Darwin s Artificial and Natural Selection 109 



individuals of any species which are periodically born, but a 

 small number can survive. I have called this principle, by 

 which each slight variation, if useful, is preserved, by the 

 term Natural Selection, in order to mark its relation to man's 

 power of selection. But the expression often used by Mr. 

 Herbert Spencer of the Survival of the Fittest is more 

 accurate, and is sometimes equally convenient. We have 

 seen that man by selection can certainly produce great re- 

 sults, and can adapt organic beings to his own uses, through 

 the accumulation of slight but useful variations, given to 

 him by the hand of Nature. But Natural Selection, as we 

 shall hereafter see, is a power incessantly ready for action, 

 and is as immeasurably superior to man's feeble efforts, as 

 the works of Nature are to those of Art." 



Darwin gives the following explicit statement of the way 

 in which he intends the term "struggle for existence" to be 

 understood : " 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 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 mois- 

 ture. A plant which actually produces a thousand seeds of 

 which only one on 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 dis- 



