Sec. IV. Their Pulmonary Arteries and Veins. IX. The Growth of Seeds, Buds, and Bulbs. XIV. Difeafes of Plants. Part III. Agriculture, and Horticulture. XVI. Production of Seeds. XVII. Production of Roots and Barks. XIX. Production of Flowers. XX. Plan for difpofing a Part of the Syftem of Linneus into more natural Claffes and Orders. Appendix.-Improved Conftruction of the Drill Plough. In the firft fection, this author afferts that plants are inferior animals; that every bud of a tree is an individual vegetable being, and therefore a tree is a family or fwarm of individual plants, like the polypus with its young growing out of its fides, or like the branching cells of the coral-infect. "In the inoculation," he fays, "and ingrafting of fruit-trees, five or fix different kinds of pears are frequently feen on the branches of one tree, which could not then properly be termed an individual being." In fupport of those affertions, Dr. Darwin adduces a variety of obfervations, or rather verbal than phyfical diftinctions. He alfo fpecifies the difference between animals and vegetables in the following words. "As vegetables are immovably fixed to the foil, from whence they draw their aliment ready prepared, and this uniformly, and not at returning intervals; it follows, that in examining their anatomy, we are not to look for muscles of locomotion, as legs and arms; nor for or gans to receive and prepare their aliment as a mouth, throat, ftomach, and bowels, by which contrivances animals are enabled to live many hours without new fupplies of food from without. "The parts, which we may expect to find in the anatomy of vege tables, which correfpond to thofe in the animal economy, are firit a threefold fyftem of abforbent veffels, one branch of which is defigned to imbibe the nutritious moisture of the earth, as the lacteals imbibe the chyle from the stomach and intestines of animals; another to imbibe the 1 the water of the atmosphere, opening its mouths on the cuticle of the leaves and branches, like the cutaneous lympathic veffels of animals; and a third to imbibe the secreted fluids from the internal cavities of the vegetable fyftem, like the cellular lymphatics of animals. "Secondly, in the vegetable fetus, as in feeds or buds, another fyftem of absorbent veffels is to be expected, which may be termed umbilical vessels, as defcribed in Sect. III. of this work, which fupply nutriment to the new bud or feed, fimilar to that of the albumen of the egg, or the liquor amnii of the uterus; and also another system of arterial veffels, which may be termed placental ones, correfponding with thofe of the animal fetus in the egg or in the womb, which fupply the blood of the embryon with due oxygenation before its nativity. "Thirdly, a pulmonary fyftem correfpondent to the lungs of aerial animals, or to the gills of aquatic ones, by which the fluid abforbed by the lacteals and lymphatics may be expofed to the influence of the air. This is done by the leaves of plants, or the petals of flowers; those in the air refembling lungs, and thofe in the water refembling gills. "Fourthly, an arterial system to convey the fluid thus elaborated to the various glands of the vegetable for the purpofes of its growth, nutrition, and fecretions; and a fyftem of veins to bring back a part of the blood not thus expended. "Fifthly, the various glands which feparate from the vegetable blood the honey, wax, gum, refin, ftarch, fugar, essential oil, and other fecretions. "Sixthly, the organs adapted to the lateral or viviparous generation of plants by buds, or to their fexual or oviparous propagation by feeds. Seventhly, longitudinal mufcles to turn their leaves to the light, and to expand or close their petals or their calyxes; and vafcular muscles to perform the absorption and circulation of their fluids, with their attendant nerves, and a brain, or common fenforium, belonging to each individual feed or bud; to each of which we shall appropriate an explanatory fection." P. 5. And further on he says; "Now as the internal pith of a bud appears to contain or produce the living principle, like the brain and inedulla oblongata, or spinal marrow of animals, we have from hence a certain criterion to diitinguish one bud from another, or the parent bud from the numerous budlets, which are its offspring, as there is no communication of the internal pith between them." P. 8. At the end of this fection the reader is inclined to afk, what can all this mean i The fecond fection contains a variety of óbfervations, the importance of which may be gathered from the following quotations. After defcribing how the abforbent veffels of plants may be rendered vifible, namely, by placing twigs of a fig-tree, or of B BRIT. CRIT. VOL. XVIII, JULY, 