96 



EVOLUTION 



which there must have been many a great 

 step among plants as well as among animals. 

 In the second place, the fact that plants 

 have made no such very great advance since 

 the Devonian period, whereas animals have 

 risen by stride after stride to higher and 

 higher levels of organization, is congruent 

 with the deep contrast between plants and 

 animals to which we have already referred. 

 It is not merely that plants in their struc- 

 tural relations remain about the level of 

 Coelentera among animals; it is that they 

 are on an entirely different line of evolution. 

 Plants and animals are incommensurable and 

 antithetic. 



If we take a series of sedentary animals, 

 such as zoophytes or alcyonarian corals, we 

 find, as in plants, a wealth of variety within 

 narrow range, an exhausting of the possi- 

 bilities of ramification and colony-making, a 

 great development of hard supporting parts, 

 and many nice adjustments to slight environ- 

 mental peculiarities. They and the plants 

 have a similar kind of beauty expressing the 

 dream-smiles of their sleep-like life. 



How different this is from what we see 

 among the free-living animals which made 

 one important step after another. Keeping 

 to backboneless animals for the moment, let 



