new world of living beings, sufficiently resembling that in which we are ourselves destined to exist, to prove that it is the work of the very same Creator; yet, as we shall presently see, so different in many respects, besides its extreme minuteness, as to show, still more distinctly, the inexhaustible resources of the Divine Mind, in the endless variety of created existences. The most minute of those animalcules which have been studied and delineated, are the infusory, that is, those which are found in liquids; and to these we shall at present confine ourselves. They have been divided into two classes, those with external organs, and those in which such organs are wanting. Of the former, seven genera have been enumerated, and 254 species; of the latter, ten genera, and 123 species. These, it is not to be doubted, form a very small part of the actual existences, many of which are so minute, that they elude the action of the most powerful magnifiers,-as may be safely inferred from the fact, that new species, descending in minuteness, have constantly been discovered, in proportion as the power of the microscope has been increased.

The wonderful diversity of shape in these animalcules, has been thus described :-"Let one suppose himself transported to a region, where the appearance, figure, and motion, of every animal is unknown, and he will form some idea of the variety presented by a drop of an infusion, observed by means of the microscope. One animalcule is a long slender line; another is coiled up like an eel or a serpent; some are circular, elliptical, or globular; others a triangle or a cylinder; some resemble thin flat plates; and some may be compared to a number of articulated reeds; one is like a funnel, and another like a bell; and the structure of many cannot be compared to any object familiar to our senses. Certain animalcula, such as the Proteus diffluens, can change their figure at pleasure, being sometimes extended to immoderate length, and then contracted to a point; one moment they are inflated into a sphere, the next completely

flaccid, and then various eminences will project from the surface, altering them apparently into animals entirely different. Neither is the peculiar motion of animalcula less remarkable; in several species, it consists of incessant gyration on the head as a centre, or around a particular point, as if one of the foci of an ellipse; the progression of others is by means of leaps or undulations; some swim with the velocity of an arrow, and the eye can scarcely follow them; some drag their unwieldy bodies along with painful exertion; and others, again, seem to persist in perpetual rest."

In turning to the organs of these microscopic animals, we shall find equal subject for admiration. Some take their food by absorption, being destitute of a mouth; others have a mouth, and several stomachs, amounting, sometimes, to the remarkable number of forty or fifty; some are without eyes, others have several; some have mandibles, and others have processes resembling legs; while many have their mouths fringed with ray-like bristles. In many the internal structure is quite peculiar, in others it bears a remarkable analogy to that of higher species. Each class has its own particular food; some live on vegetable substances, others are predaceous, and others again seem to derive their nourishment entirely from absorbing the liquid in which they exist.

Let it not be forgotten, that all this minute organization, and these various appetites, habits, and motions, belong to existences too minute, in most instances, to be even discernible by the human eye; and we shall find it almost as difficult to stretch our imagination downward, to the infinitely little among created objects, as it was to rise to the contemplation of the infinitely great. To the minute subdivision of matter, there seems to be no conceivable bounds. This is not very hard to admit; but, to be compelled to believe that the most minute particle which our fancy can frame is an organized and

Edinburgh Encyclopedia article Animalcule, written by Dalzell, the Translator of Spallanzani.

living being,—that it has a complex system of members, each of which is most skilfully fitted for its peculiar functions,—that the processes of digestion, of nutrition, and of reproduction, are carried on in these invisible particles with equal perfection as in our own bodies,—that they have instincts, and habits, and powers of choice and of enjoyment,—all this appears so amazing, that the mind can scarcely yield itself to the belief. And, yet, why should it not? All magnitude and quantity are relative. We judge of them merely by the measure of our own experience; and, if we could but sufficiently disengage our minds to take an abstract view, we would perceive that there is, in reality, nothing more incredible in the subdivision and organization of what appears to us infinitely minute, than in the construction of the animals with which our senses are conversant.

Yet what an amazing view is opened up to us, of the Creator, and his infinitely diversified works! The exclamation of Pliny, with regard to insects, may, with peculiar emphasis, be applied to the wonders of the microscopic world :—In his tam parvis, atque tam nullis, quæ ratio, quanta vis, quam inextricabilis perfectio! It may be difficult to determine to what extent, or even in what manner, these innumerable myriads of invisible beings produce a salutary effect on the visible world; but we may be sure that it was not without a benevolent object that they were every where scattered over the world. Like the larvæ of certain insects, they probably act the important part of scavengers, in removing nuisances from the liquids in which they live, and preserving in them a healthy action. At all events, besides enjoying, as they doubtless do, a kind of happiness in themselves, they furnish food to animals of a somewhat higher species, while these, again, afford support to animals still higher in the scale, and so on, through all the gradations of animated beings,-one species preying upon another, and thus, by a mysterious arrangement, increasing the quantity of living creatures, by an increase of their means of subsist

ence. It is truly wonderful to observe the wise contrivances by which life is sustained, in all its forms. First, from the crude earth springs the vegetable by which food is elaborated for living creatures; and then follow the countless hosts of invisibles, which prey on these, or their infusions, and on one another; and then, rising through numerous grades, in a thousand different forms, and with continually varying faculties and habits, come the various orders of sentient beings, which fill and adorn the visible creation, deriving their food, like their microscopic fellow creatures, some directly from the vegetable kingdom, others from the bodies of animals which have died a natural death, and others again by the destruction of living creatures. Such is the law of existence, exhibiting the clearest evidence of wise contrivance, but yet marked, in this as well as in other particulars, with the peculiar character belonging to a world blighted with a

curse.

FIFTH WEEK-TUESDAY.

I. PLANTS AND ANIMALS COMPARED.

It is my intention now to devote some papers to the consideration of what has been called the hybernation of plants and animals; but, before entering on this highly interesting subject, I shall make a few cursory observations on some of the general characters in which vegetable and animal existences resemble each other, and of others in which they differ. Such an examination is not only curious in itself, and satisfactory, as illustrating the remarkable unity of design which exists in creation, but useful to our purpose, as forming a proper introduction to the various particulars which I shall afterward have to investigate.

The first and most important resemblance between

plants and animals is in their possessing what has been called a living principle. This constitutes the chief difference between organized and unorganized existences; and it is only while it exists in the former, that these exhibit the other qualities by which they are distinguished from brute matter. What this living principle is, it may be impossible to say; but that it is something which possesses distinct properties, and performs peculiar functions, the most ignorant are aware. An animal breathes, and moves, and feels, and performs certain actions for a time; this is animal life. It then ceases to show any of these properties; it lies motionless and insensible; it undergoes rapid decomposition, and is resolved into its original elements. This is death: And something analogous to this takes place in plants. The living principle appears, indeed, under a different and less perfect modification; but still it is there. Although vegetable existences have no voluntary motion, they yet possess certain vital functions; they select and secrete their food; they grow; they expand and flourish. This is vegetable life. After a time, these functions cease; they droop, decay, and are decomposed. Their life is fled.

Both in animals and vegetables, the principle of life is endowed, or at least connected, with a power of repairing injuries to a certain extent, so as to reproduce decayed or destroyed parts. In both, also, there exists a power of reproducing the species. Nor is the similarity less remarkable in regard to a property, the existence of which, in vegetables, was, till lately, but little known, I mean the circulation of a fluid through every part of the body. That the blood circulated through the veins of animals, was a fact which could never escape observation, although the principle on which this remarkable function depended, was but lately discovered; but it does not seem to have been suspected, till within these few years, that there was an analogous circulation through vegetable substances. That sap existed in plants, indeed, was