224 CHILDHOOD OF ANIMALS 



first place imperative that this period of feebleness should be passed 

 through as quickly as possible. And evidence of a tendency to 

 shorten and simplify the development of the embryo or of the 

 larva, to remove all stages that have ceased to be useful and to 

 make straight the path from egg to adult is to be found in every 

 group of the animal kingdom, but is increasingly plain in the higher 

 groups and the higher members of every group. 



The shortening and simplification are most complete in the em- 

 bryonic stages of development, whether these take place within 

 an eggshell or in the body of the mother. In free-living larvae, 

 or in active young, protection is often obtained by new organs, 

 special habits, peculiar pattern and coloration that may have no 

 reference to the past history of the animal and no direct bearing 

 on its adult shape and form. Larval organs, habits and coloration 

 are not infrequently new interpolations in the life-history, the sole 

 purpose of which is to protect the larvae and give them a chance 

 of coming to maturity. I confess that when I was beginning to 

 collect materials about young animals, I hoped to find that youthful 

 characters would sometimes show the direction in which the race 

 might be supposed to be going to develop. I thought that I should 

 find the exuberant vitality of youth displaying itself in new ways, 

 some of which might turn out to be useful and come to be adopted 

 by the adult. I can find no trace of such prophetic or tentative 

 efflorescence in structure, coloration or pattern, although, as I 

 shall show later, there is something comparable with it in the mental 

 qualities of youth. The physical characters of youth are sternly 

 economic. Special organs, new or old, are present because they 

 make it more possible for the creatures to escape the destruction 

 that is always treading on the heels of the young. Pattern and 

 coloration are either simply the ancestral garb of the parents still 

 retained, or the direct results of growth, or occasionally, and especially 

 in caterpillars, devices for the immediate protection of the young. 

 The youth of most animals is too hampered by the past, too harassed 

 by the present, for experiment in structure or coloration to be 

 possible. 



The amazingly heavy mortality that presses on the young is 

 met in a great many cases by the enormous size of the families. I 

 have given instances of the almost incredible number of eggs that 

 are laid, of young animals that are turned adrift, a few of which 

 escape the perils that beset them and live to maintain the species. 

 This spendthrift fashion of reproduction, which bears witness to 



