" The lymphatics of a plant may be often seen with great ease by merely strip ping- off the cuticle with a delicate hand, and then subjecting it to a microscope ; and in the course of the examination, we are also frequently able to trace the ex istence of a great multitude of valves, by the action of which the apertures of the lymphatics are commonly found closed. Whether the other systems of vegeta ble vessels possess the same Mechanism, we have not been able to determine de cisively : the following experiment, how. ever, should induce us to conclude that they do. If we take the stem of a com mon balsamine, or of various other plants, and cut it horizontally at its lower end, and plunge it, so cut, into a decoction of Brazil wood or any other coloured fluid, we shall perceive that the arteries, or adducent vessels, as also the air ves sels, will become filled or injected by an absorption of the coloured liquor, but that the veins, or reducent vessels, will not become filled ; of course evincing an obstacle in this direction to the ascent of the coloured fluid. But if we invert the stem, and in like manner cut horizontally the extremity which till now was upper most, and plunge it so cut into the same fluid, we shall then perceive that the veins will become injected, or suffer the fluid to ascend ; but that the arteries will not : proving clearly the same kind of obstacle in the course of the arteries in this direction, which was proved to . ex ist in the veins in the opposite direction ; and which reverse obstacles we can scarcely ascribe to any other cause than the existence of valves.
" By this double set of vessels, more over, possessed of an opposite power, and acting in an opposite direction, the one to convey the sap or vegetable blood for wards, and the other to bring it back wards, we are able very sufficiently to establish the phenomenon of a circulatory system." The author admits that no experiments, nor observations, have been able to de tect the existence of muscular or nervous fibres in vegetables ; but notwithstanding this, in answer to those who maintain the necessity of a regular and alternate con traction and dilatation for the production of a circulatory system, both in animals and vegetables, he says, "still must we admit the competency of other powers to produce the same result, while we reflect on the facility with which the human cutis or skin, an organ destitute of all muscu lar fibres whatever, contracts and relaxes generally on the application of a variety of other powers ; powers different in their nature, and in their effect palpable to the external senses : whilst we recal to mind that it is contracted by austere, and re laxed by oleaginous preparations ; con stringed by cold, and dilated by warmth : and that the opposite passions of the mind have a still more powerful influence on the same organ, since fear, apprehension, horror, will not only freeze and corrugate the skin, but in the language of the poet, which is also the language of nature, freeze the blood itself, making '—each particular hair to stand on end Like quills upon the fretful porcupine :' while hope, pleasure, agreeable expecta tion, smooth, soften, and expand it to an equal degree, and, figuratively, perhaps literally, lubricate it with the oil of joy.
Moreespecially must we come to this con clusion, while in conjunction herewith, we survey, in various species of the vegetable kingdom, as strong a contractility and irri tability as are to be met with in the most contractile and irritable muscles of the most sentient animals.
"Yet, could it even be proved that the vessels of plants are incapable of being made to contract by any power whatever, still should we have no great difficulty in conceiving a perfect circulatory system in animals or vegetables without any such cause, whilst we reflect that one half of the circulation of the blood in man him self is accomplished without such a con trivance; and this, too, the more diffi cult half; as every one knows that the veins have, for the most part, to oppose the attraction of gravitation, instead of being able to take advantage of it.
"To argue, therefore, against the exist ence of a circulation of blood, or sap, in plants, from the single circumstance that we are not able to prove demonstrably their possession either of muscular fibres, or of a regular systole and diastole, is merely to argue ex ignorantid, and in de fiance of facts and experiments, which, if not absolutely decisive, are perhaps as decisive as the nature of the case will allow." Having established this point,the author proceeds to point out some striking re semblances in plants to the economy and habits of animals. To these we can but briefly allude.
Plants, like animals, are propagated by sexual connection : "although among vegetables we meet with a few instances of propagation by other means, as, for instance, by slips and offsets, or by buds and bulbs, the parallelism, instead of being hereby diminished, is only drawn the closer ; for we meet with just as many instances of the same varieties of propa gation among animals. Thus the hydra, or polype, as it is more generally called,the asterias, and several species of the leech, as the hirudo viridis, for example, are uniformly propagated by lateral sections, or instinctive slips or offsets; while almost every genus of zoophytic worms is only capable of increase by buds, bulbs, or knobs.
" The blood of plants, like that of ani mals, instead of being simple, is com pound, and consists of a great multitude of compacter corpuscles, globules for the most part, but not always globules, float ing in a looser and almost diaphanous fluid. From this common current of vita lity, plants, like animals, secrete a vari ety of substances of different, and fre quently of opposite powers and qualities, —substances nutritive, medicinal or de structive, And as in animal life, so also in vegetable, it is often observed that the very same tribe, or even individual, that in some of its organs secretes a whole some aliment, in other organs secretes a deadly poison. As. the viper pours into the reservoir situated at the bottom of his hollow tusk a fluid fatal to other ani mals, while in the general substance of his body he offers us not only a healthful nutriment, but in some sort, an antidote for the venom of his jaw : so the jatropha manihot, or Indian cassava, secretes a juice extremely poisonous in its root, while its leaves are regarded as a com mon esculent in the country, and are eaten like spinach-leaves among our selves.