movements to allow me to identify them before, or to perceive anything else than their swift motion and oval form ; but this attraction, causing them to become still, allowed me to perceive their singular and beautiful structure. Each consists of an oval vase open at the top, the margin of which is cut into a number of little points; the sides are marked by a series of ribs, which run down longitudinally, and are crossed by other transverse ones ; the rounded bottom is furnished with three short points, so that the whole reminded me of a barrel with its staves and hoops, set on a three-legged stool. Within the body, which is colourless, are seen small dark spots which are probably the stomach-vacuoles. Thus I identified these little barrels with Coleps hirtus of Ehrenberg, but I found no record of their carnivorous propensities. One after another whirled into the field, and after a few gyrations became stationary at the head of the half-born Euchlanis, just as I have seen vultures gather one by one to a carcass. Very soon there were a dozen or fifteen of them, some of which were ever shifting their places, and some were playing around, or revolving on their longitudinal axes. I found that their object really was to prey on the soft parts of the creature just excluded from the egg; for, by carefully watching one, I distinctly perceived particles of the flesh fly off, as it were, and* disappear in the body of the Coleps. The appearance was that of steel filings drawn to a magnet, for the mouth of the Coleps was not in actual contact with the flesh; and therefore, I suppose, the surface having been in some way ruptured (which I could see it was), the loose gelatinous atoms were sucked off by a strong ciliary current. They did not attack any other part, and after having continued their murderous occupation about ten minutes, they one by one departed. The ciliary motion of the Euchlanis ceased immediately after it was first attacked, and I suppose it was soon killed, for it did not increase in size in the least afterwards. When the Colepes left it, a great portion, perhaps a third, of the excluded parts was devoured.

As soon as the depredators were gone, or even before, others more diminutive, but more numerous, were ready to take their place. The drop of water under review had been found amazingly full of a small oval Jlonas, perfectly transparent, of an oval form, with some granules visible in the interior. They were about -joVo °^ an ^nc^ ^n length. They filled the whole field, gliding about very nimbly, but so close as but just to allow space for motion, and that in several strata. By the morning these were collected in masses, which to the naked eye looked like little undefined white clouds, but which under the microscope showed the Monads in incalculable multitudes, but for the most part in still repose. Some were seen moving to and fro, however, and, in the course of the day, most of them became again active. As soon as the Colepes had forsaken their prey, the Monads began to gather round it, cleaving to the same parts, and apparently imbibing the juices, for the extruded parts still slowly decreased, until at length these were reduced to about one-third of their original dimensions.

A close examination of these latter when they had settled to rest showed me that they were of the species Chilomonas iKiramozcium. There is an indentation on one side of the front where the mouth is situated: here there is a ciliary action ; the projecting part, called the lip, is said to be furnished with two slender flexible proboscides, but my power was not sufficient to discern any trace of these. A sort of a ridge, or keel, runs down the length of the body, perceptible by a slight line ; numbers of stomach-cells also are perceptible. The motion of these lip-monads was not very rapid when unexcited • it is performed by a sort of lateral half-roll, the two sides alternately being turned up, like a boat broadside to a swell, and the line of progression is undulating. 2 D And now, having pretty well exhausted the contents of this live-box, let us try a dip from this other phial from another locality, equally productive, if I am not mistaken. Yes; for, to begin, the stalks of Nitella here are fringed with populous colonies of the most attractive of all the Infusoria, the beautiful Vorticellce. The species is not the common bell-shaped one, but the smaller with pursed mouth, the little V. microstoma.

Look at this active group, consisting of a dozen or so of glassy vases, shaped something like pears, or elegant

YOETICELX^:.

antique urns, elevated on the extremities of long and very slender stalks, as slender as threads, and about six times as long as the vases. The stalks grow from the midst of the floccose rubbish attached to the plant, and diverge as they ascend, thus carrying their lovely bells clear of one another.

Each vase is elegantly ventricose, or swollen, in the

middle, terminating below in a kind of nipple to which the stalk is attached, and above in a short wide neck with a thickened rim. This last is highly sensitive and contractile ; its inner edge is set round with a circle of vibratile cilia, which, when in full play, produce a pair of small circular whirlpools over two opposite points of the brim. The cilia themselves cannot be distinguished, but their optical expression is curious. At the two opposite points of the circular margin, as seen in perspective when slightly inclined towards the observer, viz., at those points where the cilia, from their position with regard to the eye, would be crowded together, there are seen two dark dashes, representing, doubtless, two ciliary waves, but which have all the appearance of tangible objects, sometimes withdrawn, sometimes protruded, and often vibrated with a rapid snatching movement.

