102 THE WORLD OF LIFE 



" law " — of the organic world is, that like produces like — 

 that offspring are like their parents. This is so common, so 

 well known to everybody, so absolutely universal in ordinary 

 experience, that we are only surprised when there seems to 

 be any exception to it. In its widest sense as applied to 

 species there are no exceptions. Not only does the acorn 

 always produce an oak, the cat a kitten, which grows into a 

 cat, the sheep a lamb, and so throughout all nature, but 

 each different well-marked race also produces its like. We 

 recognise Chinese and Negroes as being men of the same 

 species as ourselves, but of different varieties or races, yet 

 these varieties always produce their like, and no case has 

 ever occurred of either race producing offspring in every 

 respect like one of the other races, any more than there are 

 cases of cart-horses producing racers or spaniels producing 

 greyhounds. 



Some people still think that mental qualities are not 

 inherited, because it so often happens that men of genius 

 have quite undistinguished parents, and that the children of 

 men of great ability do not as a rule equal their fathers. 

 But although such cases are frequent and attract attention 

 because such apparent non-inheritance is unexpected and 

 seems unreasonable, yet when large numbers of families are 

 carefully examined there is found to be the same amount of 

 mental as of physical inheritance. This was proved by 

 Sir Francis Galton in his work on Hereditary Genius, in 

 which, by tracing the families of large numbers of public 

 men of high position and some kind of exceptional talent or 

 genius which was generally recognised, it was found that in 

 their ancestral line there was always found some amount of 

 distinction, though not always of the same kind or degree ; 

 and that if they left descendants for two or three generations, 

 they, too, usually comprised some individuals of more than 

 average ability. 



To avoid any misconception on this point, it may be as 

 well here to state briefly the numerical law of inheritance, 

 which Galton arrived at by careful experiments in the 

 breeding of plants and animals, and which is now generally 

 accepted as affording a very close representation of the 

 facts of inheritance under normal conditions. It is that 



