THE MASTIGOPHORA 



123 



either wholly or partly withdrawn into the protoplasm of the cell. It 

 is occasionally so small and inconsiderable that, as in Phalansterium, 

 it can have little or no use (Fig. 67). Again, it may be fully or even 

 twice as long as the body. In shape it is either like a bowl or else 

 like a truncated cone (Fig. 68, A, C). There 

 may be two of the collars, one within the other 

 (Diplosiga Frenzel, B). Biitschli described 

 a vacuole which appeared to him to move 

 rapidly around the base of the collar and to 

 disappear for a short time when a food particle 



Fig. 68. Types of collars. 

 A. Codosiga pulcherrimus Jas. Cl. [J. CLARK.] B. Dip- 

 losiga socialis Frenz. [FRENZEL.] C. Salpingasca marinus 

 Jas. Cl. [J. CLARK.] 



69. A Choanoflagellate 



type. [FRANCE.] 

 c, collar; m, swinging mem- 

 brane. 



is taken in. Entz ('83) and France ('94) claim, however, that this 

 "mouth-opening" is not a vacuole at all, but the edge of a swinging 

 membrane. According to their view the collar is not a continuous 

 structure with an unbroken wall, but is like a conical roll of paper 

 with a free edge capable of motion (Fig. 69). 



