54 



THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES 



(?), shorter flagellum extended forward in swim- 

 ming; emerging singly and fully developed and 

 swimming directly away, or lying quiescent in a 

 globular mass for a few moments at the mouth of the 

 exit tube. Resting spores unknown. 



The history of this genus has been discussed in 

 relation to Olpidiopsis and need not be repeated 

 here. As noted previously it is retained only as a 

 temporary expedient for three species with biflagel- 

 late zoospores in which no resting spores have yet 

 been reported. It is not improbable as McLarty and 

 Shanor have suggested that two of the species will 

 eventually be included in Olpidiopsis, while the 

 third one may possibly prove to be related to Rozel- 

 lopsis or Woronina. 



Zoospore germinating and infection of the host 

 have been described only for P. deformans, so that 

 an account of the early developmental stages must 

 be based on this species. As is shown in figure 180 

 the zoospores come to rest on the host, round up, 

 encyst, and later develop conspicuous germ tubes 

 (figs. 185, 186) which penetrate the host wall. As in 

 Olpidiopsis the content of the spore passes through 

 this tube into the host as a naked body, and in all 

 species except P. deformans gives rise to one thallus 

 or sporangium. At first the young parasite is more 

 or less indistinguishable from the host protoplasm, 

 but as the latter is killed and partly consumed the 

 parasite may be readily recognized as a small dense 

 mass in the hypertrophied cells (fig. 181). 



In P. deformans the thallus becomes amoeboid 

 shortly after entering the host cell (fig. 24). It de- 

 velops numerous long, fine (fig. 182) or blunt pseu- 

 dopods (fig. 181) and creeps around in the infected 

 cell. After its nucleus has divided it constricts and 

 divides as is shown in figure 183. Serbinow's figures 

 further suggest that the large multinucleate amoe- 

 boid thalli also may divide, so that numerous thalli 

 result from a single infection. Whether or not sev- 

 eral meronts are formed by a process of schizogony 

 as in the Plasmodiophorales is not certain. Multiple 

 infection, however, is not uncommon (figs. 185, 

 186), so that the presence of several thalli in one 

 cell does not mean that they have arisen from a sin- 

 gle infection. The occurrence of single sporangia in 

 a host cell (figs. 187, 188) suggests that the amoe- 

 boid thallus does not always divide and that a zoo- 

 spore may sometimes give rise directly to one spo- 

 rangium. The early developmental stages of P. de- 

 formans are nonetheless suggestive of those of the 

 septigeneous species of RozeUopsis, provided the 

 reports that the thallus of this genus undergoes di- 

 vision are true. Minden was accordingly of the opin- 

 ion that Serbinow's fungus is closely related to gen- 

 era which develop sporangiosori. Unlike Woronina 

 pol i/ci/stis and species of Rozellopsis, the thallus of 

 P. deformans is visually distinguishable from the 

 host protoplasm, and no cross walls separate the re- 

 spective segments of the thallus as in R. septigena 

 and R. simulans. It differs further from other spe- 

 cies of Pseudolpidium by the lack of oily or fatty 



ref ringent material in the developing thalli and spo- 

 rangia, according to Serbinow. 



P. GLENODINIANUM (Dangeard) Fischer, 1893. 

 Rabenh. Krypt'fl. I, 4: 36. 

 Olpidium Olenodinianum Dangeard, 1883. Jour, de Bot. 

 2: 130. PI. 5, figs. 6-10. 



Zoosporangia solitary or up to 4 in a cell, spheri- 

 cal or ellipsoid, size unknown ; hyaline and smooth 

 with a short papillae or exit tube which extends 

 slightly beyond the surface of the host. Zoospores 

 emerging fully formed and remaining quiescent for 

 a few minutes in a globular mass at the mouth of the 

 exit orifice before swimming away ; spherical at first, 

 later becoming oval or ellipsoid, size unknown; 

 flagella laterally inserted, shorter flagellum extend- 

 ing forward and longer one projecting backward in 

 swimming. Resting spores unknown. 



Parasitic in Glenodinium cinctum in France, com- 

 pletely killing and destroying flourishing cultures. 



According to Dangeard this species had been fre- 

 quently observed before his time, but its thallus and 

 zoospores were mistaken for germination stages of 

 the hosts as well as those of Ceratium fuscus and C. 

 tripos. 



P. SPHAERITAE (Dang.) Fischer, I.e., p. 36. 



Olpidimm SphaerUae Dangeard, 1889. I.e Bot. 1:51. 



PI. 3, figs. 3-7. 

 Olpidiopsis Sphaeritae (Dang.) Schroeter, 1897. Engler 

 und Prantl, Xat. Pflanzf. I, 1 : 69. 



Zoosporangia solitary or up to 6 in one host cell, 

 hyaline, smooth, spherical, or ellipsoid, size un- 

 known, with a single exit canal which projects far 

 beyond the surface of the host cell. Zoospores small, 

 size unknown, hyaline with one to several refrac- 

 tive granules; flagella laterally (?) inserted, shorter 

 one extending forward in swimming. Resting spores 

 unknown. 



Parasitic in the resting spores of Sphaerita cn- 

 doc/ena in France. 



This species has not been reported since 1889 and 

 nothing further is known about its life history and 

 structure besides the original description of Dan- 

 geard. 



P. DEFORMANS Serbinow, 1907. Scripta Bot. Hort. 

 Imp. Univ. Petrop. 24: -25, 154. PI. 1, figs, 1-13; pi. 4, 

 figs. 16-38. 



Thallus more or less naked, amoeboid, constricting 

 and dividing to form additional thalli. Zoosporangia 

 solitary or up to 11 in a host cell, hyaline, smooth. 

 spherical, 35 p., or elongate and ellipsoid, 14.7— 27 p. 

 X 47.5 (u with a broad elongate, 8 X 15.8/*, exit 

 tube which projects considerably beyond the sur- 

 face of the host cell. Zoospores, hyaline, spherical 

 or oval, 3.15—4.75 p., often changing shape; flagella 

 laterallv inserted; emerging singly, fully developed 

 and swimming directly away. Resting spores un- 

 known. 



