MYCETOZOA 



341 



Genus Ceratiomyxa Schroter (Fig. 158, m, n) 

 Suborder 2 Sorophora Lister 



Pseudoplasmodium incomplete; myxamoeba of limax-form 



Family 1 Guttuliniidae 



Pseudoplasmodium complete; myxamoeba with short pointed pseudo- 

 podia Family 2 Dictyosteliidae 



The Proteomyxa and the Mycetozoa as outlined above, are not 

 distinctly defined groups. In reality, there are a number of forms 

 which stand on the border line between them. 



Phytomyxinea Poche 



These organisms which possess a large multinucleate amoeboid 

 body, are parasitic in various plants and also in a few animals. 



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Fig. 159. Plasmodiophora brassicae. a, root-hernia of cabbage; b, a 

 spore, X620; c-e, stages in germination of spore, X620; f, myxamoeba, 

 X620 (Woronin); g, a host cell with several j^oung parasites, X400; 

 h, an older parasite, X-100 (Nawaschin). 



Genus Plasmodiophora Woronin. Parasitic in the roots of cabbage 

 and other cruciferous plants. The organism produces knotty enlarge- 

 ments, sometimes known as "root-hernia," or "fingers and toes" 

 (Fig. 159, a). The small (haploid) spore (b) gives rise to a myxoflagel- 

 late (c-/) which penetrates the host cell. The organism growls in size 

 and multiplies (g, h). The Plasmodium divides into sporangia. Flagel- 

 lated gametes that develop from them fuse in pairs, giving rise to 

 diploid zygotes. These zygotes develop further into plasmodia in 

 which haploid spores are produced. 



P. brassicae W. (Fig. 159). In Brassica spp. 



Genus Sorosphaera Schroter. Parasitic in Veronica spp. 



Genus Tetramyxa Goebel. In Ruppia, Zannichellia, etc. 



Genus Octomyxa Couch, Leitner and Whiff en. In Achlya glomerata. 



Genus Sorodiscus Lagerheim and Winge. In Chara, Callitriche, etc. 



