form a bond between the young of the republic, and their seniors, which, from the first moment of their final transformation, should connect them together by those strong and tender sympathies that subsist among benefactors and the benefited. Such arrangements among animals living in community are not rare. We may trace them, in a greater or less degree, through all those tribes which associate together for a common interest, beginning with man himself; and they very strangely indicate not only the forethought but the benevolence of Him who has instilled the social instinct, and caused it to be productive of enjoyment to so many orders of beings.

As soon as the insect is extricated, it is found, in by far the greater number of instances, extending not only to many species, but also to numerous orders, to be furnished with wings, and destined to find its way through the atmosphere. That little creature which had hitherto grovelled in the earth, and whose powers of locomotion were so limited, has now acquired a power by which it can readily transport itself to considerable distances from place to place, and obtain varied enjoyments, to which, in the earlier stages of its existence, it was altogether a stranger. To this new condition some very peculiar circumstances are necessary; among these buoyancy is one of the most obvious. We have already seen how this is provided for in birds.* Something similar, but corresponding to the peculiarities of their conformation, is found also in insects. It is by means of internal airvessels that the requisite degree of lightness is obtained. We may not be able to trace very distinctly the peculiar mechanism by which this is effected, by reason of the minuteness of the organs; but one of the most remarkable phenomena which distinctly mark its existence, is the expansion of the body and wings, on the extrusion of the perfect insect from its pupa case. A very striking exemplification of this occurs in the transformation

Spring."-Relation of the Bodies of Birds to External Nature, p. 274.

of the ant-lion, whose singular instincts are so well known. When this creature has emerged from its cocoon, it only requires to expand its wings and body, in order to complete its transformation; but this is a process calculated to excite our highest admiration; for, though it is not at first more than half an inch in length, it almost instantaneously stretches out to an inch and a quarter, while its wings, which did not exceed the sixth part of an inch, acquire an immediate expansion of three inches.*

A similar increase of size is observable, to a greater or less degree, in all the insect tribes which rise into the air; and it is doubtless effected by the introduction of air into the receptacles of the body. They thus become exceedingly light, in proportion to their bulk, and their power of floating in the atmosphere is greatly facilitated.

The expansion of the wings is also a subject worthy of observation. They are folded up, and sometimes doubled, in a very compressed state, while they remain in the chrysalis; but presently assume extraordinary dimensions, when exposed to the air. In the instance of the silkx-worm moth," they expand so rapidly that it is not easy to trace their unfolding; for, in the space of a few minutes, they increase in dimensions about four-fold. Their spots and colours, at the same time, previously so small as to be scarcely discernible, become proportionally extended; so that, what, but a few minutes before, appeared as a number of confused and indistinct spots, acquires many varied beauties of colour and form.”+

The motions of insects, indicating enjoyment, are very remarkable; and, from this circumstance, Paley, with his usual felicity, has drawn an argument for the benevolence of the Deity. The following extract from a very interesting account, by Reaumur, of the appearance of

* The lace-winged fly exhibits a still more remarkable and not less sudden growth. The pupa of this insect is not bigger than a small pea, while the fiy is nearly an inch in length, and the expanse of the wings about two inches.

+ Insect Transformations, p. 341.

VOL. III.

