At any rate, it has been proved that these ruses are singularly invariable. In this connection I will mention an experiment which interested me greatly. Here are the particulars: at the moment when the Sphex is making her domiciliary visit, I take the Cricket left at the entrance to the dwelling and place her a few inches farther away. The Sphex comes up, utters her usual cry, looks here and there in astonishment, and, seeing the game too far off, comes out of her hole to seize it and bring it back to its right place. Having done this, she goes down again, but alone. I play the same trick upon her; and the Sphex has the same disappointment on her arrival at the entrance. The victim is once more dragged back to the edge of the hole, but the Wasp always goes down alone; and this goes on as long as my patience is not exhausted. Time after time, forty times over, did I repeat the same experiment on the same Wasp; her persistency vanquished mine and her tactics never varied. Having demonstrated the same inflexible obstinacy which I have just described in the case of all the Sphex-wasps on whom I cared to experiment in the same colony, I continued to worry my head over it for some time. What I asked myself was this: ‘Does the insect obey a fatal tendency, which no circumstances can ever modify? Are its actions all performed by rule; and has it no power of acquiring the least experience on its own account?’ Some additional observations modified this too absolute view. Next year I visit the same spot at the proper season. The new generation has inherited the burrowing-site selected by the previous generation; it has also faithfully inherited its tactics: the experiment of withdrawing the Cricket yields the same results. Such as last year’s Sphex-wasps were, such are those of the present year, equally persistent in a fruitless procedure. The illusion was simply growing worse, when good fortune brought me into the presence of another colony of Sphex-wasps, in a district at some distance from the first. I recommenced my attempts. After two or three experiments with results similar to those which I had so often obtained, the Sphex got astride of the Cricket, seized him with her mandibles by the antennæ, and at once dragged him into the burrow. Who was the fool now? Why, the experimenter foiled by the clever Wasp! At the other holes, her neighbours likewise, one sooner, another later, discovered my treachery and entered the dwelling with the game, instead of persisting in abandoning it on the threshold to seize it afterwards. What did all this mean? The colony which I was now inspecting, descended from another stock—for the children return to the site selected by their parents—was cleverer than the colony of the year before. Craft is handed down: there are tribes that are sharper-witted and tribes that are duller-witted, apparently according to the faculties of their elders. With the Sphex as with us, the intellect differs with the province.