The Sarcodina 227 



Order 2. Mycetozoida 



The mature stage of the Mycetozoida^ is either a large plasmodium 

 or a pseudoplasmodium. On the basis of differences in morphology and 

 life-history, three suborders may be recognized: (1) Acrasina ("Acra- 

 siales"), in which the structural unit is the uninucleate stage, although 

 pseudoplasmodia may be formed by aggregation of myxamoebae with- 

 out cytoplasmic fusion; (2) Plasrnodiophorina ("Plasmodiophorales"), 

 parasites which are plasmodia at maturity but do not produce sporangia; 

 (3) Eumycetozoina (Euplasmodida, "Myxogastres"), the typical free- 



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V>-''^A 



PJL 



Fig. 5. 20. A, B. Dirtyostcliinn inucoroides Brefeld (after Schuckmann): 

 active amoeboid stage with ingested bacteria, x440 (A); portion of pseudo- 

 plasmodium showing spindle-shaped organisms, x440. C-M. Dictyosteliiim 

 discoideuni Raper (after Bonner): C-I. Successive stages in development of 

 a pseudosporangium from a pseudoplasmodium; diagrammatic. J. Pseudo- 

 sporangium, almost mature, showing basal disc, stalk, and spores; schematic, 

 xl40 approx. K-M. Diagrams illustrating changes in position of "cells" 

 during development of a pseudosporangium (M) from a pseudoplasmodium 

 (K). KEY: b, basal disc "cells"'; s, spore "cells"; 1, 2, 3, stalk "cells" of three 

 different regions. 



^ Detailed discussions of the Mycetozoida will be found in several monographs (46, 

 84, 86) and modern data have been reviewed by Martin (89). 



