Imágenes de páginas

the vegetable kingdom an inexhaustible fund for a new species of poetic personification ; and extracted from it abundance of luscious and intoxicating sweets; et Linné and the sexual system are surely not answerable, for the distortions which their principles may receive in the brain of a sensualist. It was necessary for Linné to adapt the whole terminology of his system, to the grand hypothesis with which it should stand or fall; every class, every order, every genus, was founded on the principle, that there must be two sexes in every plant. If this proved true, he knew that his classes, orders, and genera, would also be acknowledged; if it was disproved, he was conscious that they had to hope for no reprieve. In order to place what he esteemed, and what has since proved to be the truth, in the strongest light, he was obliged to make use of the expressions in question: they were submitted to the examination, and intended for the information, of cool reason and philosophy, not designed to amuse or to stimulate the imagination.

Yet, however incontrovertible the maxim of Linné may be, and however proper in itself the language of his system, we cannot deny that, in the eyes of a novice, it has somewhat of indelicacy. But, in the instruction of young persons, particularly of the sex whose naturally fine and just feelings of propriety it is the study of every man of principle to avoid wounding, expressions will occur, at which the teacher hesitates, or perceives by the countenance of his pupil that he ought to have hesitated. Nor, perhaps, are parents to blame, who think a science, however delightful, too dearly purchased at the expense of such a blush. The author, therefore, who would give us an Introduction to Botany, and consequently to the Linnean system, expressed in terms which should not admit of a licentious construction, while, at the same time, it conveyed a thorough knowledge of the fundamental principles, would merit the thanks of all parents and teachers, who are desirous of opening to their chil. dren'a perpetual source of innocent relaxation, healthful exercise, and serene delight. We are happy to introduce Dr. Smith's work, as fully answering this description. The principle of the system now stands alone, on the firm basis of experience; it needs no longer the support or confirmation of continual references: the terminology therefore, in as far as it could be in the slightest degree offensive, has been exchanged for one, that is unobjectionable, yet equally scientific and clear; so that the path of the learner is freed from every obstacle or danger, yet deprived of no truth.

The author's design, as intimated in the preface, is to offer an introductory publication, easy, comprehensive, and fit for general use. But though the principal intention, which he


has kept in sight through the whole of this work, is to lay a firm foundation in the mind of the beginner; we should greatly depreciate its value, if we considered it as unworthy the attention of those who have made farther advances in the study. It is a book which will be perused with satisfaction, even by those who do not intend to prosecute the science extensively ; it will prevent the tyro from misconceptions, and narrow views of the science, which too often subvert its utility, by contracting instead of enlarging the mind; and we believe few professed botanists will fail of deriving from it, either additional information, useful hints, or a more luminous view of subjects with which they are already acquainted. If we occasionally regret, that the author has not favoured us more decisively with his own opinion, we must, at the same time, give him credit, for the candour with which he adopts the approved ideas of others, unlike many, who suggest hypo. theses, contrary to their own conviction, in order to appear more important and more original in the eyes of their readers. Dr. S. has judiciously preferred enlightening, with a clear and mild, though often borrowed light, to dazzling with the meteoric splendour of useless originality, which confers no permanent honour upon the author, and thickens the obscurity round those whom he affects to illuminate.

The work begins with a Dedication to the Bishop of Durham; a preface follows, in which Dr. S. considers the advantages of the study of Botany in a manner unusually extensive and elegant. He commences his work, by separating the class of objects elucidated by this science, from the two other kingdoms of nature, and justly remarks the difficulty that exists in distinguishing them by definition from animals, though the uncertainty vanishes in practice. The illustrious Hedwig perceived this imperfection, and proposed a distinction, which he thought more general than the locomotion of Ludwig, or the nutrition of Boerhaave; but our author seems to acquiesce in Mirbel's improvement on Boerhaave, that vegetables are supported by inorgánic, animals by organic matter. We however consider several of the fungi, (e. g. the genera Sphæria and Oxygena) as exceptions; as they appear totally incapable of growth, without the presence of matter that has been organized. In the nine following chapters, Dr. S. gives a very perspicuous outline of the anatomy and physiology of the inner parts of vegetables; with respect to the former, he principally follows Mirbel, though without omitting the opinions and experiments of Grew, Malpighi, Du Hamel, Bonnet, and Dr. Hope; in the latter he generally agrees with Mr. Knight's satisfactory theory of vegetation. He seems inclined, however, to think the medulla, or pith, an organ

