46 STRUGGLE FOR EXISTENCE. [CHAP. III. 



one has treated this subject with more spirit and ability than W. 

 Herbert, Dean of Manchester, evidently the result of his great 

 horticultural knowledge. Nothing is easier than to admit in words 

 the truth of the universal struggle for life, or more difficult at 

 least I have found it so than constantly to bear this conclusion 

 in mind. Yet unless it be thoroughly engrained in the mind, the 

 whole economy of nature, with every fact on distribution, rarity, 

 abundance, extinction, and variation, will be dimly seen or quite 

 misunderstood. We behold the face of nature bright with glad- 

 ness, we often see superabundance of food ; we do not see or we 

 forget, that the birds which are idly singing round us mostly live 

 on insects or seeds, and are thus constantly destroying life ; or we 

 forget how largely these songsters, or their eggs, or their nestlings, 

 are destroyed by birds and beasts of prey ; we do not always bear 

 in mind, that, though food may be now superabundant, it is not 

 so at all seasons of each recurring year. 



The Term, Struggle for Existence, used in a large sense. 



I should premise that I use this term in a large and meta- 

 phorical sense including dependence of one being on another, 

 and including (which is more important) not only the life of the 

 individual, but success in leaving progeny. Two canine animals, 

 in a time of dearth, may be truly said to struggle with each other 

 which shall get food and live. But a plant on the edge of a desert 

 is said to struggle for life against the drought, though more pro- 

 perly it should be said to be dependent on the moisture. A plant 

 which annually produces a thousand seeds, of which only one of 

 an average comes to maturity, may be more truly said to struggle 

 with the plants of the same and other kinds which already clothe 

 the ground. The mistletoe is dependent on the apple and a few 

 other trees, but can only in a far-fetched sense be said to struggle 

 with these trees, for, if too many of these parasites grow on the 

 same tree, it languishes and dies. But several seedling mistletoes, 

 growing close together on the same branch, may more truly be 

 said to struggle with each other. As the mistletoe is disseminated 

 by birds, its existence depends on them , and it may metaphori- 

 cally be said to struggle with other fruit-bearing plants, in tempt- 

 ing the birds to devour and thus disseminate its seeds. In these 

 several senses, which pass into each other, I use for convenience' 

 sake the general term of Struggle for Existence. 



Geometrical Ratio of Increase. 



A struggle for existence inevitably follows from the high rate at 

 which all organic beings tend to increase. Every being, which 

 during its natural lifetime produces several eggs or seeds, must 

 suffer destruction during some period of its life, and during some 



