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I hold to be strokes of ELECTRICITY: and I owe you picking of a crow," good Mr. Loudon, for refusing, some time ago, the admission of a gentleman's Essay on Electricity, averring it incompatible with Natural History; when you very well know that no part of organised nature can go on a moment without it, and that no part of inorganised matter* exists, not subject to its pervasive influence.

A very considerable portion of those volleyed lightnings and rolling" thunder, that deep and dreadful organ-pipe," which often keep such awful coil and "pother o'er our heads," has frequently very little or nothing to do with us; for though a nimbus be heavily discharging its rain, cumuli are bagged up in different heights the lobed and thin edges of which may be often seen through the shower, tinged by the flash; as one cloud is giving or receiving the fluid, according as it is more or less disposed. This may be proved by theory: but I have very often witnessed it, safely seated on the tops of very high mountains, in the calm and quiet sunshine and sweet serenity of a blue sky: and some who read this article will remember witnessing it with me on the craggy heights of the Glissegs, and even from so low an elevation as the Balder-stone of the Wrekin. But when a column of electric fluid affects the earth, either ascending or descending (for I confidently contend, in the very face of some modern theorists, that it ascends innumerously oftener than it descends, though I must not pause to prove it here), it scorches the ground all around its edge, where there is plenty of oxygen in contact with it, and leaves the centre unscathed, where the oxygen is either expelled or destroyed, and so fertilises the extremity: the consequence is, that the first year the grass is destroyed, and the ring appears bare and brown; but the second year, the grass resprings with highly increased vigour and verdure, together with fungi, whose dormant seeds are so brought into vegetation, that without this exciting cause might have slept inert for centuries. These fungi are most generally of the Agaricus, Bolètus, or Lycopérdon, sometimes Clavària, genus; I have very rarely seen any other. The fertilisation of combustion, as agriculturists well know, though violent, being of short duration, these circles soon disappear. They are, moreover, generally found in open places, on hill-sides, wide fields, and broad meadows, where lightning is more likely to strike; and seldom near trees or woods, which throw off, or receive

Excepting glass, and a very few others similar; to which, however, it may be most easily communicated by the intervention of metal, and made to retain it perfectly when the metal is removed.

the fluid silently and imperceptibly. I have indeed sometimes seen one all round a tree, which must have been by a stroke, from which trees are by no means exempt. I confess I have never been able to produce a single spot by electricity: though a learned friend and myself one summer collected and repeatedly discharged a prodigious accumulation of battery on the grass-plot before my dining-room window: but it requires, to produce a very small ring, an incalculably larger column than it is in the utmost power of man to accumulate or discharge. The following year, however, my friend was pleasingly amazed at beholding a noble fairy ring on the very spot! and was long in doubting suspense, till I informed him I had made it with what really acted on the same principles, fresh soot.

I remember (though for relating it "I may chance have some odd quirks and remnants of wit broken on me"), when a youth at Christ-church, some Oxford wags traced with gunpowder, and fired on the short-mown grass of the Grand Quadrangle in that College, in large capitals, the short monosyllable that so much appears to puzzle poor Malvolio in the epistle forged by his Mistress Olivia's chambermaid; and to the affected indignation of the old dons, and the titillatory fun of the merry Oxonians, the little word flourished there in brown and green for two years; and may be still talked of yet in those frolicksome regions, by such humourists as, Sir, yours,

Westfelton, near Shrewsbury,

Dec. 30. 1831.

JOHN F. M. DOVASTON.

ART. II. An Essay on the Analogy between the Structure and Functions of Vegetables and Animals. By WILLIAM GORDON, Esq., Surgeon, Welton, near Hull. Read before the Hull Literary and Philosophical Society, Nov. 19. 1830. Communicated by Mr. GORDON.

(Continued from p. 30.)

HAVING now given this brief outline of the nervous system, I shall proceed to prove that there is a structure very analogous to it in plants. In the first place, the most superficial observer cannot but have perceived the great similitude that there is between the pith of vegetables and the spinal cord of animals. They are both surrounded by a membranous covering; they are in every way carefully protected from injury; and they both send off branches in a manner precisely analo