of greater importance than a mere reservoir of moisture, and rather analogous to the nervous system in the animal kingdom. Some such view of it indeed seems authorized by its central defended situation, the state in which it is found during the most vigorous vegetation of the plant, its accumulation in the thickened flowerstalks of many plants, and immediately beneath the umbel in such as are furnished with one, and also by the experiments of Mr. Lindsay, which prove it the seat of irritability. With respect to the situation and use of the sap vessels, there can be little doubt, in trees and shrubs; and Di. S. has ingeniously adapted the explanation to the palms, and some others of the monocotyledones : but much, we presume, remains still to be explored, particularly in some of the canes, the plantæ aphyllæ, the stipes of Agaricus and Boletus. The tenth chapter, treating of secretions, though it abounds with interesting and instructive matter, would have been still more satisfactory, if the different substances, prepared by the vegetable economy, had been chemically arranged. There are, indeed, many among them, which elude the most refined accuracy of the art; but the majority would be more perfectly understood, by such a disposition. While the production of silica, or elementary flint, in the Tabaxir of the Bamboo, certainly deserved notice, as a very distinguished phenomenon, the formation of other earths, and even metallic substances, ought not to have been omitted. Lamarck's experiment, proving the production of heat in the spatbe of Arum maculatum or Wake robin, dieserves the attention of every curious observer; and we hope, as the plant is sufficiently common in many parts of England, that it will soon be perfectly investigated. We transcribe the passage, with the view of exciting the attention of those who may not possess the work.

• The most remarkable account that has fallen in my way concerning the production of heat in plants, is that given by Lamarck'in his Flore Françoise, v. 3. 538, of the Common Årum maculatum, Engl. Bot. t. 1298, (the white-veined-variety,) the flower of which, at a certain period of its growth, he asserts to be, for a few hours, “ so hót as to seem burning.” The learned M. Senebier of Geneva, examining into this fact, discovered that the heat began when the sheaih was about to open, and the cylindrical body within just peeping forth ; and that it was perceptible from about three or four o'clock in the afternoon till eleven or twelve at night. Its greatest degree was seven of Reaumur's scale above the heat of the air, which at the time of his observation was about fourteen or fifteeni of that thermometer.'

After having described and explained the inner organs of plants, our author makes the transition, by a chapter treating of the process of vegetation, particularly in as far as the cotyledones are concerned, to the consideration of the appearance and functions of the external organs. In classifying and dis


[ocr errors]

tinguishing these, he generally follows Linné's Philosophia Botanica, adding a short explanation of the terms made use of, with a reference to familiar examples, or approved plates; but interweaves the whole, with original observations, and occasional criticisms, so as to render it very different from a meagre index. His observations on the roots of several of the Orchis tribe, well known to be very difficult of cultivation, particularly deserve notice, and may convey hints to the practical gardener, how to attempt their domestication with better success. When considering the bud as a means of propagating the species, he assents to Mr. Knight's opinion, that all increase in this manner is only an extension of the same individuay, not a real progeny, and is therefore limited in duration. The argunents in favour of this hypothesis are certainly numerous and strong; and though it may seem improbable at first sight, a closer consideration of the subject, we believe, will induce every unprejudiced person to think it the most natural. Indeed, probable conjecture is the only extent to which it can be established, as many ages of observation would be requisite to discover the period in which, for instance, the common garden Rose, the Artemisia Abrotanum, or Southern wood, and many plants with creeping roots, which seld m perfect their seeds, and which appear extensible ad infinitum, would be totally exhausted and require a regular reproduction. We are less inclined to a lopt his curious explanation of the Sarracenia and Nepenties, which, if it be correct, furnishes another objection to Mirbel's definition. The passage is so ingenious, that we submit it entire to the judgement of our readers.

