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than animal nerves. An assumption like this is not absolutely necessary. It is impossible to say that certain vegetable organs and tissues only discharge one function; it is perfectly conceivable that they may be endowed with two or more, abstractedly. Who, for example, could witness an oscillatorial filament wriggle itself out of a plate, and move towards the light with an invincible pertinacity, and could feel a doubt that it possessed the instinct that light was good for it; in obedience to which impulse, it was using every effort in its power to reach it? Place by its side a humble animalcule, which, with movements of equal vivacity, dances hither and thither in its native element, and let science put her finger upon the point where sensation ceases on the one side, and some new faculty commences on the other.
"Here are plants folding close their delicate organs from the cold evening air, expanding them again to their genial sunbeam; here are plants shrinking from the drenching rain, or opening to welcome the refreshing shower, as their different constitutions may suggest; here are some casting forcibly off every intruder to the honey cell; here are others, on the contrary, spreading their leafy traps for the capture of such offenders, here are a few abashed and shrinking from the touch; and finally, were St. Vitus's Dance a vegetable malady too, here is one—the Desmodium gyrens—which is decidedly a victim to it.
"Leaving, however, the discussion to another and more befitting arena, we would proceed to indicate that, putting aside the question of the amount of sensation involved in the motions referred to, there are other and even more remarkable points of view from which to contemplate the subject.
"There is a class of poisons which may be shewn to operate purely upon the sensation of animals, causing no chemical or physical disorganisation of their structure ; these are opium, belladonna, Prussic acid, nux vomica, tobacco, &c. If now, it can be shewn that these agents act in a deleterious manner upon plants, we have the presumptive evidence of strong analogy in support of the idea of vegetable sensation. M. Marcet has set the question at rest. From his experience it has been found that, even in minute quantities, the poisons specified are destructive to vegetable life. If a leaf of the sensitive plant is cut off, and placed in pure water, it curls up its leaflets, but in a short time they again expand, and retain their irritability for several days, expanding and shrinking up as on the plant itself, when untouched with the finger or with a needle; but if another leaf is cut off, and placed upon water, to which a solution of belladonna has been added, the leaflets collapse, and subsequently expand; but after this it seems paralysed—its life is extinct, and even if it is then put into pure water, it no longer can be made to contract. Electricity, extreme cold, mineral poisons, arsenic, &c. are productive of similar consequences. Every one is familiar with that simple experimental, the fumigation of a rose-tree, to destroy the insects which infest it. It affords us an instance of the action of a narcotic poison not only upon the insects, but also upon the plant itself. The little creatures tumble from the branches, stupified with the tobacco fumes. And at the same time it may be observed that the leaves of the rose droop, some of its youngest and tenderest branches hanging down, and only recovering, after exposure to a purer atmosphere, their former position and healthy aspect. The effect of these poisons obviously indicates that all plants possess an occult principle, having a certain analogy to sensation. It is found, also, that when certain chemical substances in solution are presented to their roots, the foreign matter is carried into the circulating system of the plant, but is almost invariably, if it is unsuitable for its nutrition or for the formation of its secretions, carried down again, and thrown off by the roots. Even in the selection of its proper food by the delicate spongiole of the root, it would seem as if some kind of discerning faculty were in operation, which at any rate may be compared to animal instinct.
The struggle which plants growing in a cellar or darkened room make towards the light, however small the glimmer which may pierce the darkness, and the sedulous manner in which the radicle and plumule of the germ respectively avoid and seek the same influence, seem to speak in similar language. Every one who has watched the growth of the tendril of the vine, or the stem of the creeping-plant, must have observed that neither make any turns until they come into contact with some object around which they can twine ; so that, up to a certain point, the stem of the most inveteratcly-twisting plant remains as straight as possible; but at the point of contact with another body, a volution immediately commences, and thenceforward it proceeds in a spiral direction around the object held in its embrace. In the case of the briony, simple contact with the object is not sufficient to cause the twisting of the stem. To prove this, the experiment of tying it with a string at a certain point has been made; but the plant made no attempt to twist at that point. A small weight was then attached to the string, and the tendril immediately began to shorten itself by making several spiral turns. This seems to indicate that the tendril of the briony, naturally, will twist only when it has the weight of the stem to support. The writer who records this experiment, and whose striking phraseology is almost indicative of his name, adds, ' it is a hand seeking in the dark, and grasping what it has felt by the action of muscles remote from the sensible point.'
"The remarkable manner in which plants search for their food, within certain limits comparable to that of animals, appears to imply the existence of some higher impulse than mere fortuity. The strawberry plant will thrust its ' runners' completely across a garden walk, on to a bed of soil on the opposite side, where it will for the first time, as it were, perceiving its object to be gained, push out roots, and form a new plant. It is not uncommon to find travellers relating the most singular freaks played by trees and plants in quest of nutriment. Trees are sometimes found which have taken root on one side of a deep ravine, and having exhausted the sterile soil on that side, have pushed forth roots completely across the abyss, which have gained its opposite side, and there struck deep into more fertile ground. Plants are often to lie found which have rooted in old walls; but soon experiencing the want of soil, extend long roots in the direction of the ground, which they penetrate, and then form radicles. If the roots of a plant are accidentally denuded, and there happens to be some moist substance, as wet moss, in their neighbourhood, they direct themselves towards it, and eventually succeed in reaching it."
