20 FOOT-NOTES TO EVOLUTION. 
properly it should be said to be dependent upon the 
moisture. A plant which annually produces a thousand 
seeds, of which only one on an average comes to matur- 
ity, 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 it 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 dissemi- 
nated by birds, its existence depends upon them; and it 
may metaphorically be said to struggle with other fruit- 
bearing plants in tempting 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.’ ” 
Darwin says that there is nothing which people are 
more willing to concede than the struggle for existence, 
and yet nothing can be more inadequate than the ordi- 
nary conception of it. He further says: 
“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 occa- 
sional year; otherwise, on the principle of geometric 
increase, the numbers would quickly become so inordi- 
nately great that no country could support the product.” 
It is one of the axioms of mathematics that any geo- 
metrical progression will in time outrun any arithmetical 
one. Multiplication outruns addition. 
“Hence . . . there must in every case be a struggle 
for existence, either one individual with another of the 
