The Mason-bees 



and drives the probe into all of them Indiffer- 

 ently, is this not an evident proof that smell 

 is no guide whatever to her in her search? 

 Other considerations, when I was treating of 

 the Hairy Ammophila, enabled me to assert 

 that the antennae have no olfactory powers. 

 To-day, the frequent mistakes of the Leucos- 

 pls, whose antennae are nevertheless constantly 

 exploring the surface, make this conclusion 

 absolutely certain. 



The perforator of clay nests has, so It seems 

 to me, delivered us from an old physiological 

 fallacy. She would deserve studying, if for 

 no other result than this; but her interest Is 

 far from being exhausted. Let us look at her 

 from another point of view, whose full Im- 

 portance will not be apparent until the end; 

 let us speak of something which I was very 

 far from suspecting when I was so assidu- 

 ously watching the nests of my Mason- 

 bees. 



The same cell can receive the Leucospis' 

 probe a number of times, at Intervals of se- 

 veral days. I have said how I used to mark 

 in black the exact place at which the laying- 

 implement had entered and how I wrote the 

 date of the operation beside it. Well, at 

 298 



