Electricity

ELECTRICITY. This is one of the most important and potent forces in nature, and especially interesting to the agriculturist, now that it is known to be a valuable factor in the growth of plants, and also in its various action in the phenomena of nature as affecting rainfall, the formation of hail, its influence in tornadoes .and various other meteorological phenomena hitherto unsuspected and even yet not well understood. The influence of electricity on vegetation and the internal electricity of vege tables are two of the most interesting of the -subjects connected with electricity, and the following data in relation to the influence of electricity, compiled from various sources, show that the causes which liberate electricity in organized bodies under the reign of life, or a little after it, are of three orders, physical, chemical, and organic, the latter belonging to certain vital functions not clearly defined. There exists in vegetables an ascending sap and a cortical sap, the latter not having the same composition as the former and, according to some physiologists, having a descending motion. Both are separated by tissues, and produce electric effects like those of a pair of galvanic plates. These effects are so much the more remarkable, as they relate to the formation of the bark and that of the wood. The parenchyma, which is analogous to the pith, occupies the circumference of the bark, while the pith itself is found at the center of the ligneous system. This inversion responds to reverse electric effects. Each stem or branch being composed of an interrupted series of heterogene ous concentric layers, their successive contact gives rise to electric effects rising from the heterogeneous liquids moistening these layers. The ascent of the sap is not only due to endos mosis and to capillary attraction, but also to the presence of buds, which draw from the stem and branches the substance for their development. The buds afterward are not slow in forming leaves, which become the seat of a continual evaporation, which concurs with the ascending motion of the sap, and influences the manifesta tion of electric effects. After the discovery of voltaic electricity, Dr. Baccomio undertook to construct piles with organic matter of vegetable origin, as Mettencei has since done with portions of the muscles of different animals. lie first experiments, however, had no value. Becquerel, Wartmann, and Donn6, by means of metallic plates or wires in connection with a multiplier, obtained currents in vegetables and fruits. The existence of electric currents constantly circulat ing in vegetables, and between them and the earth, is manifested not only in the direct experi ments which have been made, but according to the following physical considerations • In the vertical section of a stem, the ascending sap, before its entrance into the vegetable by the roots, is composed of water, holding in solution air, carbonic acid gas, and very small quantities of saline and organic matter removed from the soil. As to the parenchymous sap elaborated in the leaves, it loses insensibly a portion of its constituent parts for nutrition. Both saps are found in the conditions requisite to form contacts by insensible transitions, and consequently to produce electric currents without the interven tion of metallic plates. On the other side, the earth being in direct and permanent communica tion with vegetables, through the medium of the roots, participates in their electric state, result ing from the diverse elaborations which take place in their tissues, just as we have seen atmospheric temperature influence the heat of vegetables. From 'very delicate experiments, confirmed by Riess, Ponillet concludes that the action of vegetables upon the oxygen of the air is one of the most permanent and powerful causes of atmospheric electricity. A gram of pure carbon, in changing to the condition of carbonic acid, liberates electricity enough to charge a Leyden jar. Now the carbon entering into the constitution of vegetables cannot give less electricity than freely burning carbon ; hence we may conclude, that upon a surface of vege tation of one hundred square meters, (0.099 rood) more negative electricity is produced in a day than would suffice to charge the strongest electric battery. Buff took up the experiments of his 'predecessors, without putting platinum plates in direct contact with the organs of vege tables, and operating much as Dubois Reymond has done in his researches on animal electricity. In order to change as little as possible the natural conditions in which a plant is found, Buff employed water as the medium of communica tion between different parts of the plant and the galvanometer. He first compared the electric state of the leaves with that of the roots. He then examined branches separated from the vegetable; afterward the young and fresh bark, the buds, flowers, etc. He regards it as estab lished by his experiments, that the roots, and all the external parts of plants which are filled with the juices of vegetation, are negative relatively to the surface, more or less moist, of the leaves, the flowers, the fruits, and the young branches. Buff thus explains this fact : The interior of the plant contains various juices, which can not pass through the epidermis, while the exterior moist ure always soaks a little into this membrane. We have then in contact a membrane soaked with water, and vegetable organs charged with liquids of various natures. If, now, we establish between this membrane and these organs a closed circuit, a current must evidently be produced. But it appears evident, adds Buff, that this current has a relation, very indirect and remote, to the phe nomena of vegetation. Becquerel reaches these