RHIZOPODS, ACTINOPODS, SLIME MOLDS, SPOROZOA 89 



areas of presumptive cell membrane in plasmodia undergoing 

 sclerotization (compartmentalization induced by drying or other 

 rigors) are seen as rows of vesicles. Nuclei in Physarum are 

 rounded and contain many discrete dark granules plus one to 

 several round nucleoli. Mitochondria are microtubular. 



Wohlfarth-Bottermann (1959a), studying plasmodia oiDidymhim 

 nigripes, found that the presumably gelated areas are more compact 

 in cytoplasmic texture and relatively poor in vesicular elements; 

 internally such strands contain abundant fine tubules and vesicles, 

 mitochondria, and a more diffuse matrix. In ripe spores the 

 cytoplasm is extremely dense and uniformly granular; mito- 

 chondria appear unusually large and only a few vesicular struc- 

 tures with dense contents are present. In the germinating spore, 

 the cytoplasm is loose in texture with many vesicles and abundant 

 granular membranes. Wohlfarth-Bottermann's interpretation of 

 these changes relative to sol-gel transformations is discussed above 

 (p. 77). 



Subphylum Sporozoa 



The enormous assemblage of obligate symbiotes commonly 

 referred to as sporozoa includes several probably unrelated series. 

 Grasse (1952, 1953) places them in two subphyla: the Sporozoa, 

 including the classes Gregarinomorphea, Coccidiomorphea, and 

 Sarcosporidea, characterized by a vermiform, mobile sporozoite 

 as the initial stage in the life cycle; and the Cnidosporidia, con- 

 taining only three orders, whose initial developmental stage is an 

 ameboid sporoplasm. A number of genera of undefinable 

 affinities is loosely appended to the Sporozoa. 



The existence of flagellated male gametes among the sporozoa 

 is considered evidence of their flagellate ancestry ; kinship with 

 euglenoids, dinoflagellates, and bodonids has been suggested (see 

 Grasse, 1953), but clear-cut evidence is lacking, as is to be 

 expected after a long history of symbiosis. 



In addition to their importance as agents of disease in man and 

 domestic animals, the sporozoa are of considerable biological 

 interest because of their remarkable adaptations to symbiosis : the 

 complexity of their life cycles is matched by few other kinds of 

 single-celled organisms and commonly includes stages in which 

 they live exclusively within the cells of their hosts. Questions 



