12 



^-10 



—-11 



-^12 



13 



Fig. lo. Simplest type of movement of flagellum of Monas during rapid 

 forward movement, a, 1-7. Successive stages in preparatory stroke. Note the 

 flexure begins at the base and spreads to the tip. b, 8-13. Successive stages 

 in the effective stroke. Note the rigidity of the flagellum. The arrow indicates 

 the direction of movement of the organism. After Krijgsman. 



Fig. II. 



Fig. 12. 

 Fig. 1 1 . Peranema. a, Slow forward movement with undulations restricted 

 to the tip of the flagellum. 6, Rapid forward movement with undulations 

 along the whole length of the flagellum. After Verworn. 

 Fig. 12. a, Flagellum of Trachelomonas (Euglenoidina) showing axial filament 

 and sheath, b. Transverse section of the flagellum. After Doflein. 



