56 STRUGGLE FOR EXISTENCE. 



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 de- 

 stroyed 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 LARGB 



SENSE. 



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

 metaphorical 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 properly 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 metaphorically 

 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 Exist- 

 ence. 



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 season or occasional year; 

 otherwise, on the principle of geometrical increase, its num- 

 bers would quickly become so inordinately great that nt 



