The Web of Life 101 



§12. The Gist of Darwinism: (A) The Web of Life. 



The general idea of evolution is that the present is 

 the child of the past and the parent of the future. 

 But what are the characteristics of the particular 

 form of organic evolutionism that is familiarly called 

 "Darwinism"? This is the subject of frequent mis- 

 understanding. There are in "Darwinism" four great 

 ideas. First, there is the image of the Web of Life — 

 the correlation of organisms, the linkages binding one 

 living creature to another in a vital economy. Cats 

 are connected, Darwin told us, with the success of 

 next year's clover crop. Cats have also something to 

 do with the incidence of the plague in India; and 

 little fishes, by devouring mosquito larvae, play their 

 part in checking the dissemination of malaria. 

 Water-wagtails in Britain have something to do with 

 profitable sheep-farming, for they devour the fresh- 

 water snail that harbors the juvenile stages of the 

 fluke-worm, responsible for the disease of liver-rot 

 in sheep. Everyone knows what far-reaching harm 

 the European sparrow has done in the United States. 

 Earthworms have made most of the fertile soil of the 

 world, and the white-ants or termites on the outskirts 

 of the forests contribute to the making of the allu- 

 vium of distant valleys. Flowers and insects are fitted 

 to one another as glove to hand; in many cases the 

 flowers would probably disappear without their visi- 

 tors and the insects without their flowers. As John 

 Locke said, with his characteristic insight, nothing 

 stands by itself ; everything is a retainer to some other 

 part of nature. The circle of one creature's life cuts 



