DIFFERENTIATION OF INDIVIDUALS AND ADAPTATION 121 



156. 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 preparation; 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. 



157. 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 ex- 

 pense 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 prepared by parental care. Many fishes 

 are known to devour their own young. We have all had occa- 

 sion to wonder what becomes of the small frogs in a box contain- 

 ing large ones. 



The struggle between the males for the possession of the 

 females has resulted in the development of many interesting 

 adaptations. The struggle may take the form of actual combat 

 in connection with which organs of offense and defense are 

 found. Such are the horns, tusks, spurs, manes, and even the 

 excessive size of the males as compared with the females. Mani- 

 festly the same qualities which make a male a formidable rival 

 to another are likely to be of service to himself, his mates, and 

 his young, and thus to the species, in protecting them from the 

 attack of their enemies among other species. The competition 

 between males is not all of this stressful kind, however. It is 

 believed by many naturalists that, in those instances where 

 simple mating rules, those males with the most striking colors, 

 pleasant voices, and winning ways displace their less favored 

 rivals and thus tend to accumulate by natural (sexual) selection 

 the adaptations of this class. 



