32 



GENERAL CONSIDERATIONS 



an early stage in its life history, a stage corresponding to the period 

 of encystment in Uroleptus, this organism loses its normal form which 

 is assumed under certain feeding conditions (see Kidder, infra, Chap- 

 ter VIII), becomes elongate and cylindrical, and darts about in the 

 medium with unusual speed ( Fig. 12). Soon its mouth and oral mem- 



Figure 11. Glaucoma 

 (Dallasia) frontata Stokes. 

 Vegetative individual. A, 

 anus; BC buccal system; 

 CV, contractile vacuole ; 

 LS ladder system; LU left 

 undulating membrane; M 

 mouth of buccal cavity; 

 MOT, region of motorium ; 

 RU right undulating mem- 

 brane; T, "tongue" in buc- 

 cal cavity. (After Calkins 

 and Bowling, 1929.) 



branes are resorbed and it divides into two cylindrical individuals. 

 These divide into four, the four into eight, and the eight into sixteen, 

 all without intervening growth. The last-formed individuals have no 

 resemblance to the original parent form, but each has a macronucleus 



