RESPONSIVE LIFE OF ORGANISMS 



477 



find no food. The fly does not possess even such 

 perceptive faculties as would enable it to distinguish 

 between a flower and a dead carcass. The fly knows neither 

 carcass nor flower, but only a certain kind of olfactory 

 stimulus that may come from either. 



FIG. 267. A mistake of instinct. The kinglet, seeking the larvae of the burdock 

 moth (see fig. 247 on page 425) is ensnared by the hoods of the burdock heads. 



Study 62. Experiments on the case building instincts of 



caddis-worms. 



Materials needed : A supply of living caddis- worms, that 

 may be kept in proper receptacles at proper temperature 