conclusions. Derived currents are produced in the stems of vegetables by platinum needles, one introduced into the bark, the other into the wood, directed from the parenchyma to the pith. Similar currents are produced in the bark, proceeding from the cambium to the paren chyma, directed inversely to the preceding. sap, or the liquid of the cortical parenchyma, if retained in contact with the air for a few seconds, suffers such a modification that on putting it anew in contact with sitp found in the green part of the parenchyma of bark it becomes nega tive to it. Derived terrestrial currents are pro duced through the medium of the roots, of the pith, and of other parts of the stem. The direction of the terrestrial currents shows that in the act of vegetation the earth constantly takes an excess of positive electricity, and the paren chyma of the bark and of the leaves an excess of negative electricity, which is transmitted to the air by the exhaled water. The distribution of the ascending juices and of those of the cortical par enchyma warrants us in believing that currents circulate constantly in vegetables, directed from the bark to the pith, passing through the roots and the earth, or perhaps without passing through them. Chemical actions are the primary causes (it cannot be doubted) of the electric effects observed in vegetables. These effects are varied, and up to the present time we have been able only to observe a small number of cases. The opposite electric states of vegetables and the earth give rise to the thought that by reason of the power of vegetation upon continents and islands they may exert a certain influence upon the electric phenomena of the atmosphere. So Becquerel and Wartman believe that closed cur rents constantly circulate in the interior of each plant, which are directed from the bark to the pith, and thence to the extreme branches; they the production of these currents to thepresence of two different liquids reacting chemi cally upon each other by the intervention of tissues that are scarcely permeable. De la Rive remarks that it seems demonstrated that hitherto, we have no proof of an electric state in living vegetables analogous to that which we have found in the muscles and .nerves of animals; and that all the traces of electricity that have been collected may be attributed to ordinary chemical, reactions, and in some cases to atmospheric elec tricity. The phenomena of the osmotic force lately studied by Graham, are not contrary to. this conclusion, since it is to a chemical action that he attributes the production of the electricity that accompanies endosmosis. A curious experi ment made by Donne is as follows: He found in apples and pears an electric current passing from the stem to the eye, making the stem end electro negative and alkaline, while the end of the eye is electropositive and acid. The peach, apricot, and plum present a reverse current. In the plane perpendicular to that which' passes through the stem and the eye, the electric current ceases at equal distances from the centre of the fruit. The juice of these fruits has the the same electric properties. Donne thinks that these effects are not due to the acid and the alkaline quality of the fruit, hut that all the juice of fruits is not of the same composition at the stem and the eye, and this is sufficiently heterogeneous to produce these electric currents. When an apple or pear is cut in two, the stem end will be found the sweeter, while in the peach or apricot the eye is the best. On the action of electricity on the germination and growth of plants, we find that the earliest experiments seem to have been made by Dr. Maimbray, of Edinburgh, in the autumn of 1746. He electrified two myrtles, and found that they put forth small branches some inches. in length, and even came into blossom during the month of October. This did not happen to. myrtles not electrified, and he attributed the phenomenon to the influence of electricity. This experiment was repeated in Switzerland, France, Germany, and Italy. In the preceding year, 1745, Boze had observed that water issuing from a vessel in minute drops would pour out in a con tinuous stream when the vessel was electrified. The cause of this phenomenon was by L'Abb.1 Nollet, who thought that this electrical effect in capillary glass tubes might have some connection with the sap in plants, and hence pro duce the unusual growth observed by Maimbray. His first experiments were made on fruits, green plants, and moist sponges, and he invariably found that evaporation had been hastened by the action of electricity. In October, 1747, be took two small wooden bowls, filled with the same kind of earth, sowed them with similar mustard seed, and found that after two days several of the seeds in the electrified bowl had come up, while no alteration had taken place in the other. The following day nine of the elec trified seeds had come up—none of the non-elec trified ones; and this superiority was kept up till the plants in the first bowl were ten inches high, and those in the second not more than a quarter of an inch. In repeating this experiment, in different ways and with other seeds, the same results were always obtained. The electrified_ plants, however, appeared rather weaker than those which had not been so treated. In the .same year (1747) John Browning read a paper efore the Royal Society of London, on the effects of electricity on vegetables. In this paper he describes his own experiments as well as those of Baker, who electrified a myrtle at the Duke of Montague's, in Ditton. In the months of April and May, 1747, Jallabert elec trified various plants two hours every day regu larly, exposing them to the open air after the .operation, and found that all of them, and in particular a carnation, grew rapidly and flour ished remarkably. In the autumn of 1747 he

