ORGANIC EVOLUTION 71 



upon theory. It is known to have taken place ; 

 and the process by which the different varieties o\ 

 domestic animals and plants have been evolved — 

 domestic selection — is not different in principle 

 from the process of natural selection, the chief 

 operation by which life in general, both plant and 

 animal, is assumed to have been evolved. 



10. There are other reasons for a belief in 

 organic evolution, but the last one I shall mention 

 is the fact that the theory of organic evolution 

 harmonises with the known tendencies of the 

 universe as a whole. The organic kingdoms oi 

 the earth — animals and plants — are as truly parts 

 of the terrestrial globe as the inorganic kingdom 

 is; and as such they share in, and are actuated 

 by, the same great tendency or instinct as that 

 which actuates the whole. Nine-tenths of the 

 substance of all animals and plants is oxygen, 

 hydrogen, carbon, and nitrogen — the very elements 

 which make up the entire ocean and air, and 

 enter largely into the composition of the contin- 

 ents. The human body, which has essentially 

 the same chemical composition as the bodies of 

 animals in general, is made up of four solids, five 

 gases, and seven metals — in all, sixteen elements 

 of the something like seventy which constitute 

 the entire planet. * In the past, man appeared to 

 be a creature foreign to the earth, and placed 

 upon it as a transitory inhabitant by some incom- 

 prehensible power. The more perfect insight of 

 the present day sees man as a being whose 

 development has taken place in accordance with 