1801. feveral feveral other plants, for a fhort time in a decoction of log-wood, or madder, &c. and then viewing them through a common magnifying-glafs, he fays, "These abforbent veffels have been called bronchia by Malpighi and Grew, and fome other philofophers, and erroneoufly thought to be air-veffels; in the fame manner as the arteries of the human body were fuppofed to convey air by the antients, till the great Harvey by more exact experiments and jufter reasoning, evinced that they were blood veffels. This opinion has been fo far credited because air is feen to iffue from wood, whether it be green or dry, if it be covered with water, and placed in the exhausted receiver of an air-pump; and thefe veffels have therefore been fuppofed to constitute a vegetable refpiratory organ; but it will be fhewn hereafter, that the leaves of plants are their genuine lungs, and that the absorbent veffels and arteries become accidently filled with air in the dead parts of vegetables. "For as the veffels of vegetables are very minute, and have rigid coats, their fides do not collapfe when they are cut or broken, as their juices flow out or exhale; they must therefore receive air into them.” P. 12. "There are neverthelefs certain horizontal veffels of large diameter, which pafs through the bark of trees to the alburnum, which probably contain air, as they are apparently empty, I believe, in the living vegetable; for the bark of trees confifts of longitudinal fibres, which are joined together, and appear to inofculate at certain distances, and recede from each other between those distances like the meshes of a net, in which spaces feveral horizontal apertures are feen to penetrate through the bark to the alburnum, according to Malpighi, who has given a figure of them, which is copied in Plate I. Fig. 2. of this work. Very fine horizontal perforations through the bark of trees are also mentioned by Duhamel, which he believes to be perfpiratory or excretory organs, but adds, that there are others of much larger diameter, fome round and fome oval, and which in the birch-tree ftand prominent, and pierce the cuticle or exterior bark." P. 13. "These horizontal veffels I fuppofe to contain air inclosed in a thin moist membrane, which may ferve the purpose of oxygenating the fluid in the extremities of fome fine arteries of the embryon buds, in the fame manner as the air at the broad end of the egg is believed to oxygenate the fluids in the terminations of the placental vessels of the embryon chick." P. 14. "The abforbent veffels of vegetables, like those of animal bodies, are liable to err in the selection of their proper aliment, and hence they fometimes drink up poisonous fluids, to the detriment or deftruction of the plant. Dr. Hales put the end of a branch of an apple-tree, part of which was previously cut off, into a quart of rectified fpirit of wine and camphor, which quantity the ftem imbibed in three hours, which killed one half of the tree. Veg. Stat. p. 43. Some years ago I fprinkled on fome branches of a wall-tree a very flight folution of arfenic, with intent to deftroy infeets; but it at the fame time deftroyed the branches it was thrown upon. And I was informed by Mr, Wedgewood, Wedgewood, that the fruit-trees planted in his garden near Newcastle in Staffordshire, which confifted of an acid clay beneath the factitious foil, became unhealthy as foon as their roots penetrated the clay; and on inspection it appeared, that the fmall fibres of the roots, which had thus penetrated the clay, were dead and decayed, probably corroded by the vitriolic acid of the clay, beneath which is a bed of coals. "It is, however, afferted by M. Buffon, that the roots of many plants will creep afide to avoid bad earth, or to approach good. Hift. Nat. Vol. III. But this is perhaps better accounted for by fuppofing, that the roots put out no abforbent veffels, where they are not ftimu lated by proper juices; and that an elongation of roots in confequence only fucceeds, when they find proper nutriment." P. 18. Dr. D. having in the first and fecond fections fufficiently fhown, as he thinks, the fimilarity between feveral vegetable and animal parts, adopts, in the third and fubfequent fections, the terms which have been generally ufed to denote the parts of the latter, in explanation of thofe of the former. Thus, in describing the germination of feeds, he says, "During the great action of these umbilical absorbent veffels the buds become expanded, that is, the young vegetable beings put forth leaves, which are their lungs, and confift of a pulmonary artery, vein, and absorbents, and alfo acquire a new bark over that of the branches, trunk, and roots, of the lait year, which confifts of aortal arteries, veins, and