ANIMAL COMMUNITIES 35 



Communities in Temperate America (The University 

 of Chicago Press, Chicago, 1913). He has tried to 

 obtain a picture of a small portion of the web of life, 

 a picture which would show the relations of animals 

 to one another, to plants and to physical environ- 

 ment, to see the struggle for life as it exists, to appre- 

 ciate the conditions of failure and success. He is no 

 sentimentalist. He expects to find nature " cruel 

 and heartless"; he admits that "to die to become 

 the food of another organism is the fate of the vast 

 majority of animals." The general nature of his 

 conclusions is shown by his title. The animals of 

 any given region form what he calls animal com- 

 munities, each community consisting of a number of 

 species that have selected a particular environ- 

 mental complex. The selection of the habitat comes 

 about partly by a method of trial and error, which 

 is instinctive rather than conscious, and partly by 

 the adjustment of behaviour to the conditions, such 

 adjustment again being probably unconscious. The 

 different groups form stream, pond, lake, prairie, 

 thicket and forest communities, and their rela- 

 tions to one another and to the environment, to 

 relatively stable conditions and to changing condi- 

 tions, have been carefully analysed and show the most 

 finely balanced system of interdependence and uncon- 

 scious co-operation. Natural suitability to the organic 

 and inorganic environment and capacity to adapt be- 

 haviour to circumstances are the dominant factors in 

 successful struggle, and there is no trace of the remotest 

 resemblance with human warfare. This is the struggle 

 for existence as Darwin thought of it. In Darwin's 

 own words, when one species is more successful than 



