1 74 Note. 



why did this favourable modification not take place in any 

 of the intermediate stages between the two which were, 

 ex hypothesi, an improvement on amphibia, or they would 

 never have been evolved ? 



Also there is another difficulty, even more formidable, 

 that has been very well put in the "North British Review," 

 vol. xlvi. p. 288, et seq. It is that no race could be formed 

 in a state of nature by a sport, however advantageous, 

 unless it be supposed, in addition, quite gratuitously to 

 possess a quite unheard of and almost impossible degree 

 of prepotence ; because, otherwise, its advantages would 

 be more than counterbalanced by the numerical superiority 

 of the original form. "A million creatures are born ; 

 ten thousand survive to produce offspring. One of the 

 million has twice as good a chance as any other of sur- 

 viving ; but the chances are fifty to one against the gifted 

 individual being one of the hundred survivors. No doubt 

 the chances are twice as great against any one other 

 individual ; but this does not prevent their being enor- 

 mously in favour of some average individual," and the 

 favourable variation would soon be reabsorbed into the 

 ordinary form. The Reviewer goes on to say : " An illus- 

 tration 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 eve^ advantage which we can conceive a white to 



