EVOLUTION AS A NATURAL PROCl.SS L;:, 



though this has been done for nioro than one hundml 

 successive generations the IcMigth of the tail lia,s not 

 been altered. Quite unconscious of the scientific prol)- 

 lem, many human races have performed precisely 

 similar experiments through centuries of time. In 

 some classes of Chinese, the feet of young girls have been 

 bound in such a way as to produce a small, malformed 

 foot, but this has not resulted in any hereditary dimi- 

 nution in the size of the feet of Chinese fomales. 

 Many other similar mutilations have been practised, 

 as for example, the flattening of the sknll of some 

 North American Indians, but the deformity must be 

 produced again with each recurring generation. One 

 after another, the cases that were supposed to give 

 positive evidence have been reinvestigated, with the 

 result that has been stated above. It would seem, 

 therefore, that heredity and congenital modification 

 must play by far the greater part in the evolution 

 of species. 



The doctrine of natural selection took form in tlie 

 mind of Darwin mainly on account of threc^ potent 

 influences; these were, first, the geological doctrine 

 of uniformitarianism proposed by Lyell, second, his 

 own observations of wild life in many lands and his 

 analysis of the breeder's results with domesticated 

 animals, and third, the writings of Mnlthus d(>aling with 

 overpopulation. As Darwin had read the works 

 of Buffon, Lamarck, and Erasmus Danvin. his grand- 

 father, who had written a famous treatise imder the 

 title of ^^Zoonomia," he was familiar with the evidences 



