56 



THE SIMPLE HOLOCARPIC BIFLAGELLATE PHYCOMYCETES 



According to Dangeard, the structure and activ- 

 ity of Euglena polymorpha are not greatly affected 

 at first by the presence of the parasite, and in ex- 

 ceptional cases of monoinfection this host may con- 

 tinue its normal activities even after the parasite is 

 mature. The plastids may remain green and un- 

 changed, except for a reduction in size, up to the 

 time of sporulation (figs. 16, 17). In instances of 

 heavy infection, however, the injurious effects may 

 appear sooner. As the parasites develop and ma- 

 ture the starch grains become corroded, the chloro- 

 plasts turn lighter in color, and the cytoplasm be- 

 comes reduced in quantity. The vacuome, stigma, 

 and nucleus, on the other hand, remain normal for 

 a longer time. The initial effect on the nucleus is 

 an increase in chromaticity as densely stainable 

 rods and fragments appear in the reticulum. Later 

 the nucleus decreases in size and finally disinte- 

 grates. Like the remainder of the host cell it does 

 not enlarge or divide because of the presence of the 

 parasite. Mitchell also reported that the parasite 

 has no toxic effect on E. caudata. No differences in 

 activity could be detected in infected individuals, 

 although some of them were so crowded with para- 

 sites that little or no green color was visible. In E. 

 viridis, on the other hand, infected specimens were 

 nearly always rounded, and in fixed and stained 

 preparations early degeneration of the nucleus and 

 chromatophores was evident in such individuals. In 

 the late stages of development the parasite was often 

 envoloped by a mass of degenerating cytoplasm, in- 

 cluding traces of the host nucleus and plastids. 



Pseudosphaerita includes at present P. Euglenae 

 and possibly another species, P. radiata comb. nov. 

 .However, the reports of Pumaly ('27) and Cejp 

 ('35) that Sphaerita endogena and S. dang ear dii 

 have biflagellate zoospores suggest that additional 

 species exit. It is equally possible that Sphaerita 

 may have biflagellate zoospores and does not differ 

 fundamentally from Pseudosphaerita. The parasite 

 of E. sanguinea described by Niigler (11) as P. 

 Euglenae probably does not relate to this species be- 

 cause it develops long exit tubes like Pseudolpidium 

 Sphaeritae. The taxonomic position of Pseudo- 

 sphaerita and its relation to other genera with bi- 

 flagellate zoospores is very uncertain at present. 

 Dangeard ('95) first regarded it as a member of 

 simple olpidiaceous chytrids closely related to 

 Sphaerita, but in 1933 he created a separate family, 

 Pseudosphaeritaceae, for it among the Archimyctes 

 because of its characteristic type of development. 

 Mitchell included the species which he studied in the 

 Sporozoa under the Haplosporidia. 



P. EUGLENAE Dangeard, 1895. I.e., fig. 9. 1933, ibid. 

 25: 30. PI. 4, figs. 3-16. 



Zoosporangia solitary or numerous, oval, spheri- 

 cal, elongate, coiled, or slightly irregular, hyaline 

 and smooth, forming 64 to 128 zoospores. Zoospores 

 pyriform, 2.5-3^ X 6/*; flagella 2.5 and 7 /x long 

 respectively. For further details see the generic de- 

 scription above. 



Parasitic in Euglena viridis and E. pol umorpha 

 in France (Dangeard, I.e.); E. caudata in Georgia, 

 U. S. A. (Mitchell, I.e.). 



This species is possibly the parasite with pyri- 

 form biflagellate zoospores which Stein (1878. Abt. 

 Ill, 1. PI. 20, fig. 21) figured in E. viridis in Ger- 

 many. He also illustrated parasites with biflagellate 

 zoospores in Chlamudomonas alboviridis (PI. 14, 

 figs. VI 4-14) and C. pulvisculus (PI. 15, fig. 36), 

 but since the flagella are posteriorly attached it is 

 doubtful that these parasites relate to Pseudospha- 

 erita. 



P. RADIATA (Dangeard) comb. nov. 



Sphaerita radiata Dangeard, 1890. Le Bot. 2: 54. PI. 2, 



fig. 20. 



Zoosporangia solitary or up to 3 in a cell, hyaline, 

 smooth, oval and egg-shaped, size unknown; lib- 

 erated or expelled to the outside by the rupture of 

 the host cell. Zoospores hyaline with a refractive 

 globule, oval and elongate, isoeont (?), size un- 

 known ; liberated by the breakdown of the sporan- 

 gium wall. Resting spore unknown. 



plate 14 

 (Figs. 2-5 after Dangeard, '95; figs. 1, 6-8 after Dan- 

 geard, '33; figs. 28-31 after Dangeard, '90; figs. 19-27 

 after Mitchell, '28.) 



Pseudosphaerita Euglenae 



Fig. 1. Biflagellate heterocont zoospores with flagella 

 inserted in a small depression near the anterior end; 

 shorter flagellum directed forward. 



Fig. 2. Uninucleate oval parasite (Sphaerita sp. ?) in 

 E. viridis. 



Fig. 3. Multinucleate coiled thallus. 



Fig. 4. Cleavage stages (?) of multinucleate thalli. 



Fig. 5. Euglena polymorpha with 17 uninucleate para- 

 sites which have apparently developed from zoospores 

 liberated within the host cell. 



Fig. (i. Uninucleate parasites slightly larger. 



Figs. 7, 8. Uni- and multinucleate parasites. 



Figs. 9-15. Stages in the division of the parasites fol- 

 lowing each mitosis. 



Fig. 16. A multinucleate parasite shortly before spo- 

 rogenesis. 



Fig. 17. Sporangium with fusiform zoospores. 



Fig. 18. Zoospores liberated within host cell. 



Fig. 19. Euglena caudata with one uninucleate thallus. 



Figs. 20-22. Successive stages of growth and division 

 of the thallus into spores in E. caudata. 



Fig. 23. Two uninucleate thalli (Sphaerita dangeardii 

 ?) in E. viridis. 



Fig. 24-26. Stages in the development of a multinu- 

 cleate thallus in E. viridis. 



Fig. 27. Sporangium filled with spherical and oval 

 spores. 



Pseudosphaerita (?) radiata 



Figs. 28, 29. Biflagellate iso- and heterocont and uni- 

 flagellate zoospores. 



Fig. 30. Cryptomonas ovata with two small parasites. 



Fig. 31. Cryptomonas ovata with a large parasite in 

 which the refractive globules are radially oriented. 



