The Mason-bees 



her nest when she started on her last jour- 

 ney, the nucleus of a store of food. Thence- 

 forward she behaves like her neighbour and 

 goes on carrying honey and pollen to the 

 warehouse which is not of her making. 



Restore the nests to their original places, 

 exchange them yet once again and both Bees, 

 after a short hesitation which the great dif- 

 ference between the two nests is enough to 

 explain, will pursue the work in the cell of her 

 own making and in the strange cell alternately. 

 At last the egg is laid and the sanctuary 

 closed, no matter what nest happens to be 

 occupied at the moment when the provision- 

 ing reaches completion. These incidents are 

 sufficient to show why I hesitate to give the 

 name of memory to the singular faculty that 

 brings the insect back to her nest with such 

 unerring precision and yet does not allow her 

 to distinguish her work from some one else's, 

 however great the difference may be. 



We will now experiment with Chalicodoma 

 muraria from another psychological point of 

 view. Here is a Mason-bee building; she is 

 at work on the first course of her cell. I 

 give her in exchange a cell not only finished 

 as a structure, but also filled nearly to the top 

 64 



