or the alluvial and volcanic, are still forming, and have been, ever since the great work of creation was completed, the precise duration of the last two days of creative labour can have no influence upon this question. But to a plain yet attentive reader of the Mosaic account even these two days must, I think, appear to have been of a far more protracted length than that of twenty-four hours each, and especially the sixth day; for it is difficult to conceive how the first parent of mankind could have got through the vast extent of work assigned to him within the short term of twelve or fourteen hours of daylight, without a miracle, which is by no means intimated to us, and as difficult to suppose that he was employed through the night. On this last day were created, as we learn from Gen. i. 24-28, all the land-animals after their kind, cattle, and wild beasts, and reptiles; then Adam himself, but alone; who was next, as we learn from ch. ii. 15-22, taken and put into the garden of Eden, to dress it and to keep it; where he had explained to him the trees he might eat of, and the tree he might not; after which were brought to him, that he might make himself acquainted with their respective natures, every :beast of the field and every fowl of the air; to all of whom he gave names as soon as their respective characters became known to him. Subsequently to which (for at this time, v. 20, there was not found a help-meet for him), he was plunged into a deep sleep, when the woman was formed out of a part of [himself, which completed the creative labour of this last day alone.

That the same Almighty Power who created light by a word, saying TIN T'I DIN "be light! and light was,"* could have ruled the whole of this, or even formed the universe, by a word, as well, is not to be doubted; but as both the book of revelation and the book of nature concur in telling us that such was not the fact, and that the work of creation went on progressively, and under the influence of a code of natural laws, we are called upon to examine into the march of this marvellous progress by the laws of nature referred to, and to understand it by their operations. Nor is it more derogatory to Him with whom a thousand years are as one day, and one day as a thousand years, to suppose that He allotted six hundred or six thousand years to the completion of his design, than that He took six solar days for the purpose; and surely there is something far more magnificent in conceiving the world to have gradually attained form, order, and vitality, by the mere operation of powers communicated to it in a state of chaos, through a single command, which instantly took effect and commenced, and persevered and perfected the design proposed, than in conceiving the Almighty engaged in personal and continuous exertions, though for a more limited period of time. Thus, in progressive order, uprose the stupendous system of the world: the bright host of morning stars shouted together on its birth-day; and the eternal Creator looked down with complacency on the finished fabric, and “saw that it was good."

LECTURE VIII.

ON ORGANIZED BODIES, AND THE STRUCTURE OF PLANTS COMPARED WITH THAT OF ANIMALS.

FROM the unorganized world, which has formed the main subject of our last two lectures, let us now rise a step higher in the scale of creation; and ascend from insentient matter to life, under the various modifications it assumes, and the means by which it is upheld and transmitted.

If I dig up a stone, and remove it from one place to another, the stone will suffer no alteration by the change of place; but if I dig up a plant and remove it, the plant will instantly sicken, and perhaps die. What is the cause of this

• Gen. i. 3
F

difference? Both have proceeded from a minute molecule, a nucleus or a germ; both have a tendency to preserve their derivative or family configuration, and both have been augmented and perfected from one common soit. If I break the stone to pieces, every individual fragment will be found possessed of the characteristic powers of the aggregate mass; it is only altered in its shape and magnitude: but if I tear off a branch from the plant, the branch will instantly wither, and lose the specific properties of the parent stock.

No external examination, or reasoning à priori will explain this difference of effect. It is only by a minute attention to the relative histories, interior structures, and modes of growth of the two substances, that we are enabled to offer any thing like a satisfactory answer; and by such examination we find that the stone has been produced fortuitously, has grown by external accretion, and can only be destroyed by mechanical or chemical force; while the plant has been produced by generation, has grown by nutrition, and been destroyed by death: that it has been actuated by an internal power, and possessed of parts mutually dependent and contributory to each other's functions. In what this internal power consists we know not. Differently modified, we meet with it in both plants and animals; and wherever we find it we denominate it the principle of life, and distinguish the individual substance it actuates by the name of an organized being. And hence, all the various bodies in nature arrange themselves under the two divisions of organized and unorganized: the former possessing an origin by generation, growth by nutrition, and a termination by death; and the latter a fortuitous origin, external growth, and a termination by chemical or mechanical force.

