An ingenious Fly-trap is employed in our homes. It consists of a water-bottle with an opening at the bottom and standing on three low supports. Inside, some soap-suds form a ring-shaped lake around the orifice. A lump of sugar, placed beneath the entrance, acts as the bait. The Flies make for the sugar. On leaving it, seeing the light above them, they rise with a vertical flight and enter the trap, where they wear themselves out, beating their wings against the transparent wall. All perish by drowning, because they are incapable of the rudimentary notion of going out by the way they came. Even so with the Wasps under my bell-glass: they know how to get in, but do not know how to get out. On ascending from their burrow, they go to the light. Finding broad daylight in their transparent prison, they consider their aim accomplished. An obstacle checks their flight, it is true; no matter: the whole area is brightly lit up; and this is enough to delude the prisoners, who, despite the continual warning of their collisions with the glass, endeavour, obstinately and without attempting anything else, to fly farther in the direction of the luminous void. The Wasps returning from the fields are in a different situation. They are passing from light to darkness. Moreover, even without the intervention of the experimenter’s wiles, they are sure occasionally to find the threshold of their dwelling obstructed by fallen earth, the result of rain or of the feet of the passers-by. The next action of the homing Wasps is bound to follow: they search about, sweep, dig and end by finding the entrance-tunnel. This power of scenting their house through the soil and this eagerness to clear the doorway of their dwelling are innate aptitudes: they form part of the resources bestowed upon the species for its preservation in the midst of daily accidents. Here there is no need of reflection or calculation: the earthy obstacle has been familiar to one and all since Wasps first came into the world. They therefore scrape and go in. At the foot of the bell-glass, the same order of things obtains. Topographically, the position of the Wasps’-nest is perfectly well-known; but direct access has become impossible. What is to be done? After a brief hesitation, the process of digging and clearing is adopted according to ancient custom; and the difficulty is overcome. In short, the Wasp knows how to reenter her home, in spite of certain obstacles, because the action here accomplished conforms with what is always done in similar circumstances and does not call upon the shadowy intellect for any fresh gleam of light.