Chap. II.] 



AMCEBA. 



Looked at more closely, we see in it evidences of dif- 

 ferentiation of structure ; the mass, small as it is, 

 is not homogeneous ; the outer portion is denser and 



n 



^&\V 







y ?.*?> 



Fig. 1. Amoeba. 

 w, Xuclcus ; cv, contractile vacuoles. 



clearer (Fig. 1) than the inner, which is more fluid 

 and granular. Although these two portions are not 

 sharply marked off from one another, it is convenient 

 to have definite names by which to distinguish them, 

 and we will speak therefore of an ectosarc, and an 

 eiidosarc. Within the endosarc we see a disk- 

 shaped or rounded body which retains its form, while 



