110 THE WORLD OF LIFE 



spring are like their parents. This is so common, so well 

 known to everybody, so absolutely universal in ordinary ex- 

 perience, 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 pro- 

 duce 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 pro- 

 ducing 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 in- 

 herited, because it so often happens that men of genius have 

 quite undistingaiished parents, and that the children of men 

 of great ability do not as a rule equal their fathers. But al- 

 though such cases are frequent and attract attention because 

 such apparent non-inheritance is unexpected and seems un- 

 reasonable, 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 gen- 

 erally 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 brieflv 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 inherit- 



