THE STRUGGLE FOR EXISTENCE 73 



of natural selection was that he had so little of 

 the naturalist's mood and experience. 



DiEFERENT FORMS OP THE STRUGGLE FOR 



Existence. — Some of Darwin's successors have 

 taken pains to distinguish a great many different 

 forms of the struggle for existence, and this 

 kind of analysis is useful in keeping us aware of 

 the complexities of the process. Darwin himself 

 does not seem to have cared much for this logical 

 mapping out and defining ; it was enough for 

 him to insist that the phrase was used " in a 

 large and metaphorical sense," and to give full 

 illustrations of its various modes. For our present 

 purpose it is enough to follow his example. 



(a) Struggle between Fellows. — When the locusts 

 of a huge swarm have eaten up every green thing 

 they sometimes turn on one another. This canni- 

 balism among fellows of the same species — illus- 

 trated, for instance, among many fishes — is the 

 most intense form of the struggle for existence. 

 An eerie struggle occurs between sister embryos 

 in the egg-capsules of the buckie and the dog- 

 whelk on the sea-shore. This sort of thing has 

 its close analogue in what goes on between thick- 

 sown seedlings of the same kind, which compete 

 with one another for room and food and light. 

 The struggle does not need to be direct to be 

 real — the essential point is that the competitors 

 seek after the same desiderata of which there is 

 a limited supply. Whether an adult frog eats 

 a tadpole of its own kind, or a female spider 

 her suitor, or coral polyps compete for the same 

 niche, or rabbits for the same scanty food, the 

 formula is the same in all cases, and, apart from 

 chance, the result will be the same — the survival 