These vases are of the usual appearance in Infusoria. Their substance is the clear transparent colourless sarcode, but it contains within it more or less of the cloudy nebulous matter which we have been lately familiar with. There are several globular vesicles or vacuoles, some ready to imbibe colour from pigment, and others already occupied with brown food ; while in each case we see, near the centre of the vase, a longish body of clear granular texture, which is called the nucleus, and which seems to play an essential part in the vital economy of the animal.

The movements of a group such as that we are looking at are very sprightly and pleasing. The vases turned in all directions, some presenting their mouths, some their sides, some their bases, to the eye ; inclined at various angles from the perpendicular, and bending in diverse degrees upon the extremity of their stalks; swaying slowly and gracefully to and fro, as driven hither and thither by the ciliary currents; and, above all, ever flying up and down within the length of their radius, as a bird when confined by a string ;— all these circumstances 2 d 2 impart a charm to this elegant animalcule, which enables us to look long at it without weariness.

This last movement is peculiar, and worthy of a moment's closer examination. The stalk, when extended to the utmost, is an elastic glassy thread, nearly straight, like a wire, but never so absolutely straight as not to show slight undulations. The stalk, when thus drawn tight, is highly sensitive to vibrations in the surrounding medium ; and as in the circumstances in which we observe the animals, such vibrations must be every instant communicated to the vessel in which they are confined, the stalks are no sooner fully extended than they contract with alarm. This depends on a contractile cord which passes throughout the entire length of the stalk, and which is distinctly visible in the larger species as a narrow band. We can scarcely err in considering this ribbon as a rudimentary form of muscle, though we do not recognise in it some of the characteristic conditions which we are accustomed to see in it in higher animals.

The contraction of the muscle is very sudden, energetic, and complete. With a rapidity which the eye cannot follow, the vase is brought down almost to the very base of the stalk. Then it slowly rises again ; and now we see, what we could not discern in the act of contraction itself, that in that act the stalk was thrown into an elegant spiral of many turns, which at the utmost point of contraction were packed close on each other, but which in the extending act gradually separate, and at length straighten their curves.

In any stage of the extension, the sudden contact of the vase with any floating or fixed object apparently causes alarm, and induces the vigorous contraction; but vibrations, even when so violent as those produced by tapping the stage of the microscope with the finger-nail, have no effect unless the stalk be tense, its own power of vibration being then only developed, just as a cord becomes musical in proportion to its tension.

is not until we view these creatures with a good microscope that we acquire an adequate idea of their beauty : for myself, at least, it was so. I had seen engravings of many of the invisible animalcules, and had read technical descriptions ; but of their brilliant transparency, their sudden and sprightly motions, their general elegance and delicacy, and the apparent intelligence with which they are endowed, neither books nor engravings had given me any conception.

Some of the individuals under our present examination are exhibiting phenomena of no less interest than their form and motions. Some of the stalks are terminated by two vases instead of one, which appear to spring from a common point. These, however, are the result of the spontaneous splitting of one; and in other examples you may see the process in different stages ; or, if your patience endure a couple of hours' watching, you may trace the whole phenomena, as I have done, from the moment when it first becomes perceptible, to its completion in the freedom of one of the newly-formed animalcules.

For instance, you perceive that one of the bells instead of being vase-shaped has assumed a globular form. By keeping your eye on this for only a few moments, you detect a depression forming in the midst of its front outline, which momentarily deepens, until it is manifestly a cleft. The division proceeds downwards, the two halves healing simultaneously, so that they are at all times perfectly smooth and rounded; at length two vases appear, side by side, where a few minutes before there had been but one.

One of these is destined to be ultimately thrown off, while the other retains sole possession of the stalk. You soon see which it is that is going to emigrate: for, though the two are alike in size, the roving one early closes the mouth of the vase, becoming smooth and globular there, never to open again. The cilia, now therefore become useless, disappear by absorption ; but meanwhile a new circle of these organs is developed around the basal extremity of the vase, and these, every instant becoming more vigorous in their motions, sway the little globe about on its point of attachment. At length the connexion yields, breaks, and the animalcule shoots away, rowed by its hundred oars, to find a new abode, and to found a new colonv.

Here and there you see shooting through the group, with a rapid gliding movement, an oblong clear body. This is one of the vases, formed by self-division, and exercising its newly-found power of locomotion. It is giddily roving hither and thither, until the instinct of wandering ceases, when it will soberly settle down, affix itself by the point which was formerly its mouth, whence a new stalk will gradually grow, and opening a new mouth in the midst of the new crown of cilia,

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