In the foot of the fly under our own observation, you may see how well the joints of the tarsus are covered with hairs, or rather stiff pointed spines, of various dimensions and distances apart, and hence how suitable these are for acting the part of combs to cleanse the palms. But these last are the organs that most claim and deserve our examination. In the specimen of the little Musca that I have imprisoned, the last tarsal joint is terminated by two strong divergent hooks which are themselves well, clothed with spines, and by two membranous flaps or palms beneath them. These are nearly oval in outline, though in some species they are nearly square, or triangular, and in some of a very irregular shape. They are thin, membranous, and transparent, and when a strong light is reflected through them, we see their structure under this power of GOO diameters very distinctly.

The inferior surface of the palm, on which we are now looking, is divided into a vast number of lozenge-shaped areas, which appear to be scales overlapping each other, or they may be divided merely by depressed lines. From, the centre of each area proceeds a very slender, soft, and. flexible pellucid filament, which reaches downwards to the surface on which the fly is walking, and is there slightly hooked, and enlarged into a minute fleshy bulb. Those from the areas near and at the margins of the palms more and more arch outwards, so that the space covered by the bulbs of the filaments is considerably greater than that of the palm itself. * " In trod, to Entom.," 7th Ed., 458. i 2 Now it is evident that the bulbous extremities of these soft filaments are the organs of adhesion. We notice how they drag and hold, as the fly draws its foot from its place ; and it seems almost certain that the adhesion is effected by means of a glutinous secretion poured out in minute quantities from these fleshy tips. When the foot is suddenly removed, we may often see a number of tiny particles of fluid left on the glass where the filaments had been in contact with it : but I do not build conclusively on this appearance, because the fly, having been confined for some quarter of an hour in this nearly tight glass cell, has doubtless exhaled some moisture, which has condensed on the glass ; and the specks we see may possibly be due to the filaments of the palms having become wet by repeatedly brushing the moist surface. Mr. Hepworth, however, asserts that a fluid is poured out from these filaments, and is deposited on the glass, when the fly is vigorous, with great regularity. He says that " when in a partially dormant state, the insect does not appear to be able to give out this secretion, though it can still attach itself : indeed, this fluid is not essential for that purpose." * It is asserted that the speckled pattern of fluid left on the glass by the fly's footsteps remains (if breathed on) when

FOOT OF FLT.

the moisture is evaporated ; and hence it is presumed to be of an oily nature.

In some Beetles the joints of the foot are furnished with * " Micros. Journal" for April, 1854.

insects: their feet. similar appendages. I shall now show you the fore-foot of a well-known insect, called by children the Bloody-nose Beetle (Timarcha tenebricosa), a heavy-bodied fellow, of a blue-black colour, abundant in spring and summer on hedge-banks. You have doubtless often observed it, and have been amused, perhaps, at seeing the drop of clear scarlet fluid which exudes from its mouth when touched.

The feet in this species are broad and well developed. You may see with the naked eye, on turning it up, that its dilated joints are covered on the under surface with a velvety cushion of a rusty-brown colour; and here, under a low power of the microscope with the Lieberkiihn, you can determine the nature of the velvet.

The foot, or tarsus, as it is technically called, is composed of four very distinct pieces ; of which the first is semicircular, the second crescent-shaped, the third heartshaped, and the fourth nearly oval. The last is rounded on all sides, has no cushioned sole, and carries two stout hooks. The first three are flat, or even hollowed beneath into soles, something like the hoof of a horse ; and the whole interior bristles with close-set minute points, the tips of which terminate at the same level, and form a velvety surface. Now, these points are the whitish bulbous extremities exactly answerable to those on the palms of the fly, and doubtless they answer the very same purpose. Only here they are set in far closer array, and are a hundred times more numerous; whence we may reasonably presume a higher power of adhesion to be possessed by the beetle. The structure is best seen in the male, which may be distinguished by its smaller dimensions, and by its broader feet.

A still better example of a sucking foot is this of the Dyticus marginalis. It is the great flat oval beetle, which i-< fond of coming up to the surface of ponds, and hanging there by the tail with its pair of hind legs stuck out on each side at right angles ; the redoubtable monster which little boys who bathe hold in such salutary awe under the name of Toe-biter. We have turned the tables upon the warrior, and have bitten his toe—off, and here it is. This is the tarsus of one of the fore limbs.

The peculiarity that first strikes us is that the first three joints are as it were fused into one, and spread out so as to make a large roundish plate. The under surface of this broad plate is covered with a remarkable array of

FOOT OF WATER-BEETLE.

