168 ANIMAL LIFE 



88. Division of labor and basis of communal life. We have 

 learned in Chapters II and IV that the complexity of the 

 bodies of the higher animals depends on a specialization or 

 differentiation of parts, due to the assumption of different 

 functions or duties by different parts of the body ; that the 

 degree of structural differentiation depends on the degree 

 or extent of division of labor shown in the economy of the 

 animal. It is obvious that the same principle of division of 

 labor with accompanying modification of structure is the 

 basis of colonial and communal life. It is simply a mani- 

 festation of the principle among individuals instead of 

 among organs. The division of the necessary labors of life 

 among the different zooids of the colonial jelly-fish is plain- 

 ly the reason for the profound and striking, but always 

 reasonable and explicable modifications of the typical polyp 

 or medusa body, which is shown by the swimming zooids, 

 the feeding zooids, the sense zooids, and the others of the 

 colony. And similarly in the case of the termite commu- 

 nity, the soldier individuals are different structurally from 

 the worker individuals because of the different work they 

 have to do. And the queen differs from all the others, be- 

 cause of the extraordinary prolificacy demanded of her to 

 maintain the great community. 



It is important to note, however, that among those ani- 

 mals that show the most highly organized or specialized 

 communal or social life, the structural differences among 

 the individuals are the least marked, or at least are not the 

 most profound. The three kinds of honey-bee individuals 

 differ but little ; indeed, as two of the kinds, male and 

 female, are to be found in the case of almost all kinds of 

 animals, whether communal in habit or not, the only unu- 

 sual structural specialization in the case of the honey-bee, is 

 the presence of the worker individual, which differs from 

 the usual individuals in but little more than the rudimen- 

 tary condition of the reproductive glands. Finally, in the 

 case of man, with whom the communal or social habit is so 



