The Mason-bees 



time that the crossing is taking place. Let 

 us now see what will happen when the formic 

 scent, if there really be one on the trail, is 

 replaced by another, much stronger odour, one 

 perceptible to our own sense of smell, which 

 the first is not, at least not under present 

 conditions. 



I wait for a third sortie and, at one point 

 in the road taken by the Ants, rub the ground 

 with some handfuls of freshly-gathered mint. 

 I cover the track, a little farther on, with the 

 leaves of the same plant. The Ants, on their 

 return, cross the section over which the mint 

 was rubbed without apparently giving it a 

 thought; they hesitate in front of the section 

 heaped up with leaves and then go straight 

 on. 



After these two experiments, first with the 

 torrent of water which washes away all trace 

 of smell from the ground and then with the 

 mint which changes the smell, I think that we 

 are no longer at liberty to quote scent as the 

 guide of the Ants that return to the nest by 

 the road which they took at starting. Further 

 tests will tell us more about it. 



Without interfering with the soil, I now 

 lay across the track some large sheets of 

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