electrified bulbs of hyacinth, jonquil, and nar -eissus, which were beginning to grow in glasses -of water. Those which were electrified grew more rapidly, the leaves were larger and the flowers opened sooner than those not electrified. He found that the electrified bulbs gave off more moisture in a given time than other plants. He :also repeated the experiments of Nollet on mus tard and cress, with similar results, and attrib uted these effects to an acceleration of the move ment of the sap caused by electricity, analogous to that observed by Boze in capillary tithes. Boze, of Wittemberg, electrified, in 1747, dif ferent kinds of plants and shrubs, the growth of which invariably seemed to be accelerated. Sim ilar results were obtained in 1748 by L'Abbe Slenon, of Angers, who, in a letter to Reaumur, :states that, by the aid of electricity, he had greatly facilitated the growth of offsets of ran unculus, even in the depth of winter. In 1752, J. Freke, in his curious treatise on the nature and properties of fire, quotes experiments with electricity on the leaves of the sensitive plant, the irritability of which was then considered by many of electrical origin. In 1771, Nuneberg, -of Stuttgard, took two boxes, each containing five bulbs in all respects alike, and electrified one of them; the plants grew far more rapidly than those in the other box, the relative size after eight days being as eight to five. In the same year, Sigaud de la Fond, of Montpellier, found the bulbs of hyacinths when electrified grew faster and formed more healthy plants than those not electrified. In 1776, L'Abbe Bertholon made some experiments on the con ducting power of plants for electricity, in which he showed the great difference which exists between different plants, those, generally speak ing, being the best conductors which were the most succulent or contained the largest quantity -of moisture. The announcement was made, in 1775, by C. H. Koestlin, that negative electricity was detrimental to vegetation, both animal and vegetable life being retarded by it. This appears to be the first distinct observation as to the different influences of positive and negative -electricity, for the preceding experiments seem to have been made with positive electricity .alone. According to Gasc, Linnaeus proved the influence of on plants. In 1779, a naturalist in London determined to repeat the original experiment of Dr. Maimbray, and accordingly electrified a myrtle for many hours a day for some time in the middle of December. The result was that the tree formed buds and threw out small branches in a remarkable man ner. In 1781, Count de LacCpede describes some -experiments which he had made on vegetables, obServing that invariably in electrifying a plant lie found it grow or increase with more vigor than usual, and that the germination of seeds and sprouting of bulbs placed in water was always hastened in a very decided manner by electricity. Dr. Slarat described in 1782 some experiments he had made on the germination of electrified seeds, from which lie draws the con clusion that it exerts powerful influence on the fertility of the soil. On the seventh day the plants began to make their appearance in the electrified vessels, and at the end of a fortnight they were as forward as similar plants sown on the same day, but kept in a room nine degrees above the freezing point. In the three vessels which were not electrified the seeds had not begun to germinate. In 1783, L'Abbe Bertholon published the first book on electricity applied to vegetables, after making numerous experiments. The results of Nollet and Jallabert were con firmed by Bertholon. He observed that inter rupted electrification appeared to have more influence than when continued, in accelerating vegetation,. He gives some curious facts on the colors, odors, and taste of fruit and flowers, on the development of which be thinks that elec tricity exerts a very remarkable influence. Fruits nearly ripe, on being electrified, were found to acquire the odor and taste of ripeness sooner than others not electrified. Flowers or plants just coming into blossom arrived sooner at per fection, and the colors were more brilliant than is ordinarily the case. When plants in flower were electrified, the blossoms were observed to become more brilliant in color, and of a richer and more delicate tint, than other flowers of the same kind. All these experiments were made with positive electricity, lint with negative electricity the effects for the most part were reversed; germination was retarded, the growth and formation of the leaves were checked, the development of fruit and flowers, and the secre tion of coloring and odorous matters was impe ded. He states that these effects may be observed by experiments on a small scale as well as by carefully watching the electric condition of the atmosphere on a large scale. Bertholon attrib utes the increase and development of certain insects which feed on plants to the agency of electricity, which he says exerts the same influ ence upon them as on the seeds of plants. He accordingly proposes to kill them by an excess of electricity, passing the shocks of Leyden jars through the trunks of trees on which the larvm are deposited, and provided the shock is not too powerful the tree will not be injured. All the ordinary diseases to which plants are subject may, he thinks, be diminished, counteracted, or entirely cured by judicious use of electricity. In 1784, Achard published his observations, in several essays, on the electricity of rain, snow, and hail, on electrifying fluids, on germination, and the influence of electricity on the growth of vegetables, in