sion of processes co-ordinated for a given result; a peach is not directly developed as such from its elements; the seed would, a priori*, give no idea of the tree, nor the tree of the flower, nor the fertilised germ of that flower of the pulpy fruit in which the seed is buried. It is eminently characteristic of the Creative wisdom, this far-seeing and provision of an ultimate result, through the successive operations of a co-ordinate series of seemingly very different conditions. The further man discerns, in a series of conditions, their co-ordination to produce a given result, the nearer does his wisdom approach though the distance be still immeasurable—to the Divine wisdom. One philanthropist builds a fever-hospital, another drains a town. One crime-preventer trains the boy, another hangs the man. One statesman would raise money by augmenting a duty, or by a direct tax; and finds the revenue not increased in the expected ratio. Another diminishes a tax, or abolishes a duty, and through the foreseen consequences the revenue is improved. Every practical application of the discoveries of science, as of the political economist, tends to the promotion of the public weal.

The steam-engine, in its manifold applications, the crimedecreasing gas-lamp, the lightning conductor, the electric telegraph, the law of storms and rules for the mariner's guidance in them, the power of rendering surgical operations painless, the measures for preserving public health and for preventing or mitigating epidemics-such are among the more important practical results of pure scientific research with which mankind have been blessed and states enriched. They are evidence unmistakeable of the close affinity between the aims and tendencies of science and those of true state policy. Owen.

* A priori, mode of reasoning from cause to effect, independently of actual experience. Its opposite-a posteriori- concerns itself with proofs based on antecedent knowledge.

NATURAL HISTORY.

STINGS.

have been stung

PROBABLY at some period of your life you by a bee or wasp. I shall take it for granted that you have, and that having tested the potency of these warlike insects' weapons with one sense, you have a curiosity to examine them with another. The microscope shall aid your vision to investigate the morbific implement. This is the sting of the honey-bee, which I have but this moment extracted. It consists of a dark-brown horny sheath, bulbous at the base, but suddenly diminishing, and then tapering to a fine point. This sheath is split entirely along the inferior edge, and by pressure with a needle I have been enabled to project the two lancets, which commonly lie within the sheath. These are two slender filaments of the like brown horny substance, of which the centre is tubular, and carries a fluid in which bubbles are visible. The extremity of each displays a beautiful mechanism, for it is thinned away into two thin blade-edges, of which one remains keen and knifelike, while the opposite edge is cut into several saw-teeth pointing backwards. The lancets do not appear to be united with the sheath in any part, but simply to lie in its groove; their basal portions pass out into the body behind the sheath, where you see a number of muscle-bands crowded around them: these, acting in various directions, and being inserted into the lancets at various points, exercise a complete control over their movements, projecting or retracting them at their will. But each lancet has a singular projection from its back, which appears to act in some way as a guide to its motion, probably preventing it from slipping aside when darted forth, for the bulbous part

of the sheath in which these projections work seems formed expressly to receive them.

Thus we see an apparatus beautifully contrived to enter the flesh of an enemy; the two spears finely pointed, sharpedged, and saw-toothed, adapted for piercing, cutting, and tearing; the reverse direction of the teeth gives the weapon a hold in the flesh, and prevents it from being readily drawn out. Here is an elaborate store of power for the jactation of the javelins in the numerous muscle-bands; here is a provision made for the precision of the impulse; and, finally, here is a polished sheath for the reception of the weapons, and their preservation when not in actual

use.

All this is perfect; but something still was wanting to render the weapons effective, and that something your experience has proved to be supplied.

The mere intromission of these points, incomparably finer and sharper than the finest needle that was ever polished in a Sheffield workshop, would produce no result appreciable to our feelings, and most surely would not be followed by the distressing agony attendant on the sting of a bee. We must look for something more than we have seen.

We need not be long in finding it. For here, at the base of the sheath, into which it enters by a narrow neck, lies a transparent pear-shaped bag, its surface covered all over, but especially towards the neck, with small glands set transversely. It is rounded behind, where it is entered by a very long and slender membranous tube, which, after many turus and windings, gradually thickening and becoming more evidently glandular, terminates in a blind end.

This is the apparatus for preparing and ejecting a powerful poison. The glandular end of the slender tube is the secreting organ: here the venom is prepared. The remainder of the tube is a duct for conveying it to the bag, a reservoir in which it is stored for the moment of use. By means of the neck it is thrown into the groove at the moment the sting is projected, the same muscles, probably,

that dart forward the weapon compressing the poison-bag, and causing it to pour forth its contents into the groove, whence it passes on between the two spears into the wound which they have made.

When this apparatus is not accompanied by a poisonreservoir, it is ancillary to the deposition of the eggs, and is hence called an ovipositor, and this is illustrated in the common gall-fly.

"There can be no doubt that the mother gall-fly makes a hole in the plant for the purpose of depositing her eggs. She is furnished with an admirable ovipositor for that express purpose, and Swammerdam actually saw a gall-fly thus depositing her eggs, and we have recently witnessed the same in several instances. In some of these insects the ovipositor is conspicuously long, even when the insect is at rest; but in others not above a line or two of it is visible till the belly of the insect be gently pressed. When this is done to the fly that produces the currant-gall of the oak, the ovipositor may be seen issuing from a sheath in form of a small curved needle, of a chestnut-brown color, and of a horny substance, and three times as long as it first appeared.

"What is most remarkable in this ovipositor is, that it is much longer than the whole body of the insect, in whose body it is lodged in a sheath; and, from its horny nature, it cannot be either shortened or lengthened. It is on this account that it is bent into the same curve as the body of the insect. The mechanism by which this is effected is similar to that of the tongue of the woodpeckers; which, though rather short, can be darted out far beyond the beak by means of a forked bone at the root of the tongue, which is thin and rolled up like the spring of a watch. The base of the ovipositor of the gall-fly is, in a similar way, placed near the anus, runs along the curvature of the back, makes a turn at the breast, and then, following the curve of the belly, appears again near where it originates.

"With this instrument the mother gall-fly pierces the

R

part of a plant which she selects; and, according to our older naturalists, 'ejects into the cavity a drop of her corroding liquor, and immediately lays an egg or more there, the circulation of the sap being thus interrupted and thrown by the poison into a fermentation that burns the contiguous parts and changes the natural color. The sap, turned from its proper channel, extravasates and flows round the eggs, while its surface is dried by the external air, and hardens into a vaulted form.'' Gosse and Rennie.

CIRCULATION OF THE BLOOD IN A FROG.

I HAVE here a living frog. You perceive that the web which connects the toes is exceedingly thin and translucent, yet arteries and veins meander through its delicate tissues, which are then clothed on both surfaces with the common skin. But you ask how we can induce the frog to be so polite as to hold his paw up, and keep it steady for our scientific investigation. We will manage that without difficulty.

Most microscopes are furnished (among their accessory apparatus) with what is called a frog-plate, provided for this very demonstration. Here is mine. It is a thin plate of brass, two inches and a half broad and seven long, with a number of small holes pierced through it along the margins, and a large orifice near one end, which is covered with a plate of glass. This is to be froggy's bed during the operation, for we must make him as comfortable as circumstances will admit. Well, then, we take this strip of linen, damp it, and proceed to wrap up our unconscious subject. When we have passed two or three folds round him, we pass a tape round the whole, with just sufficient tightness to keep him from struggling. One hind-leg must project from the linen, and we now pass a needle of thread twice or thrice through the drapery and round the small of this free leg, so as to prevent him from retracting it.