136 



BIOLOGY OF THE PROTOZOA 



There are, however, abundant variations in size, number, and 

 position of fla^ella in the celh When there is l)ut one it usually 

 emerges from a pit or funnel-shaped opening at the anterior end of 

 the cell (flagellum fissure). When two are present they may be 

 equal in size and length (e.g., ChUomonas paratnecium) , or one may 

 be considerably thicker and longer than the other (heteromastigote 

 types). Both may be directed forwards as in Amphimonadidte 

 (Fig. 59, p. 117), or one may be directed forward, the other back- 

 ward, as in Bodo, Anisonema, etc. In such cases the posteriorly 

 directed flagellum (trailing flagellum or Schleppgeissel) appears to 



Fig. 70.- 



-Dinofiagellates with reduced epithecse. A, B, Side and ventral views of 

 Anrphidinium herdmanni Kof. ; C, Glenodiniutn sp. (After Calkins.) 



act as a runner upon which the cell body glides, and has little to do 

 with the actual locomotion of the animal (Fig. 69). 



Flagella var^- in length from extremely short fibers in Noctihica 

 milians and some species of EugJeita to forms two or three times 

 the length of the body, but the majorit.y are about as long as the 

 body. In the Dinoflagellata they are particularly remarkable. 

 Here there are two flagella, one of which extends freely into the 

 water, while the other girdles the body in a transverse groove or 

 annulus which is characteristic of these flagellates, where it gives the 

 impression of many cilia (Fig. 70). The earlier figures of the Dino- 



