INSTINCT AND CONSCIOUSNESS OF FINALITY. 41 



danger simulate death and drop on the ground do ex- 

 actly the same if instead of firm ground there is a pool 

 of water below them. Even ants, in spite of their high- 

 ly developed faculty of adaptation, do not act less 

 stupidly. Generally speaking they adopt in observa- 

 tion nests the same line of instinctive actions which 

 were useful to them in their natural state, although in 

 the changed conditions those actions are often useless 

 and even harmful. 



Instances such as these could be multiplied indefi- 

 nitely. At present let us add but two striking illus- 

 trations which Peckham enumerates as "errors of in- 

 stinct. ' ' Cerceris ornata is the name of a solitary wasp, 

 which is known to kill certain bees of the genus Haly- 

 ctus by means of its sting, to carry them into its nest 

 of sand and place an egg upon the ventral side of 

 the bee. One day "while Cerceris was away hunting, 

 some dry sand was thrown into the nest, and the en- 

 trance was then stopped with damp sand. She returned 

 laden with prey, and seeing herself forced to resume 

 the profession of a miner, abandoned her victim, cleared 

 the entrance, penetrated within, came out again and 

 flew off in search of new prey. After two successive 

 trips she penetrated a third time into her dwelling and 

 began to reject the dry sand which had been thrown in. 

 In the midst of this sand was a bee (which she had drop- 

 ped before). Presently the wasp flew away. The hours 

 passed on and she returned without a bee, entered and 

 threw out the other one which she now considered an 

 encumbering object. Thus of two victims which were 

 procured with great trouble, one was abandoned on 

 the thresh-hold, and the other was dropped halfway 



