26 INHERITANCE, VARIATION AND SELECTION. 



the slightest doubt about the two trees being oak trees, and a 

 botanist will instantly tell us to which species they belong of the 

 two or three hundred into which oaks are divided. If we take other 

 acorns from these two trees, and from 1 them raise other oak trees, 

 they in their turn will have the same points of similarity and differ- 

 ence which have just been noted. 



HEREDITY AND VARIATION. 



This difference in identity exists in every species of plants and 

 animals, and illustrates both the laws of heredity and the phe- 

 nomena of variation, though it explains neither. The laws of 

 heredity declare that the offspring are and will be the same as 

 the parent, while the facts of variation teach us that accompanying 

 this likeness there is an unlikeness. From common observation 

 we are led to expect that- the children of negro parents will be 

 born with dark skins and curly hair; that the Chinese child will 

 have slant eyes and the peculiar traits of Mongolian people; and 

 that the child of white parents will have those peculiarities that 

 characterize the white race. Going further we can distinguish 

 different branches of the white race, and can tell the children of 

 German, Irish or Italian parents from each other. Even within 

 these branches we can often recognize brothers and sisters and 

 know them to be children of particular parents. 



That a son looks like his father or mother has become so familiar 

 to us that we are surprised when he does not, yet few persons who 

 have not given the matter special attention are fully aware of the 

 power of the laws of heredity and the persistency with which par- 

 ticular characters are transmitted from generation to generation. 

 Many examples have been given by writers on the subject of 

 heredity, but it is intended to give here only enough to illustrate 



