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learned institution, that natural science has taken so elevated a position, and that the physiology of plants has come to be considered as the very stepping stone of that branch of scientific knowledge.

There are, to be sure, illustrious names in England; but for the elementary parts of the science under discussion-for the investigation of fixed principles-where are there such men as Dr. Dutrochet, De Candolle, and others of this class, who have written so copiously, so ably, and so intelligibly, on this one important branch of philosophy-vegetable physiology?

The more minute our investigations in the animal kingdom, the more conspicuous will our ignorance appear; we shall be amazed to think with how much self-complacency we sat down content, under such a tissue of absurdities as disfigured the study before these men enlightened us. The great part which the electric and magnetic fluids take in arranging and propelling organic matter, is still unknown to us; when the time arrives for the full comprehension of the powers and laws of these two great principles, much of the beautiful system of internal organization will be revealed to us.

The life of man will not then hang on so slender a thread; chance, which more or less comes to the aid of the physician, will be succeeded by true knowledge. Man knows that he is born to die, but he knows, likewise, that he may aspire to live out his term-his threescore years and ten. It is his privilege to avert or lessen the evils which tend to shorten his brief career; and nothing is so likely to affect this object, as to become minutely acquainted with the internal structure of organized bodies.

Experiments on plants are conducted with more ease and certainty than on animals, for plants are completely in our power on account of their peculiar passiveness and rigidity. We have the aid, too, of good glasses and ingenious instruments; dissections, therefore, are not attended by those revolting, unpleasant feelings-those compunctious visitings-which render the study of animal physiology so disgusting, particularly when called upon to operate on living subjects.

Let it not be inferred, because the whole mass of inanimate or vegetable life is under the control of man, that power is to be exercised over it without any expenditure of those sympathies which we bestow when animal life is in question-that because the vegetable subject is incapable of complaint or resistance, we are to be divested of all concern for it. Whether plants are injured by casualties or neglect, or are wantonly destroyed, they are as much entitled to our regard as when they are in full health, and contribute to our wants and our pleasures. More refined motives than what result from the mere gratificaVOL. XXI.---No. 41. 15

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tion of sense should influence us in the cultivation of plants. We should take as much pleasure in the health, in the beauty, and in the longevity of a plant, as we do in its usefulness. When we undertake the care of a tree or a flower, it should be our study to protect and relieve it from those evils to which they are liable, with motives distinct from gain.

It is not intended that any mawkish sensibility should be displayed that we are to weep over a faded lily, or moralize over a fallen leaf, or "die of a rose in aromatic pain"-but to feel that a positive duty is neglected when plants are allowed to suffer evils which attention could alleviate, or foresight prevent. To entitle vegetable life to our regard, we should consider it as the work of the same Divine Spirit which created our own. It is this expanded thought which has exalted the study of vegetable physiology to its present high standing in science.

It is to this enlarged and liberal sentiment that we owe the diffusion of knowledge in this generation; and, as we before observed, to none are we so much indebted as to the French philosophers. They are an ingenious, inquisitive, patient, and laborious race, beginning at the very germ, and rendering the study of each particular branch clear and satisfactory. We can follow Dr. Dutrochet and Professor De Candolle, with much pleasure and confidence, throughout their physiological enquiries, because they lead us step by step from the most unpromising beginnings to the broadest and clearest heights, and they only leave us to our own resources when all the rubbish and difficulties have been removed.

The fact is, the French are the best pioneers and experimentalists in the world, and we are absolutely enticed to follow them by the easy mode of explanation that they offer. We have not, as hitherto, to jump over an appalling gap, or to climb up a rugged hill, stumbling as we proceed, before we can obtain a starting place for our speculations. They present us with a smooth road, imperceptible in its ascent, of which we know the termination, having legible milestones for our guides. The French philosophers are, besides, as courteous and considerate when explaining their scientific knowledge as in a ball room. What a Frenchman knows, he is willing to tell all the world, and to tell it in the kindest manner. The Germans are likewise communicative, but not courteous. An Englishman is slow to communicate his discoveries, his first care being to appropriate the benefits to himself. This selfish propensity cannot, however, always be gratified, for his own countrymen are as unwilling to admit his claims, as he is to make them public. He has to fight his way through a host of ill-natured, envious critics, who wear out his time and his patience in the contest; and many a nervous and sensitive person has preferred

to give up the honour and benefit of an important improvement in the arts or in science, rather than run the gantlet to substantiate his claims as the original inventor.

It is with pleasure and profit, therefore, that we study a French author; and Dr. Dutrochet is conspicuous for simplicity and perspicuity, as well as for his honest and considerate attention to the claims of those who have preceded him in his particular studies. Never was there any thing more beautifully clear and satisfactory than his work entitled Anatomical and Physiological Researches-there is nothing equal to it extant.

The Genevan philosopher, M. de Candolle, is likewise entitled to our gratitude, for he has added many new and useful hints. It has been the peculiar happiness of these two distinguished men, to know that they have infused more spirit into the study, and have created a greater eagerness for pursuits of this kind, than any other previous writers on vegetable physiology. Thousands of minds have been set to work-and in the right way, too-they have not only been taught to think for themselves, but have been taught how to set about thinking.

