PROTOZOA 



147 



microscope it is seen to consist of an irregular mass of jelly-like 

 protoplasm without even a cell wall, hence its body (the one cell) 

 constantly changes shape, with a sort of flowing motion. A nucleus 

 may be seen as well as tiny particles of food which are scattered 

 through the protoplasm, and also a bubble-like cavity (vacuole) 

 which expands slowly and then contracts suddenly, forcing out its 



FIG. 44. Amoeba proteus in active moving condition, c.v., contractile vacuole; 

 f.v., food vacuole; , nucleus; />, remains of former pseudopodia. w.v., water 

 vacuoles. The arrows indicate the direction of protoplasmic flow. (Sedgewick 

 and Wilson.) From Calkins. 



contents. Simple as is its structure, one learns to look with re- 

 spect and interest upon an animal which with so little material, 

 can yet perform all the functions necessary to any organism, 

 however complex. 



The amoeba obtains food by extending lobes of its protoplasm 

 and actually flowing around each particle. Digestion and as- 



