General Morphology of the Protozoa 5 



tions are permissible for sessile, floating, swimming, and creeping types. 

 Floating types, free from the usual stresses of locomotor activity, often 

 approach a spherical form. Active swimmers are usually elongated, with 

 a major axis more or less parallel to the path of locomotion. Creeping 



Fig. 1. 2. AC. Gonium sociale: side view (A); surface view (B); colony 

 with superficial continuous matrix (C); x900 (after Pascher). D, E. Gonium 

 sp., portions of colonies showing supposed protoplasmic connections impreg- 

 nated with silver; x760 (after Klein). F. Syncrypta volvox; x580 (after Stein). 

 G. Protoplasmic connections of somatic flagellates in Volvox; xl800 (after 

 Janet). 



forms are frequently flattened and may show differentiated dorsal and 

 ventral surfaces. Sessile ciliates and flagellates are often more or less 

 conical, attached to the substratum directly or by a secreted stalk. 



In individual Protozoa, form of the body may be maintained by a 

 thickened cortex (the differentiated outer zone of cytoplasm), by various 