M

the day-flies, or ephemerae, on the banks of the Seine, illustrates the same truth. These insects are destined to live but a few hours, yet their brief time seems full of exstatic enjoyment. "The countless numbers of ephemeræ," says he, "which swarmed over the water, can neither be conceived nor expressed. When snow falls thickest, and in the largest flakes, the air is never so completely full of them as that which we witnessed filled with ephemera." It was evening; and Reaumur procured a torch which at once attracted them, and advantageously showed their gyrations. "The light of the torch gave origin to a spectacle which enchanted every one who beheld it, and was altogether different from a meteorological shower; even the most stupid and unobserving of my domestics were never satisfied with gazing at it. No armillary sphere was ever formed of so many circular zones, in every possible direction, having the light for their common centre. Their number seemed to be infinite, crossing each other in all directions, and in every imaginable degree and inclination, all of which were more or less oblique. Each of these zones was composed of an unbroken string of ephemeræ, which followed each other close in the same line, as if they had been tied together head and tail, resembling a piece of silver ribbon, deeply indented on its edges, and consisting of equal triangles placed end to end; so that the angles of those that followed, were supported by the base of those which preceded, the whole moving round with incredible velocity. This spectacle was caused by the wings of the insects, which alone could be distinguished. Each of these flies, after having described one or two orbits, fell to the earth, or into the water, though not in consequence of having been burned.": Nothing could more distinctly indicate extreme delight, which seemed to end only when the joyous beings ceased to feel.

* Reaumur, Mem. vol. vi. p. 485.

SIXTH WEEK-THURSDAY.

THE BUILDING SPIDER.

PASSING Over various tribes, both of sea and land animals, which succeed each other in an ascending scale, such as the various orders of shell-fish, of worms, of leeches, of crustaceans, &c., I shall come at once to the varied and interesting families of insects, of which the first I shall select for consideration is the spider. There are several species of this remarkable insect, most of them possessing some peculiarity of habits, or organization, by which they are distinguished; but among these there is none either more singular, or better calculated to exhibit a proof of Designing Wisdom, in its instincts, than that class which has acquired the appropriate name of the trap-door or building spider. I shall follow the account of the celebrated M. V. Audoin, as abridged by Mr Kirby in his Bridgewater Treatise.*

Some species of spiders, M. Audoin remarks, are gifted with a particular talent for building: they hollow out dens; they bore galleries; they elevate vaults; they build, as it were, subterranean bridges; they construct, also, entrances to their habitations, and adapt doors to them, which want nothing but bolts; for, without any exaggeration, they work upon a hinge, and are fitted to a frame.

The interior of their habitation, he continues, is not less remarkable for the extreme neatness which reigns there; whatever be the humidity of the soil in which they are constructed, water never penetrates them; the walls are nicely covered with tapestry of silk, having usually the lustre of satin, and almost always of a dazzling whiteness. He mentions only four species of the genus as at present known;-one which was found in

Vol. ii. pp. 287-293.

the island of Naxas; another in Jamaica; a third in Montpellier; and a fourth, that which is the subject of his Memoir, in Corsica; to which I may add a fifth species, found frequently by Mr Bennett, in different parts of New South Wales.

The habitations of the species in question are found in an argillaceous kind of red earth, in which they bore tubes about three inches in depth, and ten lines in width. The walls of these tubes are not left just as they are bored, but they are covered with a kind of mortar, sufficiently solid to be easily separated from the mass which surrounds it. If the tube is divided longitudinally, besides this rough-cast, it appears to be covered with a coat of fine mortar, which is as smooth and regular as if a trowel had been passed over it. This coat is very thin, and soft to the touch. But, before this adroit labourer lays it, she covers the coarser earthy plaster-work with some coarse web, upon which she glues her silken tapestry.

All this shows, that she is directed in her work by a wise Master; but the door that closes her apartment is still more remarkable in its structure. If her well was always left open, she would be subject to the intrusion of guests, that would not, at all times, be welcome or safe. Providence, therefore, has instructed her to fabricate a very secure trap-door, which closes the mouth of it. To judge of this door by its outward appearance, we should think it was formed of a mass of earth coarsely worked, and covered internally by a solid web; which would appear sufficiently wonderful for an animal that seems to have no special organ for constructing it; but, if it is divided vertically, it will be found a much more complicated fabric than its outward aspect indicates, for it is formed of more than thirty layers of earth and web, emboxed, as it were, in each other, like a set of weights for small scales.

If these layers of web are examined, it will be seen that they all terminate in the hinge; so that the greater