THE STRUGGLE FOR EXISTENCE. 163 
that the number of adult individuals is limited by other 
circumstances, especially by the relations in which the 
organism stands to its organic and inorganic surroundings. 
Every organism, from the commencement of its existence, 
struggles with a number of hostile influences: it struggles 
against animals which feed on it, and to which it is thenatural 
food, against animals of prey and parasites; it struggles 
against inorganic influences of the most varied kinds, against 
temperature, weather, and other circumstances ; but it also 
struggles (and this is much the most important !), above all, 
against organisms most like and akin to itself. Every 
individual, of every animal and vegetable species, is engaged 
in the fiercest competition with every other individual of 
the same species which lives in the same place with it. In 
the economy of nature the means of subsistence are 
nowhere scattered in abundance, but are very limited, 
and far from sufficient for the number of organisms which 
might develop from the germs produced. Therefore the 
young individuals of most species of animals and vegetables 
must have hard work in obtaining the means of subsist- 
ence ; this necessarily causes a competition among them in 
order to obtain the indispensable supplies of life. 
This great competition for the necessaries of life goes on 
everywhere and at all times, among human beings and 
animals as well as among plants; in the case of the latter 
this circumstance, at first sight, is not so clearly apparent. 
If we examine a field which is richly sown with wheat, 
we can see that of the numerous young plants (perhaps 
some thousands) which shoot up on a limited space, only a 
very small proportion preserve themselves in life. A com- 
petition takes place for the space of ground which each plant 
