Arranged one by one, horizontally and at different heights, the cells occupy the basement of the house. They are oval cavities, three-quarters of an inch long, dug out of the clay mass. They end in a short bottle-neck that widens into a graceful mouth. They look like tiny vaccine-phials laid on their sides. All of them open into the passage. The inside of these little cells has the gloss and polish of a stucco which our most experienced plasterers might envy. It is diapered with faint longitudinal, diamond-shaped marks. These are the traces of the polishing-tool that has given the last finish to the work. What can this polisher be? None other than the tongue, that is obvious. The Halictus has made a trowel of her tongue and licked the wall daintily and methodically in order to polish it. This final glazing, so exquisite in its perfection, is preceded by a trimming-process. In the cells that are not yet stocked with provisions, the walls are dotted with tiny dents like those in a thimble. Here we recognize the work of the mandibles, which squeeze the clay with their tips, compress it and purge it of any grains of sand. The result is a milled surface whereon the polished layer will find a solid adhesive base. This layer is obtained with a fine clay, very carefully selected by the insect, purified, softened and then applied atom by atom, after which the trowel of the tongue steps in, diapering and polishing, while saliva, disgorged as needed, gives pliancy to the paste and finally dries into a waterproof varnish. The humidity of the subsoil, at the time of the spring showers, would reduce the little earthen alcove to a sort of pap. The coating of saliva is an excellent preservative against this danger. It is so delicate that we suspect rather than see it; but its efficacy is none the less evident. I fill a cell with water. The liquid remains in it quite well, without any trace of infiltration. The tiny pitcher looks as if it were varnished with galenite. The impermeability which the potter obtains by the brutal infusion of his mineral ingredients the Halictus achieves with the soft polisher of her tongue moistened with saliva. Thus protected, the larva will enjoy all the advantages of a dry berth, even in rain-soaked ground. Should the wish seize us, it is easy to detach the waterproof film, at least in shreds. Take the little shapeless lump in which a cell has been excavated and put it in sufficient water to cover the bottom of it. The whole earthy mass will soon be soaked and reduced to a mud which we are able to sweep with the point of a hair-pencil. Let us have patience and do our sweeping gently; and we shall be able to separate from the main body the fragments of a sort of extremely fine satin. This transparent, colourless material is the upholstery that keeps out the wet. The Spider's web, if it formed a stuff and not a net, is the only thing that could be compared with it.