gous: the pith gives off its medullary rays, which are distributed over every part of the plant, exactly in the same way as the spinal cord gives off the nerves, and diffuses them through the animal body. In the second place, phytologists have discovered that the pith contains within its cells a number of globular bodies, resembling nervous ganglia. The number of these nervous globules bears a close proportion to the quantity of pith. Their size and number differ very much in different plants, and in the same plants at different stages of their growth. In the third place, the pith is most abundant, and the globular corpuscles found in it are the most numerous, in plants which are young and growing; the period when vegetable life is in a state of its greatest vigour. So, in infancy, when the increase of the body is most rapid, the nervous system is proportionally larger than in adult age. The brain, at birth, forms the sixth part of the whole body; but in full-grown man it forms only the thirty-fifth part. Some have supposed that the pith is essential to the production of the fruit; some, that it promotes the circulation of the sap; and others, that it supplies the leaves with moisture for exhalation. These opinions, however, have not been established by facts. Indeed, from the circumstances which I have mentioned, there can be little doubt that the pith performs functions very similar to, if not identical with, those of the nervous system. It appears that the one, as well as the other, is the source of vital action: for we find them both presenting the same form, the same arrangement, and the same distribution; and we observe them both exhibiting the greatest magnitude when the functions of growth and nutrition are the most actively exercised, and when the vital power, upon which these functions depend, is required to act with the greatest energy. The other proofs of the existence of a nervous system in plants I have drawn from the effects produced upon them by certain poisonous agents, and also from their capability of preserving a certain degree of temperature under a great variety of circumstances. Most persons are acquainted with the deleterious effects which prussic acid, belladonna, nux vomica, and similar substances are capable of exerting upon the animal frame. If a large dose of prussic acid be administered to an animal, it produces death in the course of a few minutes. If a less quantity be given, it occasions loss of sensibility, and other alarming symptoms. Results similar to these are observed to take place in plants exposed to the influence of prussic acid. For instance, if concentrated prussic acid be dropped upon a plant, it speedily destroys its life; but if the diluted acid be em

ployed, its application is followed only by impaired irritability. Again, if a strong dose of the infusion of belladonna be given to a man, it occasions vertigo, sickness, convulsions, paralysis, and death; if the same infusion be poured over a plant, the leaves become affected with a sort of spasmodic action: they then grow flaccid, and in the space of a few hours the plant dies. Now, it has been long known that the poisonous agents which I have named do not operate injuriously upon the animal body by destroying its fibre, but by interrupting the functions of the nervous system. It therefore seems pretty evident that, since they act in the same manner on vegetables as they act on animals, the former must, like the latter, be endowed with nervous structure. It has been a question among physiologists to determine in what manner poisonous bodies produce their specific effects upon the animal system. On this point several opinions have been advanced. Majendie came to the conclusion that they were absorbed by the veins, and passed directly into the circulation. Brodie supposed that they sometimes operated by entering the circulation, and at others by acting on the sentient extremities of the nerves, and, through them, on the brain. There are others, again, who imagine that they indirectly enter the circulation by absorption through the lymphatics, but that, before they can exert their specific effects upon the general system, they must be brought into absolute contact with the brain. Morgan and Addison, in an essay published about fifteen months ago, argue that all fair analogy forbids the conclusion, that at one time a poison shall be taken up by the veins, and carried through the circulation to the brain, before it produces any sensible effect; that at another time the absorbent vessels shall take up the substance, and, by their communication with the subclavian veins, be thus instrumental in carrying the specific agent into the circulation, and thence to the brain; and again, at another time, the impression made upon the extremities of the nerves of the poisoned part shall at once, by the medium of those poisoned nerves, be conveyed to the brain, independently of absorption either by the veins or absorbent vessels. . . . As reasonably," say they, "might it be presumed, that at one time the sense of taste was communicated by a branch of the fifth pair of nerves, and at another time by the salivary ducts, as to entertain a belief that veins, absorbents, and nerves individually performed a function of precisely a similar nature." These gentlemen, therefore, after performing many scientific experiments, conclude, and apparently with great correctness, that all poisonous agents produce their

specific effects upon the brain and general system through the sentient extremities of the nerves, and through these only; and that, when introduced into the current of circulation in any way, their effects result from the impression made upon the sensible structure of the blood-vessels, and not from their direct application to the brain itself. Since, then, it is proved, that certain poisons can act upon the animal body in no other way than by affecting the functions of the nervous system; and since it is further proved that they occasion their specific effects upon the general frame through the medium of the nerves, and through these alone; and since these poisonous agents produce the same injurious effects upon vegetables that they produce upon animals; I think we have a right to infer that plants not only possess a nervous system, but that they possess one very much resembling that which exists in the animal body. Again, it is well known that both plants and animals have the faculty of preserving a certain degree of temperature, let that of the medium in which they are placed be what it may. For instance, the temperature of the interior of the stem of a tree will seldom sink below 56°, although that of the atmosphere be not higher than 20°. The human body never has its temperature reduced below 98° or 96°, not even if surrounded by an atmosphere cold enough to effect the freezing of quicksilver. Now, there can be no doubt that the heat of vegetables is produced, in a great measure, by various chemical processes going on within their different organs: yet it is very clear that it must arise also from other causes; for it continues to be generated, though in a less degree, even in winter, when every chemical action within the plant is almost entirely suspended. Some have supposed that at this season it is transmitted, through the roots, from the earth in which the plant is growing. But if this were true, how does it come to pass that we sometimes find the water immediately surrounding the roots and their spongioles in a frozen state, while that within them and within the stem is quite fluid? and how comes it to pass that plants situated on the side of rocks, whose roots, from the deficiency of soil, are almost as much exposed as their branches, possess as much warmth within the interior of their stem, when the thermometer stands at 30° below zero, as those whose roots are deeply buried in the earth? Animal heat, like that of plants, likewise depends very much upon a chemical process, viz. the combination of the oxygen of the air with the carbon of the blood, forming carbonic acid. It is not, however, derived entirely from this source. The experiments of Brodie and of Sir E. Home show that it is to a considerable extent

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