262 INSECT LIFE 



XIX 



as quick when, having reached a certain height at which 

 they can in some sort take their bearings, they launch 

 themselves with all their power of wing towards that 

 part of the horizon where are their nests ? Is it 

 memory which traces their aerial way across regions 

 seen for the first time ? Evidently not. It is not 

 possible to recollect the unknown. The Hymen- 

 opteron and the bird know nothing of their surround- 

 ings ; nothing can have taught them the general 

 direction which they followed when carried thither, 

 for it was in the darkness of a closed box that the 

 journey was made. Locality, orientation, — all is un- 

 known, and yet they find their way. They have 

 then as guide something better than simple memory — 

 a special faculty, a kind of topographic consciousness 

 of which we can form no idea, possessing nothing 

 analogous to it. 



I am now about to establish experimentally how 

 subtle and precise is this faculty in the narrow cycle 

 where it is applied, and also how limited and obtuse 

 when it has to move out of habitual conditions. Such 

 is the invariable antithesis of instinct. 



A Bembex, actively engaged in feeding her larva, 

 has left her burrow. She will return immediately 

 with the product of the chase. The entrance is 

 carefully stopped with sand — swept backward by 

 the insect before departing. Nothing distinguishes 

 it from the rest of the sandy surface. But this 

 offers no difficulty to the Hymenopteron, who finds 

 her doorway again with a sagacity which I have 

 already described. Let us plan some treachery ; 

 let us perplex her by altering the state of the place. 

 I cover the entrance with a flat stone as large as 



