Abstract
The term animal aggregations is used in a loose sense to cover those collections of animals in which the individuals are more or less closely associated without necessarily being in physical contact with each other. The extensive literature dealing with such groups or clusters is summarized, with particular reference to the method of formation of the aggregations, the general factors conditioning their formation, the harmful and beneficial results of crowding, the integration of such groups, and their social significance. In general the discussion avoids consideration of highly social animals. The paper is a contribution toward the organization of general sociology, and gives the general background of literature for specific researches by the author which are being published under the same general heading. A selected bibliography of 210 titles is appended.