absorbents, and new radicles, which terminate in the foil. At this time the umbilical veffels, which exifted in the alburnum, or fap-wood, cease to act, and coalefce into more folid wood, perhaps fimply by the contraction of the spiral fibre, of which they are composed; and the fwarm of new vegetables, which conftitute a tree, are now nourished by their proper lacteal and lymphatic fyftems." P. 30. The third fection fhows the fimilarity between the generation of animals and of vegetables; the feeds are compared with the eggs, and certain parts of vegetables are fhown to correfpond to certain parts of animals. The like is shown with respect to their nourishment, growth, &c. But this fimilarity, as far as it will go, has occurred to, and has been fhown by, a variety of writers. The contents of the fourth fection are very numerous, and are arranged under the principal heads, of I, Leaves; 2, Aquatic Leaves; 3, Root Leaves; 4, Floral Leaves; 5. And the Coral. The conclufion of this fection is as follows: "We may draw this general refult, that the common leaves of trees are the lungs of the individual vegetable beings, which form during the fummer new buds in their bofoms, whether leaf-buds or flowerbuds, and which in respect to the deciduous trees of this climate perish in autuma; while the new buds remain to expand in the enfuing fpring. Secondly, that the bractes, or floral leaves, are the lungs of the pericarp or uterus, and to the growing feeds which it contains, as the B 2 bractes bractes on the stem of the crown-imperial, fritillaria imperialis, and the tuft above its flowers. And, thirdly, that the corals or petals are the lungs belonging to the anthers and ftigmas, which are the fexual or amatorial parts of the plant, and to the nectaries for the fecretion of honey, and to the other glands which affords effential-oil and wax. "Laftly, the ftamina and ftigma with the petals and nectary, which conftitute the vegetable males, and the amatorial part of the female, as they in fome plants appear before the green leaves or bractes, as in colchicum and mezereon, and in all plants fall off when the female uterus is impregnated, would appear to be diftinct beings, totally different both from the leaf-buds, which produce a viviparous progeny; and also from the bractes with the calyx and pericarp, which constitute the vegetable uterus. "They muft at first receive nutriment from the vernal fap-juice, like the expanding foliage of the leaf-buds, or the bractes of the flower-buds. But when the corol becomes expanded, and conftitutes a new pulmonary organ, the vegetable juices are exposed to the air in the extremities of its fine arteries beneath a moist pellicle for the purpofe of greater oxygenation, and for the important fecretion of honey; and then the anthers and ftigmas are fupplied with this more nutritious food, which they absorb from its receptacle, the nectary, after it has there been exposed to the air, and are thus furnifhed with greater irritability, and with the neceffary amatorial fenfibility, and live like bees and butterflies on that nutritious Auid." P. 55. In the remaining fections of the first part, this author continues to point out, and to illuftrate, the resemblance of vegetable to animal bodies. But it is not in our power to follow him ftep by step in this long illuftration; we cannot, however, forbear tranfcribing the following paragraphs: "This leads us to a curious inquiry, whether vegetables poffefs any organs of fenfe? Certain it is, that they poffefs a fense of heat and cold, another of moisture and drynefs, and another of light and darknefs; for they clofe their petals occafionally from the prefence of cold, moisture, or darkness. And it has been already fhewn, that these ac tions cannot be performed fimply from irritation, because cold and darkness are defective quantities of our ufual stimuli; and that on that account fenfation or volition are employed; and in confequence a fenforium or union of the nerves muft exift. So when we go into the light, we contract the iris, not from any ftimulus of the light on the fine muscles of the iris, but from its motions being affociated with the fenfation of too much light on the retina, which could not take place without a fenforium or center of union of the nerves of the iris with those of vifion. "Befides thefe organs of fenfe, which diftinguish cold, moisture, and darkness, the leaves of mimofa, and of dionæa, and of drofera, and the flamens of many flowers, as of the barberry, and of the numerous clafs of fyngenefia, are fentible to mechanic impact; that is, they poffefs a fenfe of touch; and as many of their diftant muscles are in confequence excited into action, this also evinces that they poffefs a common fenforium, I |