ECOLOGICAL SUCCESSION. QI 



C. General Considerations. 



We note that the distribution of animal species which occur 

 chiefly on a particular plant species or on closely related species 

 of a group, do not often occur everywhere that the plant or plants 

 occur, and if they do there is a marked difference in the number 

 of individuals. Such phenomena appear to be matters of common 

 observation among naturalists. While they are still subjects for 

 investigation, there is much evidence that the local distribution 

 of the phytophaga is not that of the food plant or plants but is 

 limited to a certain portion of the local range of the plant, by 

 differences in the physical conditions, or the growth form of the 

 plant or both. The food plants of phytophaga having a number 

 of food plants are usually those growing in associations. The 

 fauna of trees growing in different communities or under different 

 conditions are probably commonly different. The differences in 

 the mores of the communities outlined above are clearly corre- 

 lated with factors known to be of importance in the behavior and 

 physiology of animals. These are materials for abode, soil 

 moisture, light and the condition of the atmosphere. 



The more important features of the environment of an animal 

 are selected through its reactions, which are probably innate or 

 instinctive (Wheeler, '10, p. 159; Shelford, 'n 4 , pp. 556-582; 

 Hancock, ' 1 1 , p. 327 ; Herrick, '05, p. 201 ) . Different species usu- 

 ally select different habitats or different strata in the same habitat . 

 It is well known among naturalists and experimenters that dif- 

 ferent species usually have different mores (Brehm, '96, p. 73). 



Animals of the same species show behavior differences in different 

 habitats (Jennings, '06, Ch. XXL; Shelford, 'n 4 , p. 584; Alice, 

 '12). Bohn found, that the sea anemones living near the surface 

 of the sea where the wave and tide action are strongest, showed 

 more marked rhythms of behavior in relation to tide than chose 

 living lower down where the action of the tide and waves is 

 less marked (Bohn, '10, p. 156; Holmes, '11, p. 155). These 

 rhythms disappeared slowly when the animals were removed 

 from the tide to the aquarium. Many such cases are probably 

 to be found in the natural history literature. For example the 

 chipmunk differs in behavior under different conditions (Wood, 



