Why were you not with me, venerated master, on the banks of the Aygues, with their stretches of pebbles, dry for three parts of the year, and an enormous torrent when it rains? I would have shown you something far better than the fugitive escaped from your pincers. You should have seen, and shared my surprise thereat, not the short flight of a mason bee, which, carried into a room near at hand, escapes and returns straight home in a neighbourhood familiar to her, but long journeys by unknown ways. You would have seen the bee, carried away by me to a long distance, return with a geographical precision which the swallow would not disown, or the martin, or the carrier-pigeon, and you would have asked yourself, as I did, what inexplicable knowledge of the map of the country guides this mother in seeking her nest. Let us come to the facts. We must repeat on the mason bee my earlier experiments with the Cerceris—namely, carrying the insect in darkness far from the nest, marking and setting it free. In case any one should wish to repeat the experiment, I will explain my method of operation, which may make it easier for a beginner. The insect destined for a long journey must of course be captured with certain precautions. No nippers, no pincers which might maim a wing, strain it, and endanger power of flight. While the bee is absorbed in work within her cell, I cover the latter with a little glass tube. As she flies out she goes into this, and thus, without touching her, I can transfer her to a twist of paper and close it quickly. A botanical tin serves as a means of transporting the captives, each in its paper prison. It is on the spots chosen as starting-places that the most delicate operation takes place—namely, marking each captive before freeing her. I use chalk powdered fine and moistened with a strong solution of gum arabic. Dropped somewhere on the insect with a straw, it leaves a white mark, which dries quickly and adheres to the bee’s fleece. If a mason bee has to be marked, so as to distinguish her from another in an experiment of short duration, such as I shall presently describe, I only touch the tip of the abdomen with a straw charged with colour while the insect is half inside the cell, head down-wards. The bee does not notice the slight touch and works on undisturbed; but the mark is not very durable, nor at a spot favourable for its preservation, since the bee frequently brushes her body to detach pollen, and sooner or later effaces it. It is therefore in the very middle of the thorax—between the wings—that I drop the gummed chalk.