CYTISUS LABURNUM-COMMON LABURNUM.
Class XVII. DIADELPHIA. Order III. DECANDRIA.
Natural Order, LEGUMINOS^E. THE PEA TRIBE.
Laburnum, (a name formed from the Alpine name of the tree L'Auhours.) Calyx campanulate. Legume many.-seeded, not dilated at the upper suture. Flowers yellow. Branches unarmed, leafy. Branches terete, whitish: leaves petiolate: leaflets ovate-lanceolate, pubescent beneath: racemes pendulous, simple: pedicels and calyxes clothed with adpressed pubescence: legume linear, many-seeded, clothed with adpressed pubescence. Native of Europe, frequent on the lower mountains. The laburnum, often called golden blossoms by country people, is a tree dear to the child at school, because its pendant clusters unfold just before the Midsummer vacation, and whose opening buds have erewhile made the young hearts within us beat with joy and hope.
"The Laburnum is a large growing tree, and although," says Gilpin in his Forest Scenery, " we have not frequently seen it assume that character which would make its form an object of desire for the artist, yet its rich leguminous golden flowers give it great value for the pleasure ground. It is, moreover, a hardy tree, and we can answer, from our own experience, that the timber, when made into chairs and other pieces of furniture, and allowed to darken, is sometimes hardly distinguishable from rosewood. If not allowed to get dark, the outer wood remains of a delicate yellow; the heart wood is always of a deep hue. It is extremelv hard, and so heavy, that it will sink in water; and the French, who make great use of it, call it the Ebony of the Alps, because it is a native of the valleys of these mountains. The timber of this tree is indeed the highest in price of any that grows in Britain. A considerable quantity of laburnum was sold by public sale at Brechin Castle and Panmure, in 1809, at fully half a guinea per foot. The tree is very abundant in that neighbourhood, the roads being often bordered with it. There is a shrub variety of the laburnum, which, in its department is no less beautiful. The true sort is easily distinguished from the shrub by the greater size of the leaves, and the superior length of the bunches of papilionaceous flowers.
A laburnuu^ which was cut at Greenlaw in Edinburghshire, in the year 1763, measured four feet six inches in girth, and furnished a plank of beautiful red wood fourteen inches broad. It was planted in the end of the seventeenth century, when laburnum trees were first introduced into Scotland. We are persuaded that many much larger laburnums now exist in the country.
The shrubby stems of C. Scoparius are sought after, on account of their beauty when cut into veneers. Goats are fond of browsing on the herbaceous twigs of this plant, which is believed to be the flowermg Cytisus of Virgil; and its branches, when young and tender, are often used in this country as well as in Italy, as fodder, and sometimes substituted, on account of their bitterness, for hops in brewing. They are also said to be capable of tanning leather, and of being made into a coarse kind of cloth. In our provinces, the older plants are frequently employed as thatching for cottages, sheds, and ricks. The seeds have a very bitter taste, and, as well as a decoction of the young twigs, called "broomtops," are esteemed as a diuretic. When burned they afford a considerable quantity of vegetable alkali, upon which their medicinal properties chiefly depend; but their bitterness is also, in dropsical habits, where strength is in general greatly reduced, a further recommendation.
The seeds of the common Laburnum (C. Laburnum,) were observed by Haller to be violently emetic and cathartic; but they are now known to be absolutely poisonous. Several serious cases have occurred, both in this country and in France, from children swallowing laburnum flowers and seeds. ,
Professor Taylor (in his work on Poisons, p. 759) tells us that "Dr. Traill met with two cases of poisoning by the seeds, and an interesting case, which was the subject of a trial at Inverness, has been more recently reported by Dr. Christison. (Ed. Med. and S. J. Oct. 1843.) A youth, with the intention of merelyproducing vomiting in one of his fellow-servants, a female, put some dry laburnum-bark into the broth which was being prepared for their dinner. The cook, who remarked a "strong peculiar taste" in the broth, soon became very ill, and in five minutes was attacked with violent vomiting. The account of the symptoms is imperfect; for the cause of them was not even suspected until six months afterwards. The vomiting continued thirty-six hours; was accompanied by shivering,—pain in the abdomen, especially in the stomach,—and great feebleness, with severe purging. These symptoms continued, more or less, for a period of eight months; and she fell off in flesh and strength. At this period she was seen by a physician, who had been called on by the law authorities to investigate the case. She was then suffering from gastro-intestinal irritation, vomiting after food, pain in the abdomen, increased by pressure, diarrhoea, tenesr mus, &c., with other serious symptoms. The medical opinion was that she was then in a highly dangerous state. The woman did not eventually recover until the following April. There was no doubt, from the investigation made by Dr. Ross and Dr. Christison, that her protracted illness was really due to the effects of the laburnum-bark.
