The plasterer and the mason have their trowels. In the same way, the grub, that zealous repairer of breaches made in its home, has a trowel of its own. The last segment is lopped off slantwise and carries on its dorsal surface a sort of inclined plane, a broad disk surrounded by a fleshy pad. In the middle of the disk is a slit, forming the cementing-aperture. There you have your trowel, a most respectable one, flattened out and supplied with a rim to prevent the compressed matter from flowing away uselessly.
As soon as the mass of plastic matter has been emitted, the levelling- and compressing-instrument sets to work to introduce the cement well into the irregularities of the breach, to push it right through the thickness of the ruined portion, to give it consistency and smooth it. After this trowel-work, the grub turns round: it comes and finishes the job with its wide forehead and improves it with the tip of its mandibles. Wait a quarter of an hour; and the repaired portion will be as firm as the rest of the shell, so quickly does the cement set. Outside, the repairs are betrayed by the irregular projections where the stuff has been forced out, the part which the trowel could not reach; but, inside, there is no trace of the breakage: the usual polish has been restored at the damaged spot. A plasterer stopping a hole in one of our walls could produce no better piece of work.
Nor do the grub’s talents end here. With its cement it becomes the mender of pots and pans. Let me explain. I have compared the outside of the pear, which, when pressed and dried, becomes a stout shell, with a jar containing fresh food. In the course of my excavations, sometimes made on difficult soil, I have happened occasionally to break this jar with an ill-directed blow of my trowel. I have collected the potsherds, pieced them [[88]]together, after restoring the grub to its place, and kept the whole thing united by wrapping it in a scrap of newspaper.
On reaching home, I have found the pear put out of shape, no doubt, and seamed with scars, but just as solid as ever. During the walk, the grub had restored its ruined dwelling to condition. Cement injected into the cracks joined the pieces; inside, a thick plastering strengthened the inner wall, so much so that the repaired shell was quite as good as the untouched shell, except for the irregularity of the outside. In its artistically-mended stronghold the grub found the peace essential to its existence.
The time has come to ask ourselves the reason for this plasterer’s craft. Destined to live in complete darkness, does the larva stop the cracks made in its house in order to avoid the unwelcome intrusion of the light? But it is blind. There is no trace of an organ of sight on its yellowish headpiece. The absence of eyes, however, does not authorize us to deny the influence of the light, an influence which perhaps is vaguely resented by the grub’s delicate skin. Proofs are required. Here they are.
I manage to make my breach almost in the dark. The little light that remains is just sufficient to guide my house-breaking-implement. When the opening is made, I at once lower the shell into a dark box. A few minutes later, the hole is stopped. Despite the darkness in which it found itself, the grub has thought fit to seal up its cell.
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 [[89]]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 [[90]]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.