8 ANIMAL AGGREGATIONS 



doubts the applicability of Deegener's basic principle of benefit or 

 no benefit, but commends Alverdes' position as being essentially 

 sound. 



The ecological use of these and related terms must needs be con- 

 sidered. Modern ecological work has shown that each different kind 

 of a habitat contains a more or less characteristic set of animals 

 which are not mere accidental assemblages but are interrelated com- 

 munities. When these are geographic in extent, they are usually 

 spoken of as a "formation," within which may be recognized smaller 

 units or "associations," which are composed of groups of habitat 

 strata that are uniform over a considerable area but smaller than a 

 formation. These associations are frequently composed, at least in 

 part, of developmental stages, such that an orderly succession of 

 communities can be recognized. Such a series, forming a unit of 

 succession from initial to climax stages of an association, is some- 

 times called a "sere"; and the different developmental units of the 

 whole association are called "associes." Thus, we have the animal 

 communities or associes of the open sand, the foredune, the pines, 

 the oaks, and fmally the beech and maple forest, forming one de- 

 velopmental sere arranged in the order given, within the beach and 

 maple association near Chicago (Smith, 1928; Shackleford, 1929). 



In ecology the term "animal society," according to the most re- 

 cent usage (Smith, 1928), has been divided into two parts, one of 

 which is called a "pre-society."^ This is a community of organisms 

 living among the plants of an association and subordinate to the 

 plant dominants. The "plant association" is named for one or more 

 of the dominant plants, while one or more of the predominant ani- 

 mals give the name for the "super-society." The super-society, like 

 its accompanying plant association, generally covers an extensive 

 area with an essentially uniform taxonomic composition. Within such 

 a super-society one finds animal societies which are communities of 

 lesser magnitude and which may be seasonal, or stratal, or confined 

 to a given locality. When these societies, or recognizable subdivi- 

 sions of them, are composed of animals closely bound together by 

 biotic relationships such as have been described in general terms as 



' "Super-society" would appear to fit the meaning more exactly. 



