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THE AMERICAN NATURALIST [Vol. XLVIII 



enee upon the animal. In addition to its effect in the con- 

 trol of temperature, light and other physical factors, the 

 vegetation constitutes the basic food-supply for the ani- 

 mal community, and also provides shelter and materials 

 for abode (A: 601). Cases of direct association between 

 particular plants and particular animals are numerous, 

 but the majority of animals have no direct relation to 

 particular kinds of plants. Behavior characters are in 

 general of greater importance in the relation of the 

 animal to the plant environment, though such relations 

 are not confined to psychological characters. 



There are two sets of relations between the animal and 

 its animal environment. These are: (1) social, and (2) 

 antagonistic. Social relations {inter-psychology and 

 inter-physiology of Shelf ord, A: 608, b) include those 

 between individuals of the same species, and between 

 animals of the same or similar mores 2 (ecologically equiv- 

 alent animals), in so far as these relations are not 

 antagonistic. Breeding and family relations are the 

 principal activities which come under this head. Be- 

 havior characters are of greatest importance, as compared 

 with structural and other characters. The antagonistic 

 relations constitute the intermores-psychology and phys- 

 iology of Shelford (A: 608, c). They are the antagonistic 

 relations between animals not ecologically equivalent, and 

 they are also antagonistic relations within a species and 

 between ecologically similar forms. These relations are 

 probably not greatly concerned with reproduction, but 

 center about the feeding activities of the animal. The 

 existence of the individual animal, in its relation to other 

 organisms, is dependent upon three conditions: (1) it 

 must obtain suitable and sufficient food, (2) it must be 

 free from destructive competition of animals of similar 

 requirements, (3) it must be able to escape or to with- 

 stand attacks of other animals (or, sometimes, of para- 

 sitic fungi or bacteria). The various characters of the 



2 Mores (Latin for customs, habits) has been used by Shelford (1911a: 

 30) to supply the need for a term including all physiological and behavior 



