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- 
