These reports I have from those who professed to have been eye and ear witneses of the thrilling scenes. Since the time just mentioned no remarkable phenomena have been noticed in the crater. It has been for the most part in a quiescent state, with more or less steam and smoke, and occasionally opening a small red eyelid, or letting loose a few fire flies upon the wings of the night.

During December of 1850 the smoke and steam are said to have much increased; and the occasional throe of an earthquake indicates that all subterranean action has not ceased. Kilauea is evidently assuming more of the manners and habits of the fiery sisterhood. Her exhibitions are becoming periodical, arbitrary, capricious. With the exception that her throne is not a mountain summit, she more and more resembles Etna, Vesuvius and the Andean and Asiatic furnaces.

The sulphur beds remain much as formerly, except, perhaps, that the bank within the crater has less heat and activity, and the one above, or near the hut has a little increase of heat. Most of the sulphur is now obtained at the beds near the hut.

The eruption of 1840 is still hot and steaming at many points along its course, and hundreds of steam holes are still smoking in Puna and parts of Kau.

There is now one cone feebly active at a little distance from the dome in the crater. Those on the dome are now inactive.

The eruption in Mokuaweoweo, or the great crater on the summit of Mauna Loa, was first noticed in May, 1849, some little time after the extraordinary activity of Kilauea. This eruption never overflowed the crater in which it occurred, but spent all its force within the bowels of that deep chaldron. For two or three weeks it shot up a tall, beautiful and brilliant column of light perpendicularly and to a great height; this column, like that which led Moses and the hosts of Israel, being "a pillar of cloud by day and a pillar of fire by night." At the end of two or three weeks it faded away and disappeared.

The eruption on Mauna Loa immediately succeeded the action in Kilauea. I cannot say they were coincident; though they may have been, as the mountain is, as you are aware, often obscured in clouds. Whether or not there were any connection between the two eruptions we cannot determine.

Note by J. D. DANA-If there was actually a connection in the instance above alluded to, the trifling effects observed may well excite our surprise: for how could so slight agitations be all the result, when the lava stands in Mauna Loa to a height of 10,000 feet above the great open pit of Kilauea on its slopes-10,000 feet higher in one leg of the syphon than in the other, the crater too at the summit being in eruption at the time? See this Journal, x, 244, 1850, and Proc. Amer. Assoc., Cambridge, 1849, p. 95.

ART. XIII. On the causes of the disengagement of Electricity in Plants, and upon Vegeto-terrestrial Currents; by M. BECQUEREL.*

SINCE the discoveries of Galvani and Volta, the researches on the development of electricity have taken a philosophical direction. It has been the object to discover not only the causes of its disengagement, but also the relations existing between electricity, molecular attraction and chemical affinity. The study of electrophysiological phenomena has also been pursued; and although to a less extent than other departments of this subject, the labors of Nobili, Marianini, Matteucci, du Bois-Reymond and others, show that general physics and physiology may alike profit by researches upon the presence of electricity in the operations of organic life and in the constitution of organized bodies.

The causes of the development of electricity in organized bodies, living or but a short time deprived of life, are physical, chemical and perhaps organic; and in the last case, they pertain to certain vital functions not yet clearly defined.

My object in this memoir is to exhibit the proper mode of investigating the physical and chemical laws operating in the production of electro-physiological phenomena, and also to give the results at which I have arrived in my researches on plants, whose simplicity of structure renders experiment more easy than with animals.

Some preliminary explanations are necessary to render the subject intelligible.

Organized bodies of the animal kingdom consist of osseous, tendinous, membranous, fleshy, &c. parts filled or moistened with liquids which render them more or less perfect conductors of electricity; and those of the vegetable kingdom, of woody fibre, vessels, &c., in which liquids are present with the same result. As the solids alone have no conducting power, the liquids act the principal part in the production of the electric effects observed, although vital action may intervene in some cases. These liquids, when two are in contact, necessarily produce through the resultant reactions sensible electric effects; observable not only with the condenser, by putting one of these liquids in relation with the earth and the other with one of the plates, but also with the multiplier by closing the circuit with two plates of platinum plunged in these liquids.

There may also be chemical reactions and currents without using the plates of platinum, when the solids and liquids are arranged as will be soon explained.

* Ann. de Chim. et de Phys., xxxi, 40, 1851.

In aiming to ascertain the chemical origin of the currents produced in the interior of an organized body, it should be remembered that if two different liquids, separated by a permeable membrane are put in communication by means of two plates of platinum in connection with a multiplier, the magnetic needle deviates in a direction which indicates that the liquid acting as the acid sets free positive electricity, and that acting as alkali, negative electricity. The intervention of metallic plates is here indispensable to the production of electric currents; but it is unnecessary when certain solid substances, non-conducting and permeable, and liquid conductors, are arranged as follows, as already explained to the Academy.*

If solutions of potash and nitric acid separated by a thin layer of clay are put in communication by means of two plates of platinum, the acid liberates positive electricity as I have just said. If we substitute for the plate a tube having the form of a U, one decimeter in length, filled with moistened clay free from lime, and so prepared that the part which is plunged into the acid should be less and less acid, and that in the alkali less and less alkaline, in order that there may be but a simple chemical reaction, we have then an apparatus by the aid of which, on breaking the tube so as to have two conductors, decompositions may be produced.

Similar arrangements to this are found beyond doubt within organized bodies consisting of solid parts more or less permeable, and liquids which mingle only with difficulty under the operation of life, on account of the tissues.

