17 



Figure 3. Structure of one of the most complex of the Protozoa, 

 Diplodinium ecaudatum Fiorentini, after Sharp (1914). A, mouth; B, 

 oral cilia; C, adoral membranelles ; D, oesophagus; E, oesophageal re- 

 tractor strands; F, ventral skeletal lamellae; G, entoplasm; H, ecto- 

 plasmic boundary layer; I, cuticle; J, caecum; K, rectum; L, rectal 

 fibers; M, ectoplasm; N, posterior contractile vacuole; O, micronucleus ; 

 P, suspensory fibers; Q, macronucleus ; R, anterior contractile vacuole; 

 S, posterior ciliary roots; T, dorsal membranellae ; U, operculum; V, 

 motor mass; W, circumoesophageal ring. 



complex; they may properly therefore be called unicellular 

 organisms. 



But whatever the facts as to their simplicity or complex- 



