98 INSTINCT 



With animals which go through a profound metamorphosis 

 in the course of their development we find correspondingly 

 great changes in instinctive behavior. Nothing could be 

 more dissimilar than the instincts of the stealthy dragon- 

 fly nymph which prowls among the debris at the bottom of 

 ponds and streams for its food ; and the graceful and rapid 

 darting of the full fledged dragon-fly as it chases its prey 

 through the air. The transition between these two stages 

 is very abrupt. When ready for its final moult the dragon- 

 fly nymph crawls upon the stem of some plant or upon a 

 stone, its skin splits down the back, and out comes the imago, 

 which needs only to dry its wings a little to be ready for its 

 vita nuova in the world of sunshine. The difference between 

 the behavior of the crawling, gnawing caterpillar and the 

 active honey sucking butterfly; of the helpless wriggling 

 grub and the honey bee; of the free swimming larva and the 

 worm that burrows in the sand of the seashore are instances, 

 out of thousands that might be given, of the great differences 

 in instinctive behavior at different periods of life in forms 

 which undergo marked metamorphoses in structure. 



Where animals are hatched in the form of the adult we find 

 little change in instinct. The young trap door spider, accord- 

 ing to Moggridge, constructs its tiny tubular dwelling with its 

 ingeniously fitted trap door in almost a perfect miniature of 

 the adult nest. Montgomery finds that the young of the 

 orbweavers Epeira scolpetaria and E. marmorea spin, at their 

 very first attempt, a diminutive web of the same degree of 

 perfection as that of the full grown spider. Here, as in the 

 case of the amphipod previously described, the young closely 

 resemble the older individuals. Where the change of form 

 is greater, as in insects with a gradual or incomplete meta- 

 morphosis, there is a gradual change of instinct. The be- 

 havior of the tadpole graduates insensibly into the very 



