CHYTRIDIALES 63 



at maturity a naked, multinucleate plasma which tends to fill 

 the host cell. It may assume a membrane and function directly 

 as a multispored sporangium, or it may break up while yet 

 naked into a number of uninucleate bits each of which becomes 

 invested in a wall. Each of these bits is comparable to the spore 

 of Sorosphaera and on germination frees two to four zoospores. 

 Maire and Tison regard Rhizomyxa as a complex of several organ- 

 isms, and feel that this phase is probably merely S. verrucosa. 

 The multispored sporangium may be that of an Olpidium. 



More recently Nemec has described two genera, SoroJpidium 

 Nemec (1911 c) and Anisomyxa Nemec (1913 a), which should be 

 given consideration in connection with Rhizomyxa. In the 

 first, based on S. hetae Nemec, found in the living cortical cells 

 of Beta vulgaris, the thallus persists to maturity as a naked 

 multinucleate protoplast, and then is said to become invested 

 in a thin membrane. Fragmentation finally results in the forma- 

 tion of a sorus of spores each of which later frees one to several 

 zoospores. (See Guyot, A. L., Rev. Path. Veg. et Ent. Agric., 

 14 : 176-183, 1927.) 



In Anisomyxa, based on A. plantaginis Nemec, found in the 

 roots of Plantago, a similar situation exists. The individual 

 sporangium may be relatively large, and frees a considerable 

 number of spores. A common soral envelope was not observed. 

 Nemec's accounts do not carry conviction, and leave us in doubt 

 concerning essential points in the life cycle in both genera. If 

 he has not misunderstood his material these forms seem to be 

 intermediate between Plasmodiophora and the Synchytriaceae. 

 They should be studied further, 



4. Sorodiscus Lagerheim & Winge (Winge, 1912). 



In 1870, Kareltschikoff and Rosanoff described pecuhar flat 

 plate-hke bodies which they found in the cells of Callitriche 

 autumnalis. These bodies were later observed by Lagerheim in 

 C. vernalis, and were recognized by him to be spore aggregations 

 of one of the Plasmodiophoraceae. In 1912, Winge, working 

 over Lagerheim's material, made these the basis of the new genus 

 Sorodiscus and the new species S. callitrichis Lagerheim & 

 Winge. 



The spore aggregations are flattened plates of uniform thick- 

 ness but of var>dng outline and diameter depending on the size 

 and form of the host cell. The plate consists of two layers of 



