DARWIN AND THE ORIGIN OF SPECIES 229 



However slight the advantage may be, if it is shared by half the 

 individuals produced, it will probably be present in at least fifty- 

 one of the survivors, and in a larger proportion of their offspring ; 

 but the chances are against the preservation of any one ' sport ' 

 in a numerous tribe. The vague use of an imperfectly under- 

 stood doctrine of chance has led Darwinian supporters, first, to 

 confuse the two cases above distinguished; and, secondly, to 

 imagine that a very slight balance in favour of some individual 

 sport must lead to its perpetuation. All that can be said, is 

 that in the above example the favoured sport would be preserved 

 once in fifty times. Let us consider what will be its influence 

 on the main stock when preserved. It will breed and have a 

 progeny of say 100 ; now this progeny will, on the whole, be 

 intermediate between the average individual and the sport. 

 The odds in favour of one of this generation of the new breed 

 will be, say 1 \ to 1, as compared with the average individual ; 

 the odds in their favour will therefore be less than that of their 

 parent ; but owing to their greater number, the chances are that 

 about 1^ of them would survive. Unless these breed together, 

 a most improbable event, their progeny would again approach 

 the average individual; there would be 150 of them, and their 

 superiority would be say in the ratio of 1J to 1 ; the probability 

 would now be that nearly two of them would survive, and have 

 200 children, with an eighth superiority. Rather more than 

 two of these would survive ; but the superiority would again 

 dwindle, 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 

 learnt. Suppose 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 possess over the 

 native ; concede that in the struggle for existence his chance of 

 a long life will be much superior to that of the native chiefs ; 

 yet from all these admissions there does not follow the conclu T 



