Unicellular^ Microscopic Animals 345 



cytoplasm, and the food vacuole disappears. Within the cytoplasm the 

 absorbed foods are assimilated (made into living protoplasm) , Complex 

 molecules of protoplasm are oxidized to release the energy needed for 

 movement, locomotion, the production of heat, and other physiologic 

 activities. 





FOOD 

 VACUOLE 



COMTRACTIL.E 

 VACUOUE 



NUCU.EUS 



ENDOPl_ASM 



^ PSEUDO PODIUM 



ECXOPUASM 



Fig. 157. — Amoeba proteus of the class Sarcodina (magnified and somewhat dia- 

 grammatic). (From Potter: Textbook of Zoology, The C. V. Mosby Co.) 



Fig. 158. — Amoeba proteus showing various shapes revealed by a photomicrograph. 

 (From White: General Biology, The C. V. Mosby Co.) 



Motion and Loconiotion. — Amoeba moves from place to place (loco- 

 motes) and captures foods by the fingerlike pseudopodia, commonly 

 referred to as "pseudopods." They may form on any surface by pushing 

 out a blunt projection of clear ectoplasm into which flows the granular 

 endoplasm. Two theories regarding the formation of pseudopodia are 

 ( 1 ) the surface tension theory, based on changes in the tension of the sur- 

 face of the amoeba, and (2) the viscosity theory, based on the tendency 

 to resist changes in the shape or arrangement of parts. 