"Some experiments were then made on the action of the poison on animals. A teaspoonful of the powder of dry laburnum-bark was administered to a cat. Soon afterwards it writhed, apparently in great pain; in a short time it vomited violently, and, although languid and dejected for the rest of the day, it quickly recovered. Sixty-nine grains of the same powder were given to a dog. In ten minutes it whined and moaned, vomited violently, and soon got well. On a second occasion, twenty grains were found to act as a powerful emetic upon the animal. An ounce of the infusion of laburnum-bark, containing the active matter of sixty-two grains, was introduced by a catheter into the stomach of a full-grown rabbit. In ten minutes the animal looked quickly from one side to the other, twitched back its head twice or thrice, and instantly fell on its side in violent tetanic convulsions, with alternating emprosthotonos and opisthotonos, so energetic, that its body bounded with great force upon the side, up and down the room. Suddenly, however, all movement ceased, respiration was at an end, the whole of the muscles became quite flaccid, no sign of sensation could be elicited, and the animal died within two minutes and a half after the poison was injected into the stomach. The body was opened in two minutes more, and the heart was found gorged with blood, but contracting with some force. The stomach was filled with green pulp, soaked with the infusion. No morbid appearance was visible anywhere. In repeating this experiment, one rabbit died in half an hour, another in three quarters of an hour, after small doses of the infusion were injected into the stomach; and a third rabbit speedily died after eating greens merely impregnated with the infusion. In all these instances convulsions were the leading symptoms produced. The same effects are popularly ascribed to the leaves, young pods, and seeds of the tree; but no experiments have been performed with these. The facts here detailed show that laburnum-bark is a most energetic poison—as powerful, even, as nux vomica.
"Analysis.—There are no chemical means of detecting the nature of this poison, especially when administered in powder or infusion; or when a decoction of the bark is given in food. A decoction of the bark yielded a clear light brown infusion with a slight acid reaction. It was not precipitated by albumen, or a solution of tartarized antimony; hence it contained no tannic acid. With a persalt of iron it acquired a dark greenish-brown colour,—of a deep red by transmitted light. Strong nitric acid caused it to acquire a lighter colour. It gave a very copious gelatinous precipitate with acetate of lead, which was almost entirely re-dissolved by acetic acid. On decomposing this precipitate by sulphuric acid, filtering and applying a persalt of iron to the filtered liquid, a greenish-brown precipitate fell (gallate of iron) without any red tint whatever. A much stronger decoction of the bark, as well as a decoction of the tops, yielded similar results.
"The bark has been said to contain meconic acid; but these results prove that none of this peculiar acid is present. The only plan for determining with certainty the deleterious properties of the substance, would be by exhibiting a portion of the suspected decoction or infusion to animals.
"It has been recently announced that meconic acid is actually contained in the bark of the common laburnum tree, and that the iron-test strikes, with a decoction or infusion of this bark, a deep red colour, characteristic of meconic acid. The writer has further asserted that in testing for meconic acid, laburnum and laudanum would give precisely similar results. The improbability of laburnum bark or its decoction being found in the stomach, unless it had been intentionally administered as a poison, would be sufficient to take away the practical force of this objection, admitting it to be valid.
"Laburnum is a most powerful poison, and destroys life under symptoms widely different from those produced by opium; but the result of many experiments with the concentrated and diluted decoction and infusion of the bark procured in the metropolis as well as at a distance in the country, is that I have not been able to detect in it the slightest trace of meconic acid, or of any acid that could possibly be mistaken for it. The iron-test gives at first a deep reddish colour when added to the decoction, but this colour speedily changes to a dingy greenish-brown, instead of remaining of a clear red like the meconate of iron. It is quite certain that a person used to the analysis of opium could not mistake this chemical change for that produced by meconic acid. As tannic acid gives no precipitate with the decoction, the effect is probably due to gallic acid combined or mixed with organic matter. The clear liquid obtained from a decomposition (by sulphuric acid) of the precipitate formed in the decoction by a salt of lead, did not acquire any red colour upon the addition of the iron-test.
The deleterious properties of this plant (says Professor Burnett,) depend upon a peculiar proximate principle, discovered by MM. Chevalier and Lassaigne, and called by them Cytisine; small doses of it, when given to various animals, produce vomiting, convulsions, and death. The same principle, or a very similar one, appears to be present in the flowers of Arnica montana, (the Leopard's bane;) and in Asarum Europeum, (the Asarabacca.) Notwithstanding the poisonous quality of the seeds, and the purgative effects of the young shoots, the latter form a very favourite food with hares and rabbits, who, it is said, will touch no other plant while a twig of laburnum remains; and hence it is frequently sown in plantations to protect young trees, until they are large enough to resist all leporine assaults.