114 ZOOLOGY. 



part of their victims, we find the herding" of the bison, of deer, 

 and their allies for protection, whether by fighting together or 

 by the stationing of sentinels to give notice to the feeding herd 

 of the approach of danger. In still other forms, notably 

 among such insects as the bees and ants, there is a very intimate 

 and permanent union in social life. This is usually associated 

 with the instinct of home building, and thus a high degree of 

 division of labor with its great advantages becomes possible. 

 This is carried to such an extent that often polymorphic in- 

 dividuals result, much as in the organic colonies. In such cases 

 it is clear that the individual life comes to be bound up in the 

 success of the community. Such forms usually exert great 

 care for their young and develop a relatively high order of 

 intelligence. The principal social forms are the ants, of which 

 there are more than two thousand species ; some of the bees 

 and wasps; the termites, or so-called white-ants; beavers; 

 some monkeys and man. 



152. Library Exercise. Make a report on the social life of the honey- 

 bee, including the following points : the home ; the kinds of individuals, 

 their origin, and their work in the community; their food and its prepara- 

 tion; mode of caring for the young; swarming and its significance. Make 

 a similar report concerning some species of ant. Find facts concerning 

 the following topics : " ants' cows " ; slave-making among the ants ; army 

 ants ; the agricultural ant. 



153. Competition Among Animals of the Same Species 

 is not, for the most part, of a personal character except in the 

 case of the struggles of the males of polygamous animals. 

 The ordinary struggle for existence among them is merely 

 that of food-seeking, where all possess the same organs and 

 habits but in varying degrees of excellence. Those which have 

 the greater strength, hardiness, or intelligence are more likely 

 to get their portion of food at the expense of the weaker, and 

 thus to propagate their qualities. Sometimes however animals 

 live directly at the expense of their own species. Young 

 spiders before escaping from the cocoon in which they are 

 hatched devour each other, thus instituting an acute phase of 

 the struggle for existence in the place of the protection pre- 