• The economy of the Sarracenia, an American genus of which we now know four species, and of the East Indian Nepenthes distillatoria deserves particular mention. Both grow in bogs, though not absolutely in the water.

The former genus has tubular leaves which catch the rain like a funnel and retain it: at least such is the nature of s. purpurea, Curt. Mag. t. 849, whose margin seems dilated expressly for this purpose, while the orifice of the tubular part just below is contracted to restrain evaporation. Linnæus conceived this plant to be allied in constitution t. Nymphea, and consequently to require a more than ordinary supply of water, which its leaves were calculated to catch and to retain, so as to enable it to live without being immersed in a river or pond.

But the consideration of some other species renders this hypothesis very doubtful. S. flava, t. 780, and more especially S. adunca, Exot. Bot. t. 53, are so constructed that rain is nearly excluded from the hollow of their leaves, and yet that part contains water, which seems to be secreted by the base of each leaf. What then is the purpose of this unusual contrivance ? An observation communicated to me two years ago, in the botanic garden at Liverpool, seems to unravel the mystery. An insect of the Sphex or Ichneumon kind, as far as I could learn from description, was seen by one of the gardeners to drag several large flies to the Sarracenia adunca, and, with some difficulty forcing them under the lid or cover of its leaf, to deprisit them in the tubular part, which was half filled with water. All the leaves, on being examined, were found crammed with dead or drowning flies. The $. purpurea is usually observed to be stored with putrefying insects, whose scent is perceptible as we pass the plant in a garden; for the margin of its leaves is beset with inverted hairs, which, Jike the wires of a mousetrap, render it very difficult for any unfortunate fily, that has fallen into the watery tube, to crawl out again. Probably the air evolved by these dead flies may be beneficial to vegetation, and, as far as the plant is concerned, its curious construction


be designed to entrap them, while the water is provided to tempt as well as to retain them. The Sphex or Ichneumon, an insect of prey, stores them up unquestionably for the food of itself or its progeny, probably depositing its eggs in their carcases, as others of the same tribe lay their eggs

in various caterpillars, which they sometimes bury afterwards in the ground. Thus a double purpose is answered ; nor is it the least curious circumstance of the whole, t' at an European insect should find out an American plant in a hot-house, in order to fulfil that purpose.

• If the above explanation of the Sarracenia be admitted, that of the Nepenthes will not be difficult. Each leaf of this plant terminates in a sort of close-shut tube, like a tankard, holding an ounce or two of water, certainly secreted through the footstalk of the leaf, whose spiral-coated vessels are uncommonly large and numerous. The lid of this tube either opens spontaneously, or is easily lifted up by insects and small worms, who are supposed to resort to these leaves in search of a purer beverage than the surrounding swamps afford. Rumphius, who has described and figured the plant, says 66 various little worms and insects crawl into the orifice, and die in the tube, except a certain small squilla or shrimp, with a protuberant back, sometimes met with, which lives there."- I have no doubt that this shrimp feeds on the other insects and worms, and that the same purposes are answered in this instance as in the Sarracenia. Pro. bably the leaves of Dionæa muscipula, as well as of the Drosere, Engl. Bot, t. 867—69, catch insects for a similar reason.' pp. 195–198.

The Roots, Stems, Buds, Leaves, and their functions, Fulcra, or appendages, manner of Inflorescence, and parts of Fructification, form the subjects of as many distinct chapters, and are succeeded by one on the peculiar functions of the Stamens and Pistils, in which Dr. S. relates the history of the discovery of their importance, and the arguments in proof of it, in a particularly happy manner; nor is it from fear of fatiguing the patience of our readers, that we resist the temptation of transcribing the whole latter part of it, and insert only the following short passage.

• But of all Aowers that of the Barberrybush t. 49, is most worthy the attention of a curious physiologist. In this the six stamens, spreading moderately, are sheltered under the concave tips of the petals, till some extraneous body, as the feet or trunk of an insect in search of honey, touches the inner part of each filament near the bottom. The irritability

« AnteriorContinuar »