78 
STRUGGLE FOR EXISTENCE. 
Chap. III. 
that it can perfectly well withstand a little more heat 
or cold, dampness or dryness, for elsewhere it ranges 
into slightly hotter or colder, damper or drier districts. 
In this case we can clearly see that if we wished in 
imagination to give the plant the power of increasing 
in number, we should have to give it some advantage 
over its competitors, or over the animals which preyed 
on it. On the confines of its geographical range, a change 
of constitution with respect to climate would clearly 
be an advantage to our plant; but we have reason 
to believe that only a few plants or animals range so 
far, that they are destroyed by the rigour of the climate 
alone. Not until we reach the extreme confines of life, 
in the Arctic regions or on the borders of an utter desert, 
will competition cease. The land may be extremely 
cold or dry, yet there will be competition between some 
few species, or between the individuals of the same 
species, for the warmest or dampest spots. 
Hence, also, we can see that when a plant or animal 
is placed in a new country amongst new competitors, 
though the climate may be exactly the same as in its 
former home, yet the conditions of its life will generally 
be changed in an essential manner. If we wished to in¬ 
crease its average numbers in its new home, we should 
have to modify it in a different way to what we should 
have done in its native country ; for we should have to 
give it some advantage over a different set of com¬ 
petitors or enemies. 
It is good thus to try in our imagination to give any 
form some advantage over another. Probably in no 
single instance should we know what to do, so as to 
succeed. It will convince us of our ignorance on the 
mutual relations of all organic beings; a conviction as 
necessary, as it seems to be difficult to acquire. All 
that we can do, is to keep steadily in mind that each 
