26 



MULTICELLULAR ORGANISMS 



chemical agents produce changes in the rate of locomo- 

 tion or alter its direction ; hence the amoeba feels. There 

 is also a definite spot where the water accumulates until 

 it forms a droplet about the size of the nucleus, where- 

 upon it is emptied to the outside. It is generally be- 

 lieved that waste products enter this contractile vacuole, 

 which thus acts as a simple kidney or excreting organ. 



Fio. 5. — ParamoBcium or slipper animalcule, cv, contractile 

 vacuole or Himple kidney; m, mouth and gullet; n, nucleus. B, two 

 individuals conjugating, a type of fertilization. C, individual dividing 

 asexually. 



When the body reaches a certain size it divides into two 

 equal halves, each of which thenceforth becomes an in- 

 dependent organism — a simple type of multiplication 

 of individuals. 



Paramcfxium. — In the paramoecium or slipper ani- 

 malcule (Fig. 5), living in the same situations as the 



