4 ANIMAL AGGREGATIONS 



ber of investigators are convinced that without a knowledge of gen- 

 eral sociology we are likely to regard the social traits exhibited by 

 man or by the ants as being peculiarly human or peculiarly formi- 

 cine, when many of them are merely human or ant variations of 

 social traits common to animals in general. Again, it is difficult to 

 evaluate properly the origin and function of many of these general 

 social traits without a proper understanding of their physiological 

 antecedents among animals not usually regarded as having reached 

 the social level. It is quite easy to consider certain bits of behavior 

 as definitely social in origin and inherent in the social type of organi- 

 zation which may be merely specialized developments of general be- 

 havior common to most animals when crowded. 



One fallacy may be suggested at the beginning. All too frequently 

 one gains the impression that sex forms the main, if not the only, 

 physiological connecting link between the infrasocial and the social 

 animals. I beheve that a consideration of the facts to be presented 

 will allow us to place this important social factor more nearly in its 

 proper relation to other factors equally important. 



The problems dealt with in the present study are of interest also to 

 the large group of students of animal ecology. It is generally known 

 that ecology deals with the relations between the organism and its 

 environment. This environment is roughly divided into two parts— 

 the non-living and the Hving — which are commonly referred to as 

 the "physical" and the "biotic" elements of the environment. Of 

 these, the former has received particular attention at the hands of 

 modern animal ecologists, since such factors as light, hydrogen-ion 

 concentration, humidity, wind velocity, and temperature are more 

 or less readily and definitely measured, and since others, such as soil 

 type or the chemical composition of the waters of a lake or river, 

 though less readily analyzed, are still capable of being studied on a 

 quantitative basis. Meantime the analysis of the biotic relations of 

 the environment has lagged, probably on account of the greater 

 difficulties involved in the quantitative treatment of this exceedingly 

 complex part of the environment. Even so, marked progress has 

 been made in this analysis by recent students of the ecological rela- 

 tions within animal and plant communities (Smith, 1928; Shackle- 



