XXII AN EXCHANGE OF NESTS 309 



I offered her a cell in process of construction, and 

 she worked on with the same care and zeal as if the 

 work already done had been her own. If she were 

 bringing honey and pollen, I offered a cell partly 

 stored. Her journeys continued, with honey in her 

 crop and pollen underneath her body to complete 

 filling the store of another bee. 



Thus the bee does not suspect the exchange, nor 

 distinguish what is and is not hers. She thinks she 

 is continuing to work at a cell really her own. 



After leaving her for a time in possession of the 

 exchanged nest, I restored her own. The fresh 

 change passed unobserved ; her labour was continued 

 in the cell restored to her, at the point at which it 

 had arrived in the substituted one. Then I once 

 more substituted the strange nest, and still she per- 

 sisted in her labour. Thus alternating nests at the 

 same spot, I thoroughly convinced myself that the 

 insect cannot perceive the difference between that 

 which is her own and that which is not. Whether 

 the cell be hers or not, she works with equal fervour, 

 provided that the basis for the edifice — the stone — 

 remains in its original position. 



One may lend a livelier interest to the experiment 

 by using two neighbouring nests — work at which 

 is about equally advanced. I transpose them, placing 

 one where the other was ; the distance is hardly a 

 cubit. Despite this close neighbourhood, which allows 

 the bees to see both nests at once and choose be- 

 tween them, the two bees on arriving each immediately 

 alighted on the substituted nest and went on working 

 at it. We may change the two nests at pleasure ; 

 we shall still see the two mason bees keep to the 



