390 ANNUAL EEPOKT SMITHSONIAN INSTITUTION, 1925 



Diirin;^- (he period oi the first divisions in the developing insect 

 egg, tliere is no evidence to sho^Y that any cell may not become either 

 a body cell or a germ cell, or that any particular body cell has from 

 the beginning a special destin3\ When the body cells later become 

 organized into layers and gron])s, they become more and more re- 

 stricted in their reproductive powers, each group forming only cer- 

 tain organs and tissues of the future animal. In the adult stage even 

 this j)()wer is largely lost in the cells of higher animals, Avhich can 

 now multiply only to the extent of healing wounds. Lower in the 

 scale of organization, however, lost members of the body can be 

 regenerated from a stumj), or even the greater part of the body may 

 be re-formed from a fragment. At last, though, there comes a time 

 when the vitality of the body cells is lost, or is completely sup- 

 pressed, and the animal dies. 



Though the body cells are by nature merely the servants of the 

 germ cells, we look upon the structure that they form as the reason 

 for the existence of the germ cells, because it is the visible, sentient 

 animal in which are developed all the powers of reaction to external 

 stimuli, the instincts, self-consciousness, and intelligence that is 

 potential in the germ cell. But these faculties are all developed for 

 the i3urpose of maintaining the germ cells, for bringing them to- 

 gether, for nourishing, protecting, and educating the offsprmg. No 

 creature, therefore, according to the plan of nature, lives for itself; 

 its whole reason for existence is the next generation. This does not 

 mean, however, that every individual of a species should be a repro- 

 ductive individual. Among the social insects, the ants and bees, for 

 example, certain individuals are designed to be accessor}^ to the re- 

 productive individuals. These are the so-called workers and soldiers 

 that build the nest or comb, protect the community from invasion, 

 attend to the collecting and storing of food, rear and feed the 

 young — members of the community which, in short, are indisi^ensible 

 to it through tlicir services to the reproducing castes and to the 

 offspring of the latter. 



Since the germ cells and the body cells of each individual are pro- 

 duced side by side, and not one from the other, heredity, as a conse- 

 quence, is not directly from one generation to the next, but between 

 alternate generations. In figure 11 it is seen that the germ cells and 

 tlie body cells of generation C, for example, find their common ances- 

 tor not in the parent generation B, but in a germ cell derived from 

 the grandparent generation A, which cell is contained and deA^eloped 

 in B. The common resemblance between parent and offspring, then, 

 is due to the dcA^elopmental influences embodied in the germ cells, 

 which produce similar results in the body cells of successive genera- 

 tions, and not to influences exerted by the body cells on the germ 



