AMEBA 51 



Ameba takes in food, gives off waste material, and carries on 

 respiration through its surface, the activities of the cell must 

 decrease with increase in size until further growth is impossible. 

 The solution of the problem is the division of the animal into 

 two, whereby the original ratio between surface and volume is 

 restored. Reproduction by binary division, therefore, takes 



fi ^? */ jto-iix X-^ V .f^./iy*- 



FIG. 16. Ameba poly podia dividing by binary fission. (From Parker and 

 Haswell after F. E. Schulze.) 



place when growth is no longer possible. It is supposed that this 

 division is inaugurated through some unknown change in the 

 relations between the nucleus and cytoplasm. There are at 

 least two kinds of reproduction in Ameba proteus,but neither has 

 ever been satisfactorily worked out in detail. They are (i; binary 

 division and (2) sporulation. 