This distinction is clear, and it forms a boundary that does not seem to be broken in upon by a single exception. In what, indeed, that wonderful power of crystallization consists, or by what means it operates, which gives a definite and geometrical figure to the nucleus or primary molecule of every distinct species of crystal; and which, with an accuracy that laughs at all human precision, continues to impress the same figure upon the growing crystal through every stage of its enlargement, thus naturally separating one species from another, and enabling us to discriminate each by its geometrical shape alone we know not: but even here, where we meet with an approach towards that formative effort, that internal action and consent of parts which peculiarly characterize the living substance, there is not the smallest trace of an organized arrangement; while the origin is clearly fortuitous, and the growth altogether external, from the mere apposition of surrounding matter. So, on the other hand, in corals, sponges, and fuci, which form the lowest natural orders among animals and vegetables, and the first of which seems to constitute the link that connects the animal and vegetable with the mineral world, for it has in different periods been ascribed to each,-simple as is their structure, and obtuse as is the living principle that actuates them, we have still sufficient marks of an organized make; of an origin by generation, the generation of buds or bulbs, of growth by nutrition, and of termination by death. But the animal world differs from the vegetable as widely as both these differ from the mineral. How are we to distinguish the organization of animals from that of plants ?-In what does their difference consist? and here I am obliged to confess, that the boundary is by no means so clearly marked out; and that we are for the most part compelled to characterize the difference rather by description than by definition. Nothing, indeed, is easier than to distinguish animals and vegetables in their more perfect states: we can make no mistake between a horse and a horse-chestnut tree, a butterfly and a blade of grass. We behold the plant confined to a particular spot, deriving the whole of its nutriment from such spot, and affording no mark either of consciousness or sensation; we behold the animal, on the contrary, capable of moving at pleasure from one place to another, and exhibiting not only marks of consciousness and sensation, but often of a very high degree of intelligence as well. Yet, if we hence lay down consciousness or sensation, and locomotion, as the two characteristic features of animal life, we

shall soon find our definition untenable; for while the Linnæan class of worms affords instances, in perhaps every one of its orders, of animals destitute of locomotion, and evincing no mark of consciousness or sensation, there are various species of plants that are strictly locomotive, and that discover a much nearer approach to a sensitive faculty.

However striking, therefore, the distinctions between animal and vegetable life, in their more perfect and elaborate forms, as we approach the contiguous extremities of the two kingdoms we find these distinctions fading away so gradually,

Shade, unperceived, so softening into shade,

and the mutual advances so close and intimate, that it becomes a task of no common difficulty to draw a line of distinction between them, or to determine to which of them an individual may belong. And it is probable, that that extraordinary order of beings called zoophytes, or animated plants, as the term imports, and which by Woodward and Beaumont were arranged as minerals,* and by Ray and Lister as vegetables, have at last obtained an introduction into the animal kingdom,† less on account of any other property they possess, than of their affording, on being burnt, an ammoniacal smell like that which issues from burnt bones, or any other animal organs, and which is seldom or never observed from burnt vegetable substances of a decided and unquestionable character. Ammonia, however, upon destructive distillation, is met with in small quantities in particular parts of most if not of all vegetables, though never perhaps in the whole plant. Thus it occurs slightly in the wood or vegetable fibre; in extract, gum-mucilage, camphor, resin, and balsam; gumresin, gluten, and caoutchouc: besides those substances that are common to both animals and vegetables, as sugar, fixed oil, albumen, fibrine, and gelatine. There are some plants, however, that even in their open exposure to a burning heat give forth an ammoniacal smell closely approaching to that of animal substance. The clavarias or club-tops, and many other funguses, do this. But a distinction in the degree of odour may even here be observed, if accurately attended to. Yet the clavarias were once regarded as zoophytes, and are arranged by Millar in the same division as the corals and corallines. M. de Mirbel, in his very excellent treatise "On the Anatomy and Physiology of Plants," has endeavoured to lay down a distinction between the animal and the vegetable world in the following terms, and it is a distinction which seems to be approved by Sir Edward Smith; "Plants alone have a power of drawing nourishment from inorganic matter, mere earths, salts, or airs; substances incapable of nourishing animals, which only feed on what is or has been organized matter, either of a vegetable or animal nature. So that it should seem to be the office of vegetable life alone to transform dead matter into organized living bodies." Whence another learned French physiologist, M. Richerand, has observed that the aliments by which animals are nourished are selected from vegetable or animal substances alone; the elements of the mineral kingdom being too heterogeneous to the nature of animals to be converted into their own substance without being first elaborated by vegetable life; whence plants, says M. Richerand, may be considered as the laboratory in which nature prepares aliment for animals.

