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 FOOD, 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 inorganic 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* 



