48 THE SOCIAL LIFE OF ANIMALS 



elation can be shown, from the sexual forms that 

 meet but once and for a brief moment to the ter- 

 mite kings and queens that live together for years. 

 Also all stages exist in the evolution of the associa- 

 tion of parents with offspring, from the insects like 

 the female walking-stick, which deposits eggs as she 

 moves about and pays no more attention to them, 

 to the ants and bees whose worker offspring spend 

 their entire lives in the parental colony or some 

 colony budding off from it. 



While the extension of family relations is very 

 obviously one potent method by which social life is 

 developed to a high level, there are other social 

 groupings which also deserve consideration in con- 

 nection with the problem as to the method of evo- 

 lution of social life. Schools of fish arise, for exam- 

 ple, under conditions in which there is no associa- 

 tion with either parent after the eggs are laid. At 

 times the eggs may be so scattered in the laying that 

 the schools form from unrelated individuals. Here 

 the schooling tendency seems to underlie rather 

 than grow out of family life. The mixed flocks (22) 

 of tropical birds which are composed of many spe- 

 cies obviously did not grow directly from family 

 gatherings, and the groups of stags of Scottish deer, 

 probably the original stag parties, (38) appear to 

 give evidence of a grouping tendency independent 