* Phil. Trans. xiii. 277.

† Parkinson's Organic Remains, f. 23, ií. 157, 158.

Several species of this genus of fungi have very singular properties: thus the c. haematodes has so near a resemblance to tanned leather, though somewhat thinner and softer, as to be named oak-leather club-top, from its being chiefly found in the clefts and hollows of oak-trees. In Ireland, it is employed as leather to dress wounds with; and, in Virginia, to spread plasters upon.

There are some cryptogamic plants, and especially among the mosses, that can be hardly made to burn by any means. Such is the fontinella antipyretica, so called on this very account; and which is hence in common use among the Scandinavians, as a lining for their chimney sides, and the inside of their chimneys, by way of preservation. So that here we have an approach to mineral instead of to animal substances, and especially to the asbestos and other species of talcose earths. There is one species of byssus, another curious genus of mosses, that takes the specific name of asbestos from this very property. It is found in the Swedish copper mines of Westmann-land in large quantities, and when exposed to a red heat instead of being consumed, is vitrified.

Traité d'Anatomie et de Physiologie Végétale, i. 19.
Elemens de Physiologie, &c. cap de la Digestion

I concur with these elegant writers in admitting the beautiful and harmo nious relation so obviously established between minerals, plants, and animals; but it is at the same time impossible to allow of the distinction between vegetable and animal life here laid down; because, first, vegetables are by no means nourished exclusively, as, indeed, M. Mirbel himself frankly allows, from terrene elements; and, secondly, because animals are as little nourished exclusively from vegetable materials. Among insects, worms, and even fishes, there are many tribes that derive by far the greater portion of their increase from the mineral kingdom alone; while even in man himself, air, water, common salt, and lime, which last is almost always an ingre dient of common salt, are substances indispensable to his growth, and are derived immediately from the mineral kingdom.

In laying down, therefore, a distinctive character for animals and plants, we are compelled to derive it from the more perfect of each kind; and to leave the extreme cases to be determined by the chemical components elimi nated on their decomposition. And under this broadview of the subject I now proceed to observe, that while they agree in an origin by generation, a growth by nutrition, and a termination by death; in an organized structure, and an internal living principle; they differ in the powers with which the living principle is endowed, and the effects it is capable of exerting. In the plant it is limited, so far as we are capable of tracing it, to the properties of irritability, contractility, and simple instincts; in the animal it su peradds to these properties those of muscularity, sensation, and voluntary motion.

There have been, indeed, and there still are, physiologists who,-not ad verting to the extraordinary effects which the power of irritability is capable of producing when roused by different stimulants, and under the influence of an internal and all-pervading principle of life, operating by instinctive laws and instinctive actions, or those, as we shall show hereafter, which are spe cially directed to the growth, preservation, or reproduction of a living frame, or any particular part of it,-have conceived plants as well as animals to be possessed of sensation and muscular fibres; and as sensation is the result of a particular organ, and the organ producing it is connected with various others, have at the same time liberally endowed them with a brain, a heart, and a stomach; and have very obligingly permitted them to possess ideas, and the means of communicating ideas; to fall in love and to marry, and thus far to exercise the distinctive faculty of volition. The whole of which, however, is mere fancy, grounded altogether upon an erroneous and contracted view of the effects of the principle of irritability when powerfully excited by the influence of light, heat, air, moisture, and other causes.

