinii. Inasmuch as the resting spores are un- 

 known its validity as a member of Olpidiopsis is 

 very questionable. 



O. ZOPFII de Wildeman, 1895. La Notarisia 10: 34. 1896, 

 Ann. Soc. Beige Micro. 20: 25, pi. 1, figs. 1-3, 5-7. 

 Pseudolpidiopsis zopfii (de Wildeman) Minden, I.e., 

 p. 259. 



Zoosporangia solitary or numerous, hyaline, 

 smooth, spherical, egg-shaped or ellipsoid with a 

 single exit tube of varying length which usually pro- 

 jects beyond the surface of the host cell. Zoospores 

 unknown. Resting spores spherical, 16— 22/x, with 

 one or more refractive globules, thick-walled and 

 covered witli numerous stout, broad-based, abruptly 

 tapering spines; companion cells 1 to 3 in number, 

 small, oval, spherical, 12 /t, smooth, hyaline; germi- 

 nation unknown. 



Parasitic in Spirogyra sp., in Luxemburg, causing 

 local swellings, up to twice the normal diameter of 

 the filaments. 



O. FIBRILLOSA de Wildeman, 1895. I.e., p. 34. 1896. 

 Ann. Soc. Beige Micro. 20: 27. PI. 2, figs. 13, 14, 18, 19. 

 Pseudolpidiopsis fibrillosa (de Wildeman) Minden, I.e., 

 p. 259. 



Zoosporangia solitary, hyaline, smooth, oval or 

 ellipsoid, witli a single exit tube more or less broad- 

 ened at the base. Zoospores unknown. Resting spores 

 hyaline, thick-walled, spherical, 20-25 ft, oval, egg- 

 shaped and ellipsoid witli one to several refractive 

 globules ; exospore profusely covered with fine, 

 radially oriented hair-like spines or fibrillae which 

 give it the appearance of a halo; companion cells, 

 1—3, hyaline, smooth, spherical or pyriform, occa- 

 sionally occurring in tandem; germination unknown. 



Parasitic in Spirogyra sp., in Belgium (de Wilde- 

 man, I.e.) and Germany (Minden, I.e.), causing only 

 slight swelling of the host filaments. 



