AM(EBA. 



19 



ing the particles of food ingested by the amoeba. This pro- 

 teus-animalcule is neither provided with mouth nor anus. The 

 food can be taken in and expelled at any part of the body. 

 This process can easily be watched if particles of indigo are 

 placed in the water surrounding an amoeba : a speck of indigo 

 will be found to be drawn to the protozoon by the pseudo- 

 podium, and then it can be watched gradually sinking into the 

 protoplasm until it reaches the endosarc, where it remains 

 whilst the substance (if an organism) is digested, the waste part 

 being expelled through any part of the animal. The food con- 



S.tt-,- 



7v. 



.-« 



Pig. 2.— Ajkeba (greatly magnified). 



i. Large specimen, showing structure, ii. A smaller specimen in process of division, 

 iii. Later stage of ii. a and n, nucleus ; h and cv, contractile vacuoles ; Fv, food 

 vacuoles ; Fsu, pseudopodia. 



sists of organisms stiU smaller than the amoebse are themselves. 

 Amoeba reproduces by the primitive method of " fission " or 

 division. The nucleus of the amoeba divides into two (fig. 2, 

 ii. and iii., a), and one of these nuclei, surrounded by part of the 

 original protoplasm, breaks off and floats away ; thus one amoeba 

 becomes two. This division may go on until one amoeba has 

 given rise to hundreds. But by degrees each amoeba becomes 

 smaller and smaller, and they would eventually die out. To 

 counteract this, what is known as " rejuvenescence " takes place. 

 Eejuvenescence is the union or conjugation of two amoebae, 



