PRINCIPLE OF NATURAL SELECTION. 22$ 



acquainted with these. He had recognized, as 

 did others before him, specific variations as 

 material out of which new species must be 

 made, and had gone to work systematically to 

 study variations, especially in domestic pigeons, 

 the most favorable group of animals that could 

 have been selected ; and had recognized selec- 

 tion as the key to man's success in the produc- 

 tion of races. His study hitherto had helped 

 him to a wider knowledge and clearer notion 

 of adaptations, the effects that had to be 

 explained; and a better understanding of the 

 nature and range of variations, the materials 

 upon which the cause must have acted to pro- 

 duce the effects. And in the case of domestic 

 productions he was in full possession of the 

 cause, the materials on which the cause acted, 

 and the results, in selection, variations, and 

 races. As he himself said, he had been fully pre- 

 pared by his long study of the habits of animals 

 to appreciate the struggle for existence which 

 everywhere goes on. " It at once struck me," he 

 said, "that under these circumstances favorable 

 variations would be preserved and unfavorable 

 ones destroyed. The result of this would be 

 the formation of new species. Here, then, I had 

 at last got a theory by which to work." 1 



1 Life and Letters, Vol. I. p. 68. 



