SOCIAL EVOLUTION AS A BIOLOGICAL PROCESS 259 



trol the activities of the cells making up what we now 

 take as the individual element, command obedience 

 on the part of the interrelated members of an insect 

 community with equal strictness. 



A butterfly or a moth is primarily egoistic and unso- 

 cial in the ordinary sense during its entire life-history, 

 until the final reproductive act which has a value to the 

 species. The caterpillar larva devotes all of its energies 

 to feeding and growing, unconcerned with the final 

 duties of the moth with which it is connected just as 

 the indifferent unit of a young Volvox colony is related 

 to a reproducing member of the full-grown organism. 

 Now and then, it is true, species like the so-called tent 

 caterpillar are met with where numerous larvae spin 

 silken communal nests to which they retire at night 

 and in which they remain to molt. The pupa, like 

 the larva, is individualistic and employs its time in 

 producing the final adult form. The mature individual, 

 however, is constructed almost solely for the greater 

 purpose of perpetuating the species. Indeed the larger 

 silkworm moths do not and cannot feed, and their 

 value is only that of a device for keeping the race estab- 

 lished. Adult may-flies live only a few minutes, just long 

 enough to provide for the fertilization and deposition of 

 the eggs, although to prepare for these acts the young 

 individuals must have toiled for months ; the preparatory 

 time may amount to many years in such a case as the 

 seventeen-year locust. But nature is satisfied, as long 

 as the organic mechanisms obey her double command- 

 ment, ^^Live and grow so as to multiply." Like an 

 Amoeba, the solitary insect must be egoistic at first, in 

 order to be altruistic in a racial sense in its last days. 



