8 ANIMAL LIFE 



Amoeba is irritable ; it possesses irritability, which is sensa- 

 tion in its simplest degree. 



If food is abundant the Amceba soon increases in size. 

 The bulk of its body is bound to increase if new substance 



FIG. 4. Amoeba polypodia in six successive stages of division. The dark, white- 

 margined spot in the interior is the nucleus. After F. E. SCHULZE. 



is constantly assimilated and added to it. The Amceba 

 grows. But there seem to be some fixed limits to the 

 extent of this increase in size. No Amceba becomes large. 

 A remarkable phenomenon always occurs to prevent this. 



