"I discovered one day," says he, "a Euphorbia, which supported in the middle of its stem a small sphere, to which it served as the axis. It was a case which the ants had constructed of earth. They issued forth from this by a very narrow opening made in its base, descended the stem, and passed into a neighbouring ants' nest. I destroyed one part of this pavilion, built almost in the air, so that I might study the interior. It was a little room, the vault-shaped walls of which were smooth and even. The ants had profited by the form of the plant to sustain their edifice. The stalk passed up the centre of the apartment, and for its timber-work it had the leaves. This retreat contained a numerous family of plant-lice, to which the brown ants came peacefully, to make their harvest, sheltered from the rain, the sun, and from other ants. No insect could disturb them; and the plant-lice were not exposed to the attacks of their numerous enemies. I admired this trait of industry; and I was not long in finding it again, in a more interesting character, in ants of different species. "Some red ants had built round the foot of a thistle a tube of earth, two inches and a half long by one and a half broad. The ants' nest was below, and communicated directly with the cylinder. I took the stalk, with what surrounded it, and all that the cylinder contained. That portion of the stem which was inside the earthen tube was covered with plant-lice. I very soon saw the ants coming out at the opening I had made at the base; they were very much astonished to see daylight at that place, and I saw that they lived there with their larvæ. They carried these with great haste to the highest part of the cylinder which had not been altered. In this retreat they were within reach of their plant-lice, and here they fed their young. "In other places many stalks of the Euphorbia laden with plant-lice rose in the very centre of an ant-hill belonging to the brown ants. These insects, profiting by the peculiar arrangement of the leaves of this plant, had constructed round each branch as many little elongated cases; and it was here they came to get their food. Having destroyed one of these cells, the ants forthwith carried off into their nests their precious animals; a few days afterwards it was repaired under my eyes by these insects, and the herd were taken back to their pens.