86 



PLASM ODIOPH OR ALES 



described the zoospores as spherical (fig. 3, I) with 

 two anterior flagella which lasli back and forth in 

 breast-stroke fasliion in swimming. These workers 

 were non-committal as to the relative lengths of the 

 flagella, but most of the figures show them to be equal 

 in length. One of their figures (fig. 3), however, 

 shows flagella of unequal length. If the zoospores are 

 anteriorly biflagellate, as Cook and Nicholson con- 

 tended, and heterocont as Fischer reported, they do 

 not difter fundamentally from those of the Plasmo- 

 diophorales. In view of the wide differences in ob- 

 servations it is not altogether improbable that what 

 is now called W. polycystis may relate to more than 

 one organism or species. Further critical studies on 

 this species are therefore highly essential. 



So far schizogony has not been reported in Jf. 

 polyci/stis, and nothing is known about the type of 

 nuclear divisions in the vegetative thallus. This para- 

 site has never been studied critically from fixed and 

 stained material, and it is not improbable that fu- 

 ture investigations may reveal the occurrence of schi- 

 zogony and "promitotic" divisions. It should be 

 noted in this connection, however, that the sporangia 

 and resting spores of W. poli/ci/slis give a definite 

 cellulose reaction, while those of the Plasmodiopho- 

 rales do not. Furthermore, in germination the content 

 of the zoospore enters the host through a penetration 

 tube, leaving the empty case on the outside of the 

 host cell as in Olpidiopsis, Rosella, etc. In the Plas- 

 modiophorales the zoospores are reported to enter 

 directly. The latter difference may not be important, 

 but the presence of cellulose is fundamentally sig- 

 nificant, according to present-day students of phy- 

 logeny. 



The other species of Woronina, W. glomerata, 

 JV. af/c/regata, W. elegans, and W. asterina, are not 

 well known, and it is difficult to compare them with 

 the Plasmodiophorales. Woronina glomerata para- 

 sitizes J'aucheria and causes septation of the fila- 

 ments without hypertrophy. It forms both sporan- 

 gio- and cystosori, but the resting spores and spo- 

 rangia are not closely aggregated and compact like 

 in 11'. polyci/stis. Motile zoospores have not been 

 illustrated, so that nothing is known about the num- 

 ber, position, and relative lengths of the flagella. The 

 zoospores apparently enter the host directly, divide, 

 according to Zopf ('9-i, p. 54), and form amoebae, 

 which may in turn divide. The amoebae feed on the 

 host i^rotoplasm and engulf starch grains, chloro- 

 phyll granules, etc., whereby they may become quite 

 green in color. This food is held in well-defined vac- 

 uoles, according to Scherffel ('25), and shortly be- 

 fore the parasite fructifies, the extraneous waste ma- 

 terial is extruded as in typical proteomyxean species. 

 The amoebae later unite by fine strands or pseudo- 

 pods and form a reticulate plasmodium, which may 

 completely fill the host cell. The amoebae may sepa- 

 rate again, but at maturity tlie plasmodium cleaves 

 into segments or "Theilplasmodien," each of which 

 becomes a sorus of zoosporangia or resting spores. 

 This division of amoebae and plasniodia is sugges- 

 tive of schizogony in the Plasmodiophorales. The 



resting spores of Jf. glomerata, unlike those of W. 

 polycystis and the Plasmodiophorales, function as 

 zoosporangia in germination and produce numerous 

 zoospores. Because of its type of nutrition, Zopf and 

 Scherffel regarded W . glomerata as an organism 

 with animal and fungal characteristics and included 

 it with tlie zoosporic Myxozoidia or Proteomyxa. It 

 may be noted, however, that W. polycystis also feeds 

 directly upon the host protoplasm by bodily taking 

 in globules of oil, according to Cook and Nicholson. 

 Except for the possession of biflagellate zoospores 

 and an intramatrical holocarpic thallus, the other 

 known genera of the Woroninaceae, with the pos- 

 sible exception of Rosellopsis Karling ('4'2b), do 

 not appear to have much in common with the Plas- 

 modiophorales. In the polysporangiate, septigenous 

 species of Rosellopsis, the thallus has been described 

 as naked and plasmodium-like, and undergoes seg- 

 mentation to form numerous zoosporangia which be- 

 come separated by cross septa in the host. Further- 

 more, in R. simulans the zoospores are anteriorly bi- 

 flagellate and heterocont, according to Tokunga 

 ('33). However, so little is known about the devel- 

 opment and cytology of these species that it is im- 

 possible to draw further comparisons. Tliere are 

 nevertheless striking similarities in the development 

 of the Plasmodiophorales and certain species of the 

 Woroninaceae, particularly W. polycystis, which 

 suggest a close relationship and common origin. Cook 

 ('33), on the other hand, contended that these simi- 



PLATE 16 



Fig. 1, 3. Biflagellate zoospores. Fischer, '83. 



Fig. 3, 4. Anteriorly biflagellate zoospores. Cook and 

 Nicholson, "33. 



Fig. 5, G. Early infection stages. Fischer, I.e. 



Fig. 7. Same. Cook and Nicholson, I.e. 



Fig. 8-10. Amoeboid changes in shape and position of 

 young parasite in host cell. Fischer, I.e. 



Fig. II, 13, 13, 15. Successive stages in develojmient of 

 the parasite and its cleavage into a sporangiosorus. Note 

 local hypertrophy and septation of host hypha. Fischer, I.e. 



Fig. 14. Vacuolate thallus undergoing centrifugal cleav- 

 age. Fischer, I.e. 



Fig. 16. Sporangiosorus. Cornu, '73. According to Couch 

 ('39) this figure relates to P. dioicii. 



Fig. 17-30. Maturation, cleavage, and emission of zoo- 

 spores from a sporangium. Fischer, I.e. 



Fig. 31. Small empty sporangiosorus. Cornu, I.e. 



Fig. ^2-2. Cleavage of thallus into a eystosorus. Fischer, I.e. 



Fig. 33. Mature eystosorus. Cornu, I.e. 



Fig. 34. Septate, locally hypertrophied hypha of Sapro- 

 leffiiid with five cystosori of various sizes and shapes and 

 two emiity sporangiosori. Fischer, I.e. 



Fig. 35. Elongate irregular eystosorus. Cook and Nichol- 

 son, I.e. 



Fig. 36. Variously-shaped resting s))ores from a eysto- 

 sorus. Fischer, I.e. 



Fig. 37, 38. Thick-walled resting spores. Cook and 

 Nicholson, I.e. 



Fig. 39. Germination of eystosorus. Resting spores swell- 

 ing and vesiculating to become zoosporangia. Fischer, I.e. 



Fig. 30. Germination of resting spores. Cook and Nichol- 

 son, I.e. 