When public attention was first called to the admirable discoveries of Volta, Dr. Baccomio of Milant endeavored to construct piles of organic substances of vegetable origin, as Matteucci has for some years done with portions of animal muscle; but no true effects of the action of a pile were obtained. And how did Dr. Baccomio operate? He made a pile out of disks of the root of the beet, five to six centimeters in diameter and disks of walnut of like size, with which he caused a frog to contract, using as an excitor the leaves of Cochlearia. As there was nothing to prove that a similar effect would not have resulted from a single pair, there is no evidence for believing that the whole acted as a pile, especially if we consider the following facts.

M. Donné has obtained currents from animals and vegetables by putting in communication, by means of metallic plates or wires connected with a multiplier, liquids of different composi tion belonging to one and the same body and capable of acting chemically on the surrounding liquids. Having placed a plate of platinum in the mouth which is commonly alkaline, and

omptes Rendus, xxiv, 505.

+ Ann. de Chim. [2], lxii, 212.

the other upon the skin which secretes an acid, the needle deviated fifteen to twenty or even thirty degrees, the mucus of the mouth on account of its alkaline nature giving the negative current. M. Donné obtained similar effects by experimenting on the stomach and liver, one secreting an acid and the other an alkali. Analogous effects take place with fruits; on inserting a needle of platinum into the stem end of the fruit and another into the opposite, there is an electric current; in apples and pears the current is from the flower-end to the stem-end, and in peaches, apricots and prunes, the reverse. If the needles are inserted at opposite points, 90° from the ends, (that is in the equatorial plane,) there is no current. The effects obtained were evidently due to the different composition of the liquids. On cutting a prune in two equatorially, and then obtaining the juice from each, and making with it a circuit, the currents were obtained as before, and in the same direction. The cause in such cases is evidently chemical.

Similar results are obtained when experimenting in organized bodies with two metallic conductors, if they are put in contact with two different liquids separated by tissues or permeable membranes. A frog prepared as by Galvani may be used in place of metallic conductors; its contractions indicate the electric effects that are produced immediately when the circuit is formed.

May the effects here manifested take place without the intervention of metallic conductors or the frog? To this, I shall reply soon. I mention here, that whenever two liquids react chemically upon one another, if these liquids do not form part in a closed circuit, there is an immediate recomposition of the two electricities disengaged at the point of contact; but if one of the two liquids is put in communication with the earth, or loses by evaporation the electricity which it possesses, the electricity of the other liquid may be collected with the conductor. Such are the data for studying the questions under consideration in this memoir.

I. Electric effects produced by the Circulation of Sap.

In plants, there is an ascending sap and also a cortical sap, the latter differing in composition from the former, and having, according to some physiologists, a descending movement. They are separated by tissues and produce effects like those above mentioned. These effects are the more remarkable from their relation to the composition of the bark and wood. To interpret them, it is necessary briefly to recall what is known upon the nature and distribution of these two varieties of sap.

The stem of a ligneous dicotyledonous plant is formed of two distinct parts, the bark, and the wood properly so called, separated by a liquid substance considered by many physiologists a semifluid tissue, called cambium, which is the principal element of

vegetable organization. The bark consists independently of the parenchyma, of epidermis, laticiferous vessels and cortical fibres. The wood is formed of medullary rays, of woody fibre, and pith. The bark like the wood contains a cellular and a fibrous part but in inverse position. The parenchyma which is analogous to the pith occupies the exterior of the bark, whilst the pith is at the centre. This inverse position corresponds, as will be seen, to inverse electric effects.

As each stem or branch is composed of an uninterrupted series of concentric heterogeneous layers, their successive contacts ought to give rise to electric currents proceeding from the unlike char acter of the liquids moistening these layers. These effects are rendered sensible-1, by the aid of platinum needles introduced into two contiguous or more or less distant layers, reacting upon the neighboring layers; 2, by collecting with a condenser the electricity carried off from the plant by the vapor of water exhaled by the leaves and by the oxygen proceeding from the decomposition of carbonic acid under solar influence; 3, by using platinum needles in order to ascertain the simultaneous electric states of the plant and the earth.

The moisture of the earth enters the roots by their extremity through endosmosis and capillarity, passes into the cellules situated above, and reaches the stem where the ascending movement is continued: it dissolves some portions of substances in its course, increases in density, and constitutes then what is called sap. The ascent of the sap is due not only to endosmosis and capillarity, but also to the buds which by their growth draw up the stem and branches the material necessary for their development. The buds form leaves, which by affording evaporation, aid in the production of the ascending movement and are a means consequently of manifesting electric effects.

We know not with exactness the different organs passed through by the sap in its evolution. We can say only that in spring it fills the cellules, the fibres, vessels, &c., and occupies almost entirely the woody substance. The ascending sap, reaching the young branches, passes to the surface of the bark in the parenchyma as well as to the leaves; and when once spread in the green part, it is in direct connection with the atmospheric air, separated from it only by a thin membrane through which respiration is going on. The sap, which is thus intimately modified, becomes less aqueous through evaporation of a part of its water. Carbonic acid gas is decomposed, carbon is assimilated and oxygen exhaled. The color of the leaves and young bark shows that considerable changes are going on in the sap. Does this sap, newly elaborated, redescend through the bark, depositing along its passage material for the formation of tissues? Some physiologists still doubt on this point. But the experiments of