76 



PLASMODIOPHORALES 



uninucleate, but the abnormal ones may possess 2 

 to 30 nuclei scattered about or aggregated in groups. 

 The wall of the spore is hyaline, streaked, and thick, 

 and by treatment with iodine and sulphuric acid it 

 assumes a bluish tint, indicating the presence of 

 cellulose. 



A second species, S. Tenebriones, was found by 

 Reitschel ('36) in the fat bodies, ovaries, and con- 

 nective tissues of the larvae and imago of Tenebrio 

 molitor. The life liistory and development of this 

 species (fig. 18—25) are similar to tliose of S. Scauri 

 with the exception that the thalli become larger and 

 undergo cleavage at maturity. At the time of sporu- 

 lation they may contain considerably more than a 

 hundred nuclei and are enveloped by a thin mem- 

 brane. The protoplasm cleaves into uninucleate seg- 

 ments (fig. 22, 23) which later round up and become 

 the resting spores as in Plasmodiophora, The soral 

 membrane disintegrates shortly thereafter and frees 

 the spores. These are usually uninucleate (fig. 24'), 

 rarely binucleate (fig. 2.5), hyaline, smooth, and 

 measure 9—13 fi by 4.5—7 fj.. In neither of these spe- 

 cies have spore germination, zoosporangia, and zoo- 

 spores been observed. 



Leger believed that Sporomyxa may be closely re- 

 lated to Sapphiia because of its method of sporula- 

 tion. Maire and Tison (09) regarded it as of doubt- 

 ful affinity with the Plasmodiophorales and stressed 

 lack of promitosis in nuclear division as a distinctive 

 character. Fitzpatrick ('30) and Cook ('33) ex- 

 cluded it on the grounds of its habitat and ellipsoidal 

 isolated resting spores, but as Palm and Burk ('33) 

 have pointed out, "the circumstance that it attacks 

 an animal host could hardly be taken as a serious 

 objection." However, our knowledge of its life cycle 

 and cytology seems hardly sufficient to justify its 

 inclusion in the Plasmodiophorales at the present 

 time. 



PELTOMYCES 



Leger, 1909. C. R. Acad. Sci. Paris 149: 239. 



Leger founded this genus to include three para- 

 sites, P. hi/alinus, P. Blatella, and P. Forficulae, 

 which occur in the malpighian tubes of Olocrates, 

 Blatella, and Forficula species. His description of the 

 genus was based primarily on the development and 

 life cycle of P. hijalinus, apparently the oiil}^ species 

 which he studied in detail. This species makes its 

 appearance in the epithelium as a small, 2 //., uninu- 

 cleate globular body. Its nucleus multiplies mitoti- 

 cally, and the parasite soon grows into a multinucle- 

 ate disc-shaped plasmodium which subsequently un- 

 dergoes schizogony and forms a large number of 

 small, 2-3 /x, uninucleate sporonts. 



At the conclusion of schizogony the sporogonic 

 phase begins. Each sporont increases in size while 

 its nucleus divides mitotically several times. Two 

 types of nuclei are thus formed: small, densely- 

 stainable somatic nuclei without membranes, and 

 larger, normal-looking gametic nuclei with well- 



defined membranes. The former nuclei disintegrate, 

 while the latter become enveloped in a small spheri- 

 cal mass of cytoplasm and are soon transformed into 

 bowl-shaped, 2 jj., gametes. These fuse in pairs after 

 their nuclei have undergone a chromatic reduction, 

 and this is soon followed by karyogamy. The zygotes 

 or incipient diploid resting spores formed in this 

 manner develop a wall and assume a cylindrical, 

 3X9/^, shape. Each mature sporont thus encloses 

 within its tliin wall 4 to 8 spores arranged side by 

 side and looks like a sporangium. The gametes in 

 the sporonts which fail to fuse develop into par- 

 thenogenetic spores of about half the size of the dip- 

 loid spores. In some cases prematurely formed spo- 

 ronts, instead of producing gametes, form small en- 

 dogenous cells which escape from the sporonts and 

 behave as schizozoites in the host. Leger did not 

 illustrate any of tliese species, and his account of 

 their development is brief and fragmentary. Zoo- 

 spores, sporangia, and cystosori are unknown in 

 Peltomyces. 



CYSTOSPORA 



Elliott, 1916. Delaware Agr. Exp. Sta. Bull. 

 114: 15. 



(plate 15, FIG. 26-47) 



This genus was created b}' Elliott for a myxomy- 

 cete-like organism, C. batata, which is reported to 

 cause "soil rot," "pit " or "pox" of sweet potatoes in 

 the United States. Elliott placed it in the Plasmodio- 

 phorales, but its inclusion here is very doubtful, if at 

 all warranted. In fact, some workers (Manns and 

 Adams, '25) have expressed doubt about tlie ex- 

 istence of an organism of this type and asserted that 

 some of the stages figured by Elliott may be nothing 

 more than products of disturbed metabolism of the 

 sweet potato. Tabenhaus (18), however, reported 

 tliat he was able to grow tliis organism in pure cul- 

 ture on sweet potato agar made up according to 

 Elliott's formula. He further confirmed Elliott's ac- 

 count of the life cycle of C. batata. 



According to these workers, the zoospores are 

 small, 1—2 ft X 1-5-3 /x, globose with tapering ends 

 and possess a short flagellum, but it is not evident 

 from their descriptions whether the flagellum is an- 

 terior or posterior. The zoospores are nonetheless 

 produced in great numbers (fig. 43, 44) and may re- 

 main active from 1 to 7 days in rare instances, ac- 

 cording to Tabenhaus. The period of activity, how- 

 ever, is usually short, often less than half an hour. 

 The zoospores may sometimes fuse in pairs and form 

 round zygotes which later become amoeboid ( fig. 

 26, 27). According to Elliott, they bore through the 

 cell wall and infect the host as amoebae, but Taben- 

 haus reported that infection may also take place by 

 means of a plasmodium. The nuclei of the young par- 

 asite divide mitotically and simultaneously (fig. 28, 

 29, 32), but unfortunately Elliott's figures are so 

 small and poorly drawn that it is impossible to deter- 



