The Making of Species 



some perhaps becoming less carnivorous. The 

 more diversified in habits and structure the 

 descendants of our carnivorous animal become, 

 the more places they will be enabled to occupy. 

 What applies to one animal will apply throughout 

 all time to all animals that is, if they vary for 

 otherwise natural selection can effect nothing." 

 Darwin was, therefore, of opinion that natural 

 selection is able to bring about polytypic evolu- 

 tion. Darwin tacitly assumes, in the illustration 

 he gives, that the various races of the carnivorous 

 animal are in some way prevented from inter- 

 crossing ; for if they interbreed indiscriminately, 

 these races will tend to be obliterated. 



" That perfectly free intercrossing," writes 

 Professor Lloyd Morgan (on p. 98 of Animal 

 Life and Intelligence), " between any or all of the 

 individuals of a given group of animals is, so 

 long as the characters of the parents are blended 

 in the offspring, fatal to divergence of character, 

 is undeniable. Through the elimination of less 

 favourable variations, the swiftness, strength, 

 and cunning of a race may be gradually im- 

 proved. But no form of elimination can possibly 

 differentiate the group into swift, strong, and 

 cunning varieties, distinct from each other, so 

 long as all three varieties freely interbreed, and 

 the characters of the parents blend with the 

 offspring. Elimination may and does give rise 

 to progress in any given group, as a group ; it 



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