PREFACE 



The attempt to summarize knowledge concerning the relations 

 within and between different sorts of animal societies is not new. 

 Espinas in 1878 undertook such an effort, and shows in his introduc- 

 tion that Aristotle, Spinoza, Leibnitz, Montesquieu, Kant, Hegel, 

 A. Comte, Herbert Spencer, and others had preceded him in the 

 consideration of certain aspects of this problem. Since the time of 

 Espinas, knowledge concerning the social insects and the develop- 

 ment of insect societies has greatly increased. Wheeler, Forel, 

 Buttel-Reepen, and many others have contributed both personal ob- 

 servations and generahzing summaries of value ; and I have no desire 

 to enter into a field so ably covered. There does remain, however, a 

 field of social, or perhaps subsocial, life almost entirely unJ;ouched by 

 these students. They have been concerned with the fascinating prob- 

 lems and intricate relationships presented by fairly well-developed 

 societies. Here, I propose to investigate the relationships existing 

 among the more loosely integrated collections of animals, which may 

 rightly be designated as "animal aggregations," with regard to their 

 ecological and behavioristic physiology, as well as with regard to 

 their strictly social implications. 



This book is built about a phenomenon or a series of phenomena, 

 rather than about a philosophy. In the present form it may even be 

 designated as notes on an unsolved problem; but since a presenta- 

 tion of a problem is necessary for its ultimate solution, and since an 

 inquiry into the universahty of a given problem is imperative before 

 undertaking laborious experimentation directed toward finding a 

 solution, no apology is offered for summarizing our growing knowl- 

 edge on the subject of animal aggregations at the present stage of 

 inquiry into the problems involved. 



My own experimental work within the field covered by the pres- 

 ent book began in 191 1 and has continued intermittently to date. 

 The investigation of animal aggregations has been at the center of 



