48 



THE SIMPLE HOLOCARPIC MELAGELLATE PHYCOMYCETES 



12) suggests that they are both lateral in position. 

 According to Miss Whiffen, 0. gracile will not in- 

 fect P. torulosum, P. pvlchrum, P. proliferum nor 

 the unidentified Pythium hosts of O. brevispinosa 

 and O. curvispinosa. 



O. CURVISPINOSA Whiffen, 1042. Amcr. Jour. Bot. 

 29:610. Figs. 1, .5, 21. 



Zoosporangia solitary or numerous, spherical to 

 oval, 12-68 fx in greatest diameter, hyaline, smooth 

 or covered by short bristles, with one to three exit 

 tubes. Zoospores with numerous oil globules, elon- 

 gate and somewhat reniform, size unknown; flagella 

 of about equal length and attached near anterior 

 end. Resting spores hyaline, spherical to oval, 17— 

 24 p., containing a large refractive globule sur- 

 rounded by vacuolate protoplasm ; exospore covered 

 by curved spines up to 5 /x in length. Companion or 

 male cell consistently present, hyaline, spherical, 

 or oval, 14-20 p., smooth or with short, closely-set 

 spines; germination unknown. 



Parasitic in Pythium sp., and P. torulosum in 

 North Carolina, U. S. A., causing large terminal or 

 intercalary swellings in the host hyphae. 



O. BREVISPINOSA Whiffen, I.e., p. 610. Figs. 2, 22, 21. 



Zoosporangia solitary or numerous, oval, spheri- 

 cal, 10.6-68.1/1, with one to three exit tubes. Zoo- 

 spores elongate and somewhat reniform with sev- 

 eral oil globules; flagella of about equal length and 

 attached near the anterior end. Resting spores dark 

 brown, spherical to oval, 10.6—15.1 xx, containing a 

 large refractive globule surrounded by vacuolate 

 .protoplasm ; exospore 1.7-2.5 /x thick, covered by 

 short, fine spines up to 3.5 /x in length, endospore 

 .75— 1.32 p. thick; companion cell consistently pres- 

 ent, oval, spherical, 7.1-25.5 /x, smooth or spiny; 

 germination unknown. 



Parasitic in Pythium sp., from Louisiana, 

 U. S. A., causing large terminal and intercalary 

 swellings, up to 125 p in diameter, in the host 

 hyphae. 



This species is limited in host range to an uniden- 

 tified species of Pythium and will not infect P. ros- 

 tratum. nor the host of O. curvispinosa, according to 

 Miss Whiffen's cross inoculation experiments. 



PARASITES OF ALGAE 



O. SCHENKIANA Zopf, 1884. Nova Acta Ksl. Leop.- 



Carol. Deut. Akad. Nat. 47: 168. PI. 15, figs. 1-32. 

 Pleocystidmm parasiticum Fisch, 1884. Sitzb. Phys.- 



Med. Soc. Erlangen 16: 60. Figs. 24-3!). 

 Olpidiopsis parasitica (Fisch) Fischer, 1H92. Raben- 



horst's Krypt'fl. I, 4: 40. 

 Diplophysa schenkiana (Zopf) Schroeter, 1897. Engler 



und Prantl, Die Nat. Pflanzenf. I, 1: 85. 

 Pseudolpidiopsis schenkiana ('/opt') Minden, 1911. 



Krypt'fl. Mark Brandenburg 5: 257. 

 /'. parasitica (Fisch) Minden, I.e., p. 258. 



Zoosporangia solitary or numerous, hyaline, 

 smooth, spherical, oval, ellipsoid, egg-shaped, elon- 

 gate, 21.6-26.4 xi X 30-81.6 it, with one or two 

 stout, short or elongate, up to 60 /x long, straight or 



plate 12 

 O. gracile 



Fig. 123. Mature zoosporangium with 4 exit tubes; ac- 

 companied by a resting spore. Butler, I.e. 



Figs. 124, 125. Pyriform beteroeont (?) zoospores with 

 refractive bodies. Butler, I.e. 



Fig. 126. A large diverticulum with numerous sporangia 

 and resting spores. Butler, I.e. 



Fig. 127. Smooth-walled resting spore. Whiffen, '42. 



O. curvispinosa and O. brevispinosa 

 Fig. 128. Resting spore of O. curvispinosa with long 

 curved spines. Male cell spiny. Whiffen, I.e. 



Fig. 129. Spiny resting spore and male cell of O. brevi- 

 spinosa. Whiffen, I.e. 



O. schenkiana 



Fig. 130. Infection of Spirogyra cell. Zopf, '84. 



Fig. 131. Cellulose plug on cell wall at point of entry of 

 germ tube. Scherffel, '25. 



Fig. 132. Forked germ tube, and young naked vacuolate 

 parasite in host cell. Scherffel, I.e. 



Fig. 133. Young parasite next to larger host nucleus 

 (P. parasiticum). Fisch, '84. 



Figs. 134 to 136. Zoosporangia and emission of zoo- 

 spores. Zopf, I.e. 



Fig. 137. A flagellate amoeboid primary swarmer with 

 contractile vacuole. Scherffel, I.e. 



Fig. 138. Side view of pyriform, beteroeont secondary 

 swarmer with contractile vacuole. Scherffel, I.e. 



Figs. 139, 140. Optical and cross-section views of same. 

 Scherffel, I.e. 



Fig. 141. Early stage in resting spore formation. Zopf, 

 I.e. 



Fig. 142. Resting spore with one companion cell. Zopf, 

 I.e. 



Fig. 143. Resting spore with four companion cells. De 

 Wildeman, '96. 



Fig. 144. Similar resting spore (P. parasiticum) Fisch, 

 I.e. 



Fig. 145. Germination. Only one flagellum shown on 

 zoospores. Zopf, I.e. 



Figs. 146 to 148. Zoosporangium and resting spores of 

 O. zopfii. De Wildeman, I.e. 



Fig. 149. Resting spore of O. fibrillosa. Spines not 

 shown. Two male cells in tandem. De Wildeman, I.e. 



Fig. 150. Same with fibril-like spines. De Wildeman, I.e. 



Fig. 151. Resting spore of O. appendiculata. De Wilde- 

 man, I.e. 



O. Oedogoniorum 

 (All figures after Scherffel, '25) 



Fig. 152. Mature vacuolate zoosporangium. 



Fig. 153. Isocont primary swarmer. 



Fig. 154. Cystospores. 



Figs. 155, 156. Resting spores in elongate hyaline vesi- 

 cles with attached companion cells. 



O. Hiccioe 



Fig. 157. Empty zoosporangium in a rhizoid. 

 Fig. 158. Anteriorly biflagellate, beteroeont zoospores. 

 Figs. 159, 160. Resting spore with companion cell, and 

 elongate parthenogenetic (?) spore. 



