Heredity and Natural Selection. 279 



are that about one and a half of them would survive. 

 Unless these breed together, a most improbable event, 

 their progeny would again approach the average indi- 

 vidual; there would be 150 of them, and their superior- 

 ity would be, say, in the ratio of one and a quarter to 

 one; the probability would now be that nearly two 

 of them would survive and have 200 children with an 

 eiglith superiority. Rather more than two of these 

 would survive, but the superiority would agiiin dwin- 

 dle, until after a few generations it would no longer be 

 observed, and would count for no more in the struggle 

 for life than any of the hundred trifling advantages 

 which occur in the ordinary organs. An illustration 

 will bring this conception home. Suppose a white man 

 to have been wrecked on an island inhabited by negroes, 

 and to have established himself in friendly relations with 

 a powerful tribe, whose customs he has learned. Sup- 

 pose him to possess the physical strength, energy and 

 ability of a dominant white race, and let the food and 

 climate of the island suit his constitution; grant him 

 every advantage which we can conceive a white to pos- 

 sess over the native; concede that in the struggle for 

 existence his chance of a long life will be much supe- 

 rior to that of the native chiefs; yet from all these ad- 

 missions there does not follow the conclusion that, after 

 a limited or unlimited number of generations, the in- 

 habitants of the island will be white. Our shipwrecked 

 hero would probably become king; he would kill a great 

 many blacks in the struggle for existence; he would 

 have a great many wives and children. In the first gen- 

 eration there will be some dozens of "intelliirent youns: 

 mulattoes, much superior in average intelligence to the 

 negroes. We might expect the throne for some genera- 

 tions to be occupied by a more or less yellow king; but 