In reality, such kinds of loves and intermarriages are not peculiar to plants, but are common to all nature: they exist between atom and atom, and the philosopher calls them attractions; they exist between congeries and congeries, and the chemist calls them affinities; they exist between the iron and the loadstone, and every one denominates them magnetism. Nor let it be said that in these cases of mutual union we have nothing more than a mere aggregation of body; for we have often a third substance produced, and actually generated, as the result of such union, far more discrepant from the parent substances both in quality and feature than are ever to be met with in vegetable or animal life. Thus, if an acid be married to an alkali, the progeny brought forth will be a neutral salt, possessing not the remotest resem blance to the virtues of either of its parents. In like manner, if alkohol be married to any of the more powerful acids, and the banns be solemnized over an altar of fire, but not otherwise, the offspring engendered will be a substance called ether, equally unlike both its parents in its disposition. But the form or features are as frequently changed as the temper. Thus, if we unite olive oil, which is a liquid, with some of the oxides of lead, which are pow ders, the result is neither a liquid nor a powder, nor a medium of the two, which would be a paste, but the hard adhesive plaster usually called diachylon. So, again, if muriatic acid, which is a liquid, sport in dalliance with the

volatile nymph ammonia, which is an invisible gas, the fruit of their embraces will be still more extraordinary in point of form, for the gas and the liquid 1 will engender that solid substance commonly known by the name of sal ammoniac, or, in the new nomenclature, muriate of ammonia. In like manner, y our common smelling salts, or carbonate of ammonia, though a hard, concrete ecrystallization, are the mere result of the union of two invisible gases, ammonia and carbonic acid gas, or fixed air; and which, having duly paid their court to each other, give birth to this solid substance.

But in all this it may be said that we have no instance of a multiplication of species; nor in reality of any thing more than the production of a third substance, issuing, like the fabled phœnix of antiquity, out of the ashes or decomposition of the parent stock; yet in many cases we have instances of multiplication also--and instances far more extraordinary and far more prolific than are ever to be found in the multiplication of either animals or vegetables. Such especially are those wonderful increases that occur in the case of ferments and of contagions. A few particles of yest lying dormant in a dessert-spoon are introduced into a barrel of beer, or of any other fer mentable fluid, and in a few hours propagate their kind through the largest vessel that was ever manufactured; so that at length every particle of the fluid is converted into a substance of their own nature. A few pestilential miasms are thrown forth from a stagnant marsh or a foul prison, and give birth instantaneously to myriads and myriads of the same species of particles, till the atmosphere becomes impregnated with them through a range of many miles in diameter. Two or three particles of the matter of plague are packed up in a bag of cotton at Aleppo, and are many months afterward set at liberty in Great Britain. Aided by the stimulus of the air, they instantly set to work, and procreate so rapidly, that the whole country in less than a week is laid prostrate by the enormity of their increase.

Now the terms loves and marriages will just as well apply to all these as to the vegetable creation. The cause of the respective unions, and of the changes that take place in consequence of such unions, are in both cases nothing more than elective attractions: in the mineral and gaseous kingdoms produced by what chemists have denominated the principle of affinity, and in the vegetable by what physiologists have called the principle of irritability; a principle far nicer and nobler and more delicate than that of affinity, and under the influence of an internal, an all-pervading, and identifying vital power, capable, as differently excited by different stimulants, of producing far nicer and nobler, more delicate and more complicated effects; but which in itself is not more different from the principle of affinity than it is from that of sensation.

No experiment or observation has hitherto proved vegetables to be pos sessed of any higher powers than those of irritability, contractility, and those instinctive energies which we shall hereafter show are dependent upon the principle of life.

It is almost superfluous to observe, in this place, that there are also powers and faculties of a much higher character than any I have yet noticed, appertaining to the nobler ranks of animals; for at present I am only pointing out the leading characters by which animals in general may be distinguished from vegetables in general, and shall have sufficient opportunities, as we proceed, of adverting to these additional faculties, and of investigating their respective excellencies.

Our immediate concern, then, is with VEGETABLE LIFE; its general laws, structure, and phenomena. And upon this subject I shall touch as briefly as possible, intending it as a mere vestibule or introduction to the more important study of animal philosophy.

Plants, then, like animals, as I have already observed, are produced by generation, and through the medium of ova, or eggs. The exceptions to this common rule are few, and they occur equally in both kingdoms. The egg of the plant is its seed; a doctrine not of modern origin, but taught and understood quite as clearly, and with as close a reference to the rise of animal