Large Sucker, bb. Two smaller suckars. 2. Oue of the last more

c. Small crowded suckers. enlarged. sucking-disks, of which one is very large, occupying about a fourth part of the whole area. It is circular, and its face is strongly marked with numerous fibres radiating from the centre. jSTear this you perceive two others of similar form and structure, but not more than one-tenth

insects: their feet. part of its size ; one of these, moreover, is smaller than the other. Indeed, the size and number of these organs differ in different individuals of the same species.

The greater number of the suckers are comparatively minute ; but they are proportionally multitudinous and crowded. Each consists of a club-shaped shaft, with a circular disk of radiating fibres attached to its end. The whole apparatus constitutes a very effective instrument of adhesion.

There is a somewhat similar dilatation of the first joints of the tarsus, but for a very different object, in the Honeybee; and it is particularly worthy to be observed, not only for the interesting part which it plays in the economy of the insect, but for the example it affords us of the adaptation of one and the same organ to widely different uses, by a slight modification of its structure.

It is the hind foot of the Bee that w Te are now to examine. The first joint is, as you see, enlarged into a wide, long, and somewhat ovate form, constituting a flattish plate, slightly convex on both surfaces. The upper face presents nothing remarkable ; but the under side is set with about nine stiff combs, the teeth of which are horny straight spines, set in close array, and arranged in transverse rows across the joint, nearly on a level with its plane, but a little projecting, and so ordered that the tips of one comb slightly overlap the bases of the next. We see them in this example very distinct, because their colour, a clear reddish-brown, contrasts with a multitude of tiny globules of a pale yellow hue, like minute eggs, which are entangled in the combs.

Now these globules serve to illustrate the object of this apparatus. They are grains of pollen ; the dust that is discharged from the anthers of flowers, which, being kneaded up with honey, forms the food of the maggot of the Bee, and is, therefore, collected with great perseverance by the industrious insect : and the way in which it collects it is, by raking or combing it from the anthers, by means of these effective instruments on its hind feet.

You see that in this specimen the combs are loaded with the grains, which lie thickly in the furrows between one comb and another. But how do they discharge their gatherings 1 Do they return to the hive as soon as they have accumulated a quantity such as this, which one would suppose they could gather in two or three scrapes of the foot 1 No ; they carry a pair of panniers, or collecting baskets, which they gradually fill from the combs, and then return to deposit the results of their collecting

One of these baskets I can show you; and, indeed, it would be unpardonable to overlook it, for it is the com panion structure to the former. I make the stage forceps to revolve on its axis, and thus bring into focus the joint (tibia) immediately above that of the combs, and so that we shall look at its opposite surface: that is, the outer. We notice at once two or three peculiarities, which distinguish the joint in this instance from other parts of the same limb, and from the corresponding part in the same limb of other insects.

First, the surface is decidedly concave, whereas it is ordinarily convex. Secondly, this concave surface is smooth and polished (except that it is covered with a minute network of crossed lines), not a single hair, even the most minute, can be discerned in any part; whereas the corresponding surface of the next joints, both above and below, is studded with fine hairs, as is the exterior of insects generally. Thirdly, the edges of this hollowed basin are beset with long, slender, acute spines, which follow the same curve as the bottom and sides, expanding widely, and arching upward.

Here, then, we have a capital collecting basket. Its concavity of course fits it to contain the pollen. Then its freedom from hairs is important: hairs would be out of place in the concavity. Thirdly, the marginal spines insects: their feet. greatly increase the capacity of the vessel to receive the load, on the principle of the sloping stakes which thefarmer plants along the sides of his waggon when he is going to carry a load of hay or corn.

But, you ask, how can the Bee manage to transfer the pollen from the combs to the basket 1 Can she bend up the tarsus to the tibia 1 or, if she could, surely she could reach only the inner, not the outer surface of the latter. How is this managed 1

A very shrewd question. Truth to say, the basket you have been looking at never received a single grain from the combs of the joint below it. But the Bee has a pair of baskets and a pair of comb-joints. It is the right set of combs that fills the left basket, and vice versa. She can easily cross her hind-legs, and thus bring the tarsus of one into contact with the tibia of the other ; and if you will pay a moment's more attention to the matter, you will discover, in this beautiful series of contrivances, some further points of interest still. If you look at this living Bee, you notice that, from the position of the joints, when the insect would bring one hind-foot across to the other, the under surface of the tarsus would naturally scrape the edge of the opposite tibia in a direction from the basis of the combs towards their tips; and, further, that the edge of the tibia so scraped would be the hinder edge, as the leg is ordinarily carried in the act of walking.

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