230 The Sarcodina 



Relationships to the Eumycetozoina are not yet clear and further in- 

 vestigation of the life-cycle is needed. In certain species, meiosis is sup- 

 posed to precede formation of spores (28, 57, 155). For the group as a 

 whole, however, data on gametogenesis and syngamy are inadequate from 

 a cytological standpoint. 



About a dozen genera have been erected, largely on the basis of the 

 arrangement of spores in the spore-masses and the shape of the masses. 

 However, Palm and Burk (105), in preparations of Sorosphaera from one 

 host species, found so much variation in the spore-masses that they 

 questioned the validity of the conventional generic criteria. On this basis, 

 they suggested that six generic names (Clathrosoriis Ferdinandsen and 

 Winge, Ligniera Maire and Tison, Mernbranosonis Ostenfeld and Peter- 

 sen, Ostenjeldiella Ferdinandsen, Sorodisciis Lagerheim and Winge, 

 Spongospora Brunchorst) might be considered synonyms of Sorosphaera 

 Schroeter. Furthermore, the authors suggested the advisability of placing 

 all described Plasmodiophorina in only two genera, Plasmodiophora 

 Woronin and Cystospora Elliott (37). 



Cook (27), on the other hand, recognized the following genera: Plas- 

 modiophora Woronin (29, 91), Spongospora Brunchorst (77, 104), Lig- 

 niera Maire and Tison (26), Sorodisciis Lagerheim and \Vinge (157), 

 Sorosphaera Schroeter (10, 155) and Tetramyxa Goebel. These genera are 

 differentiated partly by the arrangement and form of the spores (27). 

 Spherical spores occur in groups of four without a common membrane 

 in Tetramyxa; ellipsoidal or pyriform spores are grouped in irregular 

 "spore-balls" within a common membrane in Sorosphaera; and in hollow 

 spore-balls without a common membrane in Spongospora. A flat "spore- 

 cake," composed of urn-shaped spores, is surrounded by a membrane in 

 Sorodiscus; and in Ligyiiera and Plasmodiophora the spores are neither 

 aggregated nor enclosed in a common inembrane. The taxonomic status 

 of Sporomyxa Leger (125; Fig. 5. 21, J-M), Peltomyxa Leger, Cystospora 

 Elliott, and Trematophlyctis Patouillard has been disputed. According to 

 Cook (27), these genera do not belong in the Plasmodiophorina. 



Suborder 3. Eumycetozoina. The Eumycetozoina (Euplasmodia) in- 

 clude several hundred species of "slime-molds." The mature stage is a 

 migratory plasmodium which reaches a length of several inches to a foot 

 or more. Examined microscopically, the plasmodium in such types as 

 Physarum shows many channels of various sizes. Through the channels 

 flows a liquid containing many granules, the direction of flow being 

 reversed at intervals (92). As the plasmodium moves, vessels may be re- 

 sorbed in some areas and formed anew in others. The cytoplasm may be 

 hyaline, or with inclusions and pigments, may be white or various shades 

 of violet, blue, green, yellow, orange, red, and brown. Unfortiuiately, 

 these colors vary so much, under both natural and experimental condi- 

 tions, that they are not thoroughly reliable as taxonomic characteristics 



