LIFE AS ADJUSTMENT 



^simpler and more homogeneous changes which 

 iffect their total environment. The relations 

 established within a plant answer only to the 

 >resence or absence of a certain quantity of 

 light and heat, and to the chemical and hy- 

 rrometric relations existing in the enveloping 

 itmosphere and subjacent soil. In a polyp, be- 

 jides general relations similar to these, certain 

 iore special relations are established in corre- 

 spondence with the external existence of me- 

 :hanical irritants ; as when its tentacles contract 

 in being touched. The increase of extension 

 icquired by the correspondences as we ascend 

 :he animal scale may be seen by contrasting 

 :he polyp, which can simply distinguish be- 

 tween soluble and insoluble matters, or between 

 opacity and translucence, in its environment, 

 ith the keen-scented bloodhound and the far- 

 jighted vulture. And the increase of complexity 

 lay be appreciated by comparing the motions 

 respectively gone through by the polyp on the 

 ►ne hand, and by the dog and vulture on the 

 ►ther, while securing and disposing of their 

 >rey. In the next chapter it will be shown that 

 the advance from lower to higher forms of life 

 :onsists in the orderly establishment of relations 

 dthin the organism, answering to external re- 

 lations of coexistence and sequence, that are 

 rontinually more special, more remote in space 

 ind in time, and more heterogeneous ; until at 



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