140 



ANIMALS 



demonstrates his superiority. The life of the amoeba is brief 

 in time as well as circumscribed in space; the range of its experi- 

 ences are as limited as its sensibilities are vague and the memory 

 of them instantly vanishes. The wolf, however, lives on for 



days, months and years. His 

 highly specialized nerve cells not 

 only feel infinitely more acutely 

 but they are able to retain impres- 

 sions, and through his compara- 

 tively long life these accumulated 

 experiences are made to serve to 

 his advantage. The intelligence 

 of the wolf goes far to make him 

 independent of his environment 

 and he thereby demonstrates his 

 superiority. The highest animals 

 are those most completely inde- 

 pendent of the conditions under 

 which they live. 



333- Segmentation. — Compar- 

 ing the larger and smaller animals 

 again from another point of view: 

 The greater size of the body may 

 be due to larger organs, or it may 

 also result from a repetition of 

 similar organs, as in plants. The 

 former condition is well exempli- 

 fied by the phylum MoUusca, in 

 which the repetition of similar 

 organs (in this sense) does not occur, and yet one class of 

 this phylum (Cephalopods) has attained a high degree of 

 development, and counts, in some of its species, animals of the 

 greatest size. 



334. When repetition of organs occurs it may afifect some 



Fig. 67. — The anterior end of 

 an annelid, Nereis. The body 

 consists of upward of 130 similar 

 segments or metameres. Hence 

 the animal is said to be homon- 

 omously segmented. 



