XIX 



THE RETURN TO THE NEST 



The Ammophila digging her well late in the day 

 leaves her work after stopping the entrance with a 

 stone, flits away from one flower to another, goes 

 into a new neighbourhood, and yet next day can 

 return with a caterpillar to the abode hollowed out 

 the evening before, notwithstanding her want of 

 acquaintance with the locality — often new to her ; the 

 Bembex, loaded with prey, alights with almost mathe- 

 matical precision on the threshold of a dwelling 

 blocked by sand and rendered uniform with the rest 

 of the sandy surface. Where my sight and memory 

 are at fault, theirs have a certainty verging on 

 infallibility. One would say that the insect possessed 

 something more subtle than mere recollection — a kind 

 of intuition of locality with which nothing in us 

 corresponds — in short, an indefinable faculty which I 

 call memory for lack of any other expression by 

 which to designate it. The unknown cannot be 

 named. In order to throw if possible a little light 

 on this point in the psychology of animals I instituted 

 a series of experiments, which I will now describe. 

 The first had for its subject Cerceris tuberculata, 

 258 



