434 THE CAUSES OF THE XI 
of particular places. In the next place there is 
what is technically called STATION, which means 
—given the climate, the particular kind of place 
in which an animal or a plant lives or grows; for 
example, the station of a fish is in the water, of a 
fresh-water fish in fresh water; the station of a 
marine fish is in the sea, and a marine animal 
may have a station higher or deeper. So again 
with land animals : the differences in their stations 
are those of different soils and neighbourhoods; 
some being best adapted to a calcareous, and 
others to an arenaceous soil. The third condition 
of existence is FoopD, by which I mean food in 
the broadest sense, the supply of the materials 
necessary to the existence of an organic being ; in 
the case of a plant the inorganic matters, such as 
carbonic acid, water, ammonia, and the earthy 
salts or salines ; in the case of the animal the in- 
organic and organic matters, which we have seen 
they require ; then these are all, at least the first 
two, what we may call the imorganic or physical 
conditions of existence. Food takes a mid-place, © 
and then come the organic conditions; by which 
I mean the conditions which depend upon the 
state of the rest of the organic creation, upon the 
number and kind of living beings, with which an 
animal is surrounded. You may class these under 
two heads: there are organic beings, which operate 
as opponents, and there are organic beings which 
operate as helpers to any given organic creature, 
