membrane. Thus, also, Achnanthes is sea-froth; Anthachne, froth-flower; and Alcyonidium, the foam of the sea.

(32.) Many other similar examples might be given, for they continually occur, and in every language; although, when veiled in foreign tongues, or even when custom has given them an adventitious meaning, their original significations are not attended to. Thus, our own mildew is but a contraction of soft or mild dew, referring to the delicate texture of the minute plants of which mildew consists, and of which each spot is as it were a forest.

(33.) In the infancy of philosophy, such fanciful speculations and ideas, which we now think absurd, were common to all branches of science, and to other departments of natural history, as well as to the study of plants. Indeed, it is comparatively not long since an elaborate and learned disquisition was written, in order seriously to prove that the "flowing gossamer," the aerial spider's web, so common in autumnal mornings, is not scorched or frozen dew. The names alone are now happily all that remain to us of many of these crude doctrines, which we are too apt to denominate absurdities; not remembering that many of our received hypotheses, it is more than probable, are equally destitute of truth. They are but the clouds which attend the morning twilight of philosophy, and, as the sun of science rises, like the early dew, they pass away.

(34.) This class includes, in its several orders, sections, types, and genera, some of the most curious living structures which as yet are known. Protophytes, just emerging from lifelessness to life, and beings which, almost animals, still linger on the confines of the vegetable world.

(35.) Many of these microscopic creatures are so simple in their nature that their very simplicity renders them a doubt. Here, indeed, is the problem of which mention has been already made; for, so similar are many of the tribes of alge and of fungi, that it is not only sometimes indeterminable to which of these two great classes certain individuals should be referred, but whether, in truth, they are plants at all; for, strange as the statement does appear, many of them may be parts of other organic beings; and to some there has been attributed an half-animal existence.

(36.) Upon this point, however, modern research has thrown very considerable and very important light; and several of those ambiguous things called infusorial animalculæ, and named and

arranged as such in their systems by zoologists, and to which, by some, an equivocal or fortuitous generation had been most gratuitously attributed, it is more than probable are not of an animal but of a vegetable nature: and, besides this, very many of the moving corpuscules, which have often been mistaken for monads, and which hence were once most unphilosophically supposed to have sprung into existence without parental aid, are proved to be merely portions of dissolved or dissolving organic matter, loosened in its structure, and put into motion by physical powers, which had previously escaped detection by the observant eye of man. Allusion here, of course, is made to the curious phenomena described by Porrett under the name of Electrofiltration, and which Dutrochet has termed Endosmose and Exosmose, i. e. a flux-inwards and a flux-outwards, from the circumstance of two currents of different strengths being noticed to pass through organic membranes, when the fluids on either side are of different densities or in different electro-chemical states; and which will either fill or empty a fixed saccule, or put a moveable one in motion. This fact was first observed, by Dutrochet, to take place in the cellules of a small conferva, or moss-like production, which he detached from a fish's tail; and hence it comes properly to be considered here. Each portion of this moss (?) consisted of a filament and saccule, from which globules were expelled, and into and out of which the currents of fluids passed. He produced other similar globules, by putting pieces of flesh into the water, so that their formation was not connected with the living state of the fish. He saw these globules spread throughout the fluid, agitate themselves in divers directions for an instant, and then precipitate themselves to the bottom of the vessel.

(37.) But methinks I see some ultra-utilitarian smiling at the thought of a grave philosopher being thus engaged, for hours, in watching the motions of a corpuscule so minute as to be scarcely visible to the naked eye; and methinks I hear him ask "cui bono?" a question which any child may ask, but one that the wisest philosophers must often find it difficult to answer, although they may be far from admitting the pertinency of the interrogation. When such queries are proposed, as they often are, I love to meet them with Franklin's counter-question, "What's the use of a baby?" for no one will venture to inquire what is the use of a man.

The experiments which have led to this digression as yet are in

their infancy; but, even imperfect and crude as they confessedly at present are, they have already thrown much light on some very obscure parts of animal and vegetable physiology, and they promise to afford much more: they certainly disclose one of the most curious physical forces which have been discovered in modern times, and the just value of which we have not at present the means of estimating.

(38.) The same observations apply, and perhaps with still more truth, to that most curious discovery lately made by the celebrated Dr. Robert Brown, who has shown, by a most unexceptionable series of experiments, that locomotion, even when apparently independent of external forces, may and does exist among particles that are absolutely lifeless; nay, which have never been alive: so that, should not this phenomenon admit some more probable solution, it would seem that the long-established definition, which declares matter to be inert, may perhaps require a serious modification.

