82 NATURE SKETCHES IN TEMPERATE AMERICA 



influence of kataplexy or hypnotism, this state being induced 

 by fright. Darwin looked upon the instinct of "shamming 

 dead" as simply the result of remaining motionless and thus 

 inconspicuous in the presence of its enemies; this instinct 

 having developed by natural selection without ever having 

 been of an intelligent nature. Those individuals which were 

 least inclined to run away from enemies being preserved rather 

 than those which rendered themselves conspicuous by move- 

 ment. Romanes ' says, "There seems to be at least not more 

 difiiculty in developing an instinct to remain motionless under 

 certain circumstances, than in developing one to run away, 

 and as a matter of fact, all animals which are protectively 

 colored have either as cause or sequence developed their 

 instincts in the former direction." 



In the above word sketch,! have stated that the eggs of these 

 insects bear a clo.se resemblance to the seed of plants, and 

 secondly, that the young show remarkable adaptation to 

 a life on the leaves, their attenuate bodies being deceptively 

 like the venation of the leaves. Finally, I will now call attention 

 to the fact that the adults are protected in their resemblance to 

 twigs even to the minutest detail. In the fall the sexes are 

 found together in large numbers, in pairs, often on the bark 

 of the forest and fruit trees. Again, I have found them on 

 such shrubs as the sumach; here they are all but invisible as 

 they hold on the main stems. When I discover them .sometimes 

 by accident, I often marvel that they are ever seen at all by 

 human eyes, so close do their bodies imitate the twigs. Even 

 the leaf scars are wonderfully represented. And why, may I ask, 

 do these in.sects choose as a place of refuge the very spot on 

 the sumach where there are dead branches near the main stem? 



Here is certainly a group of insects for the naturalist to work 

 on. The problems presented are certainly accessible })y experi- 

 mental research, and if they are coupled with observations in 

 tlie great biological experiment grounds of nature, there is 

 still room for interesting discoveries. Such adaptations as 

 are shown in the form and color of the walking-sticks are the 

 most striking of any in our temperate fauna. They doubtless 

 ofTer the most powerful argument in favor of natural selection. 

 ' "Mental Evolution in .\nimals." 



