In small jars packed full of provisions, I bring up larvæ taken from their native pear. A pit is dug in the mass of foodstuffs, ending at the bottom in a hemisphere. This cavity, representing about the half of the pear, will be the artificial cell given in exchange for the natural one. I put the grubs on which I am experimenting into separate cells. The change of residence produces no appreciable anxiety. Finding the food of my selecting very much to their taste, they bite into the walls with their customary appetite. Exile in no way perturbs those stoical stomachs; and my attempts at breeding are pursued unchecked. A remarkable thing now happens. All my transplanted ones work little by little to complete the round nest of which my pit represented only the lower half. I have provided the flooring. They propose to add a ceiling, a dome, and thus to shut themselves up in a spherical enclosure. The materials are the putty supplied by the intestines; the building-tool is the trowel, the inclined plane of the final segment. Soft bricks are laid on the margin of the well. When these have set, they serve as a support for a second row, sloping slightly inwards. Other rows follow, marking the curve of the general structure more and more distinctly. Also, from time to time, a wriggle of the hinder part assists in determining the spherical conformation. In this way, without any supporting scaffold, without the cradle indispensable to our architects in building an arched roof, a commanding dome is obtained, built upon space and completing the sphere which I began. Some of them shorten the work. The glass wall of the little jar occasionally comes within range. Its smooth surface suits the taste of these fastidious polishers; its curve, to a certain extent, coincides with that of their plan. They make use of it, doubtless not from economy of labour and time, but because, to their mind, the smooth round wall is a thing of their own making. In this way there is reserved, on the sides of the cupola, a large glazed window which answers my purpose admirably. Well, the grubs which, all day long and for weeks on end, receive the bright light of my study through this window of mine keep as quiet as the others, eating and digesting, and never trouble to shut out any unwelcome rays with a blind made of their putty. We may take it therefore that, when the larva so eagerly closes the breach which I have made in its chamber, its object is not to protect itself from the light. Does it fear draughts then, when it scrupulously fills up the least cranny through which the air might enter? This again is not the solution. The temperature is the same in my room and in the grub’s; besides, when I perpetrate my burglaries, the atmosphere in my study is absolutely still. I do not examine the prisoner in a gale, but in the calm of my workroom, in the even profounder calm of a glass jar.