This apparently independent motion of the molecules of matter may appear to some to be a close approximation to the vital motions of plants, or the spontaneous movements of animals; and, indeed, the idea would seem more feasible than the belief of some German philosophers, that crystallization is an effect of vitality. The facts are simply these: that grains of pollen, particles of dead plants, some of which have been in herbaria for upwards of a century, nay, even fragments of powdered glass and stone, when diffused through water, and viewed with a good microscope, are seen to be in a constant state of motion; and this independent of any evaporation of, or currents in, the fluid; nay, still to maintain their restless activity when hermetically sealed between two plates of glass, so as to exclude, as far as possible, all external agitation, and are found, even under such circumstances, to continue their motions unremittingly during an indefinite period; nay, even after the lapse of months, (I believe we may now say years,) to be as full of motion as when first observed.

(39.) This discovery, as just now hinted, has been thought by some to militate against the ancient dogma, which enunciates the inertia of matter. It would ill become me to advance any speculations other than as mere hypotheses; and this the more especially as the discoverer himself, with that modesty which always attends true genius, does not even venture a speculation. I, therefore,

scarcely dare to suggest that it would be desirable to ascertain whether these movements may not be indicators of external motions, so slight as to be imperceptible to other means, rather than as inherent in the particles themselves. Just as many atmospheric changes are notorious with the water, that are utterly inappreciable with the mercurial barometer: and as the expansions of bodies by heat, and the vibrations of sound, are measurable by some instruments, which are imperceptible by others; so it would be desirable to ascertain whether the motions of these molecules do or do not depend upon vibrations, otherwise imperceptible, communicated by distant moving bodies to the surface of the earth, or to the matters on which they stand; or whether it is possible, as some of the movements seem very constant and similar, that they can evidence the motion of the earth itself, and thus afford the means of constructing a delicate kineometer.

(40.) But although many pseudo-animalculæ and (if we may be allowed the parallel word) vegetalculæ (?) are thus shewn not to be those wonders they were once supposed to be, and although locomotion is thus proved not to be absolutely diagnostic of life, still they are not the less wonderful now that they are regarded as what they truly are, lifeless corpuscules, put in motion by newly discovered and extraordinary laws, which their observation has been the first to reveal, than when they were considered paradoxes, and almost a reproach to natural science. And besides, even after their exclusion from the organic realm, there still remain many living beings, as simple in their structure and as curious in their functions as imagination can well conceive a vital organization to be, or ever to have been.

(41.) For example, the slimy matter often seen on rocks and stones, on hard gravel walks, and on damp walls and cellars, or on the glass of windows, garden pots, and so forth, and which is often so minute as to be lost to ordinary vision, consists of curious and most admirable vegetable structures. All the green pulverulent coating seen on old trees and palings is also found, by microscopic observations, to be composed of an infinite number of small plants, of an exceedingly primitive formation.

[Vide "Outlines of Algologia," sections Nostochina, Fragilline, Byssina, &c.]

(42.) The slimy masses known as Will o' the wisps, or Nostocs, are instances of other allied species, some of which are called by the common people " flowers of heaven;" a name which they deserve more than many that are often given to plants, if it be true, as the old herbalists declare, that, "infused in brandy, they cause a disgust to that liquor in those who drink of it;" for, as Johnston adds, they would then become "an excellent remedy for the 'potatores summi.""

(43.) Not one of the least curious of the lowly flags is the "red snow," which excited so much attention on Captain Ross's return from the North Pole in 1819. This phenomenon seems in some cases to depend upon the sudden appearance of a very minute plant, which the microscope declares to consist of small cells filled with a red fluid, and which is referred to a genus named, from its very simple structure, "Proto-coccus." This plant, as well as the Palmella cruenta, or gory dew, Lepraria kermesina, or bloody rain, with many others called reeks or earthsweats, as well as certain minute animalculæ, will sometimes suddenly appear in such great abundance as even to tinge pools of water with the hue of blood, to make red stains on the sea shore, and to discolour considerable tracts of ground, so as to simulate red snow, or dew or rain; and such in fact the appearance is vulgarly supposed to be. These occurrences are often regarded by the ignorant as of sinister omen; indeed, whole towns have been occasionally alarmed with the report, that, in the course of a single night, the water of their pools had become changed to