MYCETOZOA 433 



Genus Ceratiomyxa Schroter (Fig. 181, 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. Development of 

 Dictyostelium discoideum (Raper, 1940) ; food habits and distribution 

 of Dictyostelium (Singh, 1947, 1947a). 



Phytomyxinea Poche 



These organisms which possess a large multinucleate amoeboid 

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

 onomy (Palm and Burk, 1933; Cook, 1933). 



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. 182, a). The small (haploid) spore (6) gives rise to a myxoflagel- 

 late (c-f) which penetrates the host cell. The organism grows in size 



6 



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Fig. 182. 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 young parasites, X400; 

 h, an older parasite, X400 (Nawaschin). 



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. Morphology (Jones, 1928) ; cy- 

 tology (Milovidov, 1931). 



P. brassicae W. (Fig. 182). In Brassica spp. 



