This is how, in the vast majority of cases, things happen under normal conditions. Almost all the pears that I dig up in the fields have rinds and are unpolished, some more, others less. If we put on one side the inevitable incrustations due to the carting-process, these blemishes would seem to point to a prolonged rolling in the interior of the subterranean manor. The few which I find perfectly smooth, especially those wonderfully neat specimens furnished by my cages, dispel this mistake entirely. They show us that, when the materials are collected near the burrow and stored away unshaped, the pear is modelled wholly without rolling; they prove to us that, in other cases, the lines of earth and grit on the outside of the ball are not a sign of its having been rolled to and fro in the workshop, but are simply the marks of a fairly long journey on the surface of the ground. To be present at the construction of the pear is no easy matter: the mystery-loving artist obstinately refuses to do any work as soon as the light reaches her. She needs absolute darkness for her modelling; and I need light if I would see her at her task. It is impossible to unite the two conditions. Let us try, nevertheless; let us catch some glimpses of the truth whose fulness eludes our vision. The arrangements made are as follows: I once more take the big jar. I cover the bottom with a layer of earth two or three inches deep. To obtain the transparent workshop necessary for my observations, I fix a tripod on the earthy layer and, on this support, about four inches in height, I place a round piece of deal of the same diameter as the jar. The glass-walled chamber thus marked out will represent the roomy crypt in which the insect works. A piece is scolloped out of the edge of the deal block, large enough to permit of the passage of the Beetle and her ball. Lastly, above this screen, I heap a layer of earth as deep as the jar allows. During the operation, a portion of the upper earth falls through the opening and slips down to the lower space in a wide inclined plane. This was a circumstance which I had foreseen and which was indispensable to my plan. By means of this slope, the artist, when she has found the communicating trap-door, will make for the transparent cell which I have arranged for her. She will make for it, of course, only provided that she be in perfect darkness. I therefore make a cardboard cylinder, closed at the top, and place it over the glass jar. Left standing where it is, the opaque sheath will provide the dusk which the insect wants; suddenly raised, it will give the light which I want.