Vegetable physiology, as treated by these gentlemen, is one of the most fascinating and satisfactory studies in the world; and happy must that man account himself, who has leisure and abilities to walk out in the fields and orchards, and look at the wonders which the learning of these philosophers has laid open to him. He who makes this branch of science a study, feels himself at once elevated far above ordinary men. He is entrusted with the key of knowledge, and he can at any moment unlock the door and walk in a world of delights; innocent pleasures of which the ignorant can form no conception.

It is gratifying, likewise, to pursue the same experiments, and with the same results, that were so clearly laid down by these able and ingenious men; but it is still more gratifying to know that our investigations have led to some discoveries that may, ultimately, add new light to this branch of science.

The closest observation, and the clearest view of the subject, prove to us that there are two indisputable points of resemblance between a plant and an animal-vitality and instinct. These two elementary principles are imparted, continued, and extinguished, in the same manner, whether infused in a moving or fixed body. In many other particulars, although a similarity in the physical structure and capacities can be traced, yet the organic material is so very different that there is great danger in being deceived. But in the two grand leading points-vitality and instinct-the same laws govern both plants and animals; vicissitudes of climate, light, shade, moisture, dryness, nourishment, care, neglect, produce the same effect on a tree as on a man. It is partly to ascertain how the internal organs of

each are disposed, and to trace a connection between them, that these minute investigations have been made. What a simplicity there is in all the works of nature, that, with only a variation of the same powers-life, instinct, and matter-build up every thing that lives, and moves, and has a being!

Plants have the instinctive power of motion, and are impelled to it by external as well as internal influences. They have movements peculiar to themselves, either in the search of food, or to protect themselves from injury. This movement is effected by elongating the rootlets, and by folding up the leaves. Such processes, for ever going on, could only result from an irritation or excitement in the system similar to that which takes place in the animal economy. The bird, the bee, and the new-born child, have no more reason to guide them, when they go to the exac tspot for nourishment, than the spongelets of a tree have, which drink in by a similar process-suction-the fluid nutriment that the rootlets and slender filaments place within their reach. They are the arms or feelers, on the surface of which the spongelets are placed; and being placed on the surfaces of all the ramifications of these extremities, they are thus brought into immediate contact with the aliment suited to them.

We are very willing to use the term "nervimotion," as introduced by Dr. Dutrochet, but it appears to us that irritability is quite as suitable as the one proposed. By irritability in the animal system we do not imply any mental perception of sensation, but simply a physical capacity to react on the application of pressure or deleterious stimulus. If a fly and a chicken be suddenly deprived of their head-which part, in the higher order of animal life, is the seat of volition-they still remain susceptible of the same movements, for a certain length of time, to which they were subject when the will could control them. The leg of the spider called long-legs will sometimes keep in motion, while lying flat, for upwards of a quarter of an hour. It imitates the motion of walking exactly as if it was still attached to the body of the spider, and yet in no insect or animal is the ligament and cuticle which connects it with the body so frail and delicate-almost a touch will separate the whole leg, having three joints, from the body.

In consequence of the reproductive principle with which plants are so strongly endowed, and of the remoteness of the extremities from the main radiating point, they are allowed a corresponding quantity of the vital principle. They possess it in greater proportion, and it is of longer continuance in the system, than that which is allowed to animals. There is, likewise, a slower development of this vital energy, which enables a plant the longer to resist the changes of climate, and of those

casualties to which they are the more subject in consequence of being deprived of the powers of speech and locomotion. The reproductive capacity, which plants possess in so remarkable a degree, eminently proves that they have this superabundant quantity of the vital principle.

Each articulation or joint of a plant has the special power assigned to it, not only to receive from the roots its own share of the crude sap as it rises, but of retaining and apportioning this sap to its own use, so as to sustain the particular twig that emanates from this articulation. Of course, when the terminal shoot is separated from the joint there is a reservoir of this cambium or elaborated juice at the base, which is sufficient to sustain the slip until it can strike out roots and support itself.

There is an important fact corroborative of this, which is this-the extremities of the tallest trees exhibit the first appearance of life when excited by the sun's rays in the spring; they show as much animation and vigour after being exposed to the cold of a Siberian winter, as if the general circulation had never been checked. Whereas tortoises, and other animals which lie torpid during the winter, are obliged to draw their limbs within the shell, or curl up their bodies in such a manner as to bring the extremities as closely as possible to vital heat. Plants, therefore, have a power connected with that of divisibility, by which heat is generated at the articulated sections, and this heat is excited even before the frost is out of the ground in the spring.

Although the organic structure of plants varies so much in different species, yet the same phenomena of vitality, instinct, and irritability, exist in all. The circulation of sap is so rapid in the grape vine, owing to the peculiarity of the interstitial medium, that, when wounded, the exhaustion from the copious discharge often endangers the life of the plant. The same effect is produced in seasons of great drought: the grape vine suffers for the want of a constant supply of fluid nutriment; if it be withheld the plant slowly loses its energy, the leaves hang loosely and without motion, and the unripe flaccid berries wither on the vines. Here an analogy can be traced between the animal and plant; but our object is chiefly to speak of vegetation, and not to draw comparisons.

The electric fluid will sometimes prostrate the energies of the grape vine. We have seen the leaves of a whole vineyard hang lifeless after a warm, gentle, July shower, during the hottest period of the day. Many of the vines never recovered from this syncope, if so it may be called. A warm shower in mid-day will sometimes produce the like effect on the sensitive plant, but it always revives after the shower is over.

Every thing that has life is more or less affected by the elec

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