94 MIND IN EVOLUTION CHAP. 



the nest being carefully made and sealed up empty! 1 A 

 single fact of this kind is enough to wreck the suggestion 

 that the nest-building of the wasp is a fully intelligent 

 process as we understand intelligence. If, again, a wasp 

 understood that her business was to store a nest with food, 

 she would hardly reject a suitable insect when she finds one 

 readytohand. But there are many such instances. Having, 

 for example, dropped a beetle in her disturbance at being 

 watched, a wasp let it lie for three days close by her web 

 without picking it up again. 2 The behaviour of others 

 was still more irrational. 



"While Cerceris was away hunting, some dry sand was thrown 

 into the nest and the entrance 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 en- 

 trance, 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. It 

 was evident that in one of the trips that we had seen her make 

 she could not reach directly to the cell which she was provision- 

 ing and dropped the victim at the place where she had to stop. 

 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 aban- 

 doned on the threshold, and the other was dropped half way in 

 neither served as food for larvae. What of that ? Cerceris had 

 given the sting that was enough. 



" At another time a nest, one of the cells of which was not 

 entirely provisioned, was destroyed at evening. On the next 

 morning Cerceris brought a newly stung bee and placed it in the 

 hole. On the following day she came again, charged with prey, 

 and dropped her bee, which rolled to the bottom of the excava- 

 tion. She had not brought the full number for provisioning the 

 nest. Instinct commanded her to bring them, and she obeyed, 

 but not knowing where to put them, let them fall." 3 



Such cases bring us back by a sharp turn to the con- 

 ception of instinct as a mechanism that must run down in 

 its own way. So does the following. A specimen of 

 P. marginatus is seen dragging a small spider along. 



1 P. 84. 2 Ib. p. 114. 3 P. 209. 



