arrangement. For the fabric of the nest is thus materially strengthened, by substituting, at this vital point, a hard, dry, light flooring for the loose, damp comb, which is almost ready to fall to pieces by its own weight.

When a new stage is to be constructed, the wasps begin by raising the walls of two or three adjoining cells in the centre of the lowest comb. From these diverging roots a round cord is drawn out, as it were, on the end of which little cells are made, just as on the end of the footstalk from which the nest originally sprung. As each cell takes shape an egg is deposited in it, so as to lose no time; and while its walls are gradually rising, the comb is gradually spreading, by concentric rings of cells. The mother wasp follows close on the traces of the worker, and the circles of larvæ of the same age shew the system on which the comb has been made. As the comb spreads, new stays are let down to support the weight increasing with the width. Meanwhile the expansion of the case keeps exact pace with the lateral growth of the comb; the old case is nibbled away within, and new paper is laid on outside, so as to make room all round the edge. And, before each stage has attained its full dimensions, another has been commenced below it, just in the same

manner.

There is something in all this very different to the economy of a bee-hive. There all the building instinct is concentrated in one point, and the only variety which the work offers, beyond the distinction of large and small cells, is the occasional appearance of a queen cell, disfiguring the symmetry of the

comb, and a sign of coming political disturbance. But in a wasp's nest the most varied building operations are going on simultaneously. The case has to be made, and the foundations—reversing the application of this term--constantly attended to. And as all has to be done in a few weeks, and time is very valuable, what presses most must be done first; and so the cells are merely sketched out in the first instance, but not built up till opportunity allows. And the social life of the insects corresponds. The bee-hive has its type, political excitement and all, in a flourishing manufacturing town; the wasps' nest finds its parallel on the outskirts of civilization, in the ready and versatile industry of those who live with their lives in their hands.

In many respects wasps are more easily watched in their proceedings than bees. With a little care and patience we may trace the exact process by which the outer case of a wasp's nest is built. But the internal economy is most jealously shut out from observation; we cannot study this as accurately as in a beehive. We may watch marked wasps come in and go out again, but we cannot tell what is going on inside all the while. For the first effort of the swarm is to surround all their work, and exclude all curious eyes, by a thick covering of paper. I have never seen, after watching two active swarms for a long time, the actual process of building a cell; but Mr. Newport * was more fortunate in the observation of his hornets, and describes the process as identical with that by which the outer case is made. The materials are laid on at the edge of the cell-wall, Op. cit. Trans. Entom. Soc.,' Vol. III, p. 189.

in the same way; but they are rather finer, and the work is more regular, than in the case of the nest. But though we cannot see all their proceedings just when we wish, the results are easily intelligible. By the indications of the variegated colours of the materials, and by the line of fracture when we tear up the softened cells, the details of their construction can be readily made out. The microscope tells us that the comb is made of the same materials as the case, but the paper is perhaps rather thicker, and of a closer texture. In the first beginning of the nest we saw how the four original cells took the form of so many little pockets attached to the footstalk; and this is still just the form which they take at the edge of the growing comb;-little pouches, with three straight sides where they fit on the cells already built, and one longer curved wall on the outer face. As the cell-wall rises, and the little pouch takes its place in the ranks as a cell, its transverse section displays a regular rectilinear hexagon; and the surface of a finished wasps' comb presents a series of as beautifully symmetrical hexagons as the comb of the honey-bee. But, for this result, it is necessary that the work should go on regularly. In the combs of a second nest, where the work has been carried on hurriedly, and under the guidance of many mistresses, the form of the cells is very irregular, round or square cells, irregular hexagons, and occasional intercellular spaces being often met with. And, generally speaking, the outermost cells of all combs, by whatever species they may be made, are not constructed with the same geometrical precision as the central cells. The free wall is either a seg

ment of a small circle or, if angular, the angles are rounded off and irregular. Judging at least from the specimens in my cabinet, including nests of several varieties of Polistes, Raphigaster, and Icaria.

The regular form of the cells of the honey-bee has long attracted attention, and the fact has been settled, beyond all question, that they are built with the strictest mathematical accuracy, as equilateral and equiangular hexagonal tubes. The cells of the wasp are of as regular construction as those of the honey-bee at the sides; but at the bottom, which is the part of the honey-comb that has more particularly engaged the attention of mathematicians, there is no evidence of any geometrical instinct.

The nature of the influence under which the cells are constructed with such wonderful accuracy is a problem of the highest interest. It has generally been discussed with particular reference to the cells of the honey-bee. But wasps' cells are on some accounts to be preferred for the examination of this question. The nature of the materials of which they are made excludes the hypothesis that the cells owe their hexagonal form in any degree to the crystalline cleavage of the wax. And the evident mode of construction of the paper cell shows that the wax cell need not have been built solid and hollowed out subsequently to prove so exactly regular, but may have been-as indeed it is-raised. at once in its accurate outlines.

There are two theories on this subject. One theory refers the hexagonal form of the cells to objective influences, to a physical necessity, comparing the formal results of the conjoined labours of many

insects to those of an uniform lateral pressure, under which cylinders of any soft substance take an hexagonal form. This comparison, however, is fanciful, and is not quite supported by facts. For some wasps make their combs-very small ones it is true-entirely of cylindrical cells, the lateral pressure notwithstanding. The other theory refers the form of the cells to a subjective influence, an instinctive impulse; and to this I must express my adhesion. It is not a fatal objection to this theory that wasps, where they are free to build in any form, as, for instance, at the edges of the comb, build cells of less regular shapes; for the hexagonal principle may still be traced in these irregular cells, though the result be obscured somewhat by the stronger impulse, if I may be allowed to say so, of not taking unnecessary trouble where nothing is to be gained by such scrupulous accuracy. So far, indeed, from these irregularly hexagonal cells disproving the instinct theory, their occurrence is rather an argument for its correctness. For we cannot explain why such cells should take an hexagonal form at all, however rudely expressed, except on the assumption that they are built under an instinctive impulse.*

Each building pellet is applied with great exactness to three sides, two of one cell, and one of an adjoining cell. In this way the cell-walls are interlaced with one another; and much greater strength is given to the whole comb than if the three outer sides of each cell were built up independently of the three

* This subject is discussed by Mr. Wood, and illustrated in his usual happy manner, both as regards bees and wasps, in 'Homes without Hands,' pp. 432 and 570.