which he confirms the results of preceding philosophers; also, on the influence of electricity in promoting the fermentation and putrefaction of vegetable and animal matters. He found both negative and positive electricity accelerated the putrefaction of animal matter, causing barley and other fermentable substances to pass into spirit with increased rapidity. From 1786 to 1790 Perzieret made numerous experi ments on chervil, wheat, beans, rye, peas, mus tard, radish, lettuce, trefoil, etc., and in nearly all cases the electrified plants came up first, grew larger, and had longer roots than the others; the leaves were more numerous, larger, and of a decidedly more beautiful green. In 1788, Car moy described iL variety of experiments on the germination of wheat taken from the same ear. After twenty-three days the young plants were measured, when it was found that the unelectri fied had grown eleven inches ten lines, the posi tive eighteen inches five lines, and the negative nineteen inches nine lines. A number of other experiments of the same kind are given, the gen eral result of which is that electricity appears to accelerate germination, negative electricity being more powerful than positive. In 1789, L'Abbe d'Ormoy electrified mustard seed and lettuce for several days in moist earth, and found their ger mination always accelerated. He found also that electrified seeds had always the start of the non electrified, and so beneficial did he find it to ger mination that even old and dry seeds, which seemed spoiled and would not germinate, did so rapidly when previously electrified for some hours. Almost the same results werC published by Berth°lon at nearly the same time. He inclosed parcels of seeds in tin-foil, and kept them con stantly electrified for some days before sowing, when he found that they germinated remarkably soon. These experiments were made with seeds of spinach, endive, and turnip. He describes experiments in which he found seeds to germin ate sooner when placed on the plate of a charged electrophorus. At the end of the last century, the discovery of voltaic electricity, and the brill iant results to which it led, completely eclipsed the hitherto favorite study of frictional electricity. Bozi6res, one of the first, entered this new field of investigation by two papers containing numerous experiments made from 1786 to 1790, in chervil, wheat, beans, rye, peas, mustard, radish, lettuce. trefoil, etc., the result of which was that, in nearly all cases, the electrified plants came up first grew larger and had longer roots than the others. The leaves were more ntimerous, larger, and more beautifully green. These researches confirm the original experiments of Nollet and Jallabert, and prove that the views of Ingenhousz were incor rect, and the effects in question were not results of imperfect experiments, clue to the unequal influence of light, but were really caused by elec tricity. In this view Boziires was borne out by the experiments of Bilsborrow in 1797, who found germination decidedly accelerated• by positive electricity, and still more by negative. In 1807, Sir Humphry Davy published some interesting experiments on seeds and growing vegetables. Seeds placed in pure water at the positive pole of a voltaic circuit germinated much more rapidly than under ordinary circumstances, but at the negative pole they did not sprout at all. He remarks that without supposing any peculiar effects from the different electricities, this may be accounted for by the saturation of the water near the positive metallic surface with oxygen, and that near the negative pole with hydrogen, though he does not think it impossible that the same effect may be due to electricity. When growing plants were made the medium between the two poles of the battery, in one case a mint plant was killed, but another, after ten minutes, remained uninjured. Lime and fixed alkali were found at the negative pole, while chlorine and sulphuric acid were at the positive pole of the battery. These experiments were held by Du Petit Thouars as evidence of the great influence of electricity on vegetation. He held that plants: contained two different galvanic arrangements- one acting vertically through the woody fibres, the other horizontally, through the medullary rays. To these opposite independent currents her attributed the principal phenomena of vegetation. Many experiments on the influence of electricity of low tension on germination have been made by Becquerel since 1833. Seeds in contact with the• upper element of a feeble galvanic current grew faster, while those in contact with the zinc ele ment grew less rapidly than similar seeds planted in glass; the negative extremity increasing, the positive retarding germination. Similar results. were obtained with bulbs connected in water. The favorable influence of negative electricity of low tension on germination is attributed to the decomposition of saline substances, and conse quent evolution of alkaline matter, which assist germination by combining with and neutraliz ing the acetic acid always evolved during ger mination and the growth of bulbs and buds. While the experiments quoted are interesting, it is the fact that so far, electricity has never been profitably applied artificially in the cultivation of plants. It is hardly a supposable case that it ever will be. It is, however, not uninteresting for the farmer to know the effects of direct elec trical influence. Smut, rust, and other fungus growths have been more than suspected to be the effect of electrical action. If some easy and cheap means could be perfected, by which apply electrical action to large areas, either nega tive or positive, cheaply and at will, it might be• found of advantage to the agriculturist.