94 INSTINCT 



the occupant. In its nest Amphithoe lies in wait for prey, 

 ready to dart out upon any small creature which touches 

 the ends of its long antennae. 



The activities of the adult Amphithoe, with the exception of 

 those concerned in reproduction, are almost exactly parallelled 

 by those of its young. I have taken the eggs from the mater- 

 nal brood pouch shortly before hatching and kept them 

 isolated in individual dishes. For some time after emerging 

 from the egg the young were weak and had imperfect control 

 of their movements, which were jerky and irregular. Soon the 

 minute creatures could crawl and swim much like the adults, 

 and the next day they began constructing nests which were 

 the same in shape as those formed by their parents. The 

 attitudes in the nest, the waving of the antennae, the beating 

 of the swimmerets, the restless movements of the legs and 

 mouth parts, springing after food, belligerency toward 

 passers by, the little unobtrusive signs of timidity, the 

 reversal of position in the nest on the approach of danger 

 and the general behavior outside of the nest were, on the 

 next day after hatching, almost exactly the same as in older 

 individuals. The only differences in behavior were due to 

 the feebleness of the young and their imperfect control of 

 their movements. The young are hatched with all the 

 instincts necessary fully to equip them for the business of 

 life. No experience is necessary to teach them what is ad- 

 vantageous for them to do. 



It is this skill and apparent foresight exhibited in instinc- 

 tive behavior that gives rise to a popular notion that animals 

 are somehow mysteriously endowed with a > knowledge of 

 those things which are necessary for their life. It is some- 

 times asserted that young ducklings will make for the nearest 

 water before they have gained any experience of the neighbor- 

 hood and in the absence of any signs by which the presence 



