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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