CHAPTER X 

 THE DOCTRINE OF EVOLUTION 



To the open ear it sings 



Sweet the genesis of things, 



Of tendency through countless ages, 



Of star-dust and star pilgrimages, 



Of rounded worlds, of space and time, 



Of the old flood's subsiding slime, 



Of chemic matter, force and form, 



Of poles and powers, cold, wet, and warm. 



EMERSOX, Wood Notes. 



Definition of Evolution. The word " evolution," in its most 

 general sense, signifies a process of unfolding or develop- 

 ment, and it is in this sense that we speak of the evolution 

 of a plan or the evolution of history. In science, generally, 

 the word is used to express the process of development from 

 simplicity to complexity ; that is, in the words of the Century 

 Dictionary, " to a nicer and more elaborate means for reach- 

 ing definite ends, the process being regarded as of the nature 

 of a growth." In this sense we speak of the evolution of our 

 solar system from a mass of heated gaseous material (see 

 p. 293). In biology (the science which has to do with living 

 things, both plants and animals) the word is used not only 

 to signify the development of an individual organism from 

 the egg to maturity, but it serves to characterize a particular 

 view as to the derivation of all organisms by natural descent, 

 with modification of earlier and simpler forms of life. Biolo- 

 gists are generally agreed that all the many species of animals 

 and plants of to-day have come to their present form through 

 evolution, though the steps by which this evolution has been 

 accomplished are not thoroughly understood. A classification 



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