AGGREGATION AS A PROCESS 149 



typic, in which he was followed by Wheeler (1930). Apart from this 

 agreement, however, the viewpoint of the leading students of social 

 behavior in animals differs materially from that of the bio-ecologist, 

 and this is reflected to a large degree in both concepts and terminology. 



This divergence is exemplified by Deegener's classification of ani- 

 mal communities, in which he distinguishes "associations" as acci- 

 dental and serving no useful purpose to the individual members, and 

 "societies" as essential and rendering a useful return to the individuals, 

 or at least some of them (1917, 1918; cf. Alice, 1931, a: 15). These 

 are divided and subdivided to yield more than a hundred types, but, 

 as the system is primarily a static one and burdened with a sesquipe- 

 dalian terminology, it possesses little pertinence for the present treat- 

 ment (cf. Allee, loc. cit., page 14). It appears certain that aggrega- 

 tion will sometime be analyzed in considerable detail, especially with 

 reference to the groupings of plants and animals both on land and in 

 water, but this must follow much more extensive c^uantitative and 

 experimental studies in the field. 



Consequences of Aggregation. It is obvious that the coaction of 

 coming together in a family or other group will set up other coactions 

 as corollaries of this, and each may be of greater or less significance 

 in the life of the community. The community may react upon the 

 habitat, or the individuals may interact with one another, in such 

 manner as to produce either beneficial or harmful effects. Quite fre- 

 quently the two results may be combined in various degrees, though 

 one or the other usually rules. In general, the intensity of effect 

 depends chiefly upon the space relations of the individuals in the 

 group, that is, upon the degree of crowding, so called, but it is also 

 influenced by the qualities of the organisms concerned. In general, 

 helpful coactions are more characteristic of the family and colony, and 

 harmful ones of the more complex communities, but there are striking 

 exceptions in both instances. The property of motility naturally plays 

 a large part in crowding and its consequences, as does also the type 

 of habitat, whether water, soil, or air. 



In accordance with the above, it becomes necessary to distinguish 

 three types of coaction following upon aggregation, on the basis of 

 mutual effect. Two of these, cooperation and competition, are well 

 known by name, but still too little understood as to fact; the third 

 deals with processes indirectly harmful and may consequently be 

 termed disoperation. It is clear that all three coactions may operate 

 in any community and that they are in fact exhibited in some degree 

 by practically all, though each grouping derives its distinctive charac- 

 ter from the predominant process. 



