Some make the creature more desirable for human purposes and 

 some less desirable. Man, by selecting and breeding from individ- 

 uals having favorable variations, has produced widely diverse breeds, 

 adapted to his various purposes. In nature, we find individual 

 variations of the same kind that we find under domestication indefi- 

 nite or approximately chance variations. We also find in nature 

 a selecting agency; the struggle for existence. Of the vast num- 

 ber of offspring born each year of animals and plants, a greal 

 percentage perish because not well enough adapted to the surround- 

 ings in which they are born. Those individuals having variations 

 favorably adapting them to the conditions of life will more often 

 survive than those not having such variations. The surviving individ- 

 uals will, individual variations being hereditary, breed their kind; 

 from their offspring, selection will again be made; and this process 

 continuing from generation to generation, through long periods of 

 time, will give rise to breeds, often quite diverse and each well 

 adapted to live under the conditions of life in which it has been pro- 

 duced. It is admitted that varieties have been thus produced and 

 Darwin concludes from his argument that this also was the manner 

 of the origin of species. 



Similarities in organic structure and vital functions, in animals of 

 distinct species, suggested to Darwin the possibility of a common 

 origin. This was a natural hypothesis. It perhaps would be among 

 the first theories that would occur to a thinker, seeking an explana- 

 tion of such similarities. From experience with phenomena, it has 

 become natural to expect relationship where we find similarity. The 

 theory then which occurred to Darwin was one which, if suggested 

 to any other thinker having knowledge of the facts with which Darwin 

 was acquainted, would have seemed quite possible to him. 



A common origin was the natural inference from the phenomena 

 of marked similarities, similarity being so often to our knowledge the 

 result of relationship; but this inference raised the question, by what 

 means came the diversity to be. For, until it was shown how the 

 diversity came from the common origin, the theory of a common 

 origin would not possess great certainty ; but if it could be shown that 

 there were forces operating which would produce the diversity, then 

 the theory would gain greatly in strength. 



Darwin turned to nature in quest of the forces which he believed 

 must have worked and still were working to produce species. When 

 he consulted his experience he found under human control a process 

 by which diverse breeds were produced from a common stock of 

 animals. To understand fully this process and its possibilities, 

 Darwin experimented for many years. He then turned to nature 



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