tion of electrical action in the organic compared to that which appears in the inorganic world. The general conclusion we have arrived at is the following:-viz., That during those actions which are termed organic, such as secretion, absorption (lacteal), and nutrition, there is then manifested the same power as is observed during ordinary chemical actions—a manifestation of electrical action. If we wish to have a clear view as to the resemblance between these actions-between the organic and the ordinary chemical actions-we must refer to the changes which occur in the decomposing cell of an ordinary voltaic battery, or to those which occur in a simple voltaic circle. And here we cannot refer to a more beautiful experiment than the one recorded by that eminent philosopher Wollaston* for the sake of illustration. The difficulty which might exist in some minds of perceiving the resemblance may naturally arise from the circumstance, that in the ordinary voltaic circle we have metals, and it requires, consequently, some mental effort to perceive clearly the resemblance which can exist between those actions (secretion) which occur, for instance, in the mucous membrane, and those which occur in the simple voltaic circuit. Although in the ordinary simple voltaic circle one of the metals is usually acted upon chemically, we should bear in mind that they serve principally as conductors, and that they are not essential for the development of the power. Again, the resemblance which occurs between those actions which take place when two fluids (an acid and an alkaline) are separated by a membrane and those which occur during secretion, however similar in their nature, nevertheless, in some respects differ: take for instance the secretion in the kidney or liver; here we have the fluid (blood) on one side only, whilst the secreted product passes through; in the former case, with the acid and alkaline solutions, we have combination between the two fluids; in the latter case, during secretion, a separation-not a mere transudation, however, but a secreted product; nevertheless, during the formation of this secreted product and its separation from the blood, the same effects are produced, the same actions occur upon the needle of the galvanometer as would occur if we cause the separation

* Phil. Mag., vol. xxxiii., p. 488.

of an acid from an alkali when in combination with each other-in short, a decomposition; and this is what actually takes place either in the decomposing cell of a voltaic battery or in that beautiful experiment of Wollaston in the simple voltaic circle. And as we say that the power in the voltaic circle is brought about by chemical* means, so may we say that the same power is brought about in the animal body by organic means. But it may be asked, what do we understand by organic means? In what do they differ from chemical means? What is the real difference between organic action and chemical action? And to these questions we have no hesitation in saying that we believe them to be both polar in their character; and as we speak of chemical polarity so may we speak of organic polarity, and consider that organic force and chemical force are both POLAR,† and so far identical.

Since this paper was presented to the Royal Society we have had the opportunity and extreme pleasure of perusing the valuable researches of Professor Graham on Osmotic Force.‡ The chemical character which Professor Graham assigns to osmose is of extreme interest to the physiologist; and the analogy which exists between the changes which occur in the organic world during the absorption and secretion of fluids and during ordinary osmose, is too remarkable to be overlooked.

* The dispute in reference to the origin of the power in the voltaic circle, whether by contact or chemical change, will make no difference to our argument. As far as we can make out, the dispute, in most instances, arises more from the meaning of the terms employed and the extent of their meaning, than from any real difference of opinion.

We have spoken of organic polarity in connection with chemical polarity, inasmuch as we are able to prove, by experiment, the resemblance between these two powers. Other polar phenomena may also occur in the organic world which might differ as much from chemical polar phenomena as magnetic polar phenomena do from the latter. In other words, the organic form of force might differ from the chemical form as much as the magnetic form does from that of the latter, or from that of heat, light, and electricity; nevertheless, they are mutually connected and correlated. That the force manifested during organic actions is polar we may consider as established upon experimental evidence.

We might refer to several authorities who have suggested the idea, or even pointed out the polar character of some of the organic actions; to Todd and Phil. Trans. 1854.

In ordinary osmose the employment of two fluids is apt to prevent the resemblance between it and secretion or absorption to be at first sight clearly perceived; but when the existence of osmose is made to depend upon the changes which occur in the membrane or any other porous septum, the necessity of two fluids is removed, and we then obtain clearer views as to the analogy or even resemblance between the processes which occur in the organic and inorganic kingdoms, between osmose on the one hand, and secretion and absorption on the other.

On the Occurrence of Scalariform Tissue in the Devonian Strata of the South of Ireland. By ROBERT HARKNESS, F.R.SS. L. & E., F.G.S., Professor of Geology, Queen's College, Cork. (Plate I.)

The existence of vegetation in the form of ferns, during the period of deposition of the strata which now constitute the Devonian formation in the South of Ireland, was first recognised by Mr Jukes and the officers of the Irish Geological Survey. The announcement of this took place at the Belfast meeting of the British Association, and these fern remains were referred by the late Professor E. Forbes to a new form of the genus Cyclopteris, the C. hibernicus; a plant which was subsequently observed by the same distinguished palæontologist among strata of this age in Scotland.

Besides these distinct remains of the C. hibernicus, which consist of a rachis having leaflets attached thereto, and which are common in the sandstones of Kiltorkan and the neighbourhood of Cork ;* there are found in some of the higher beds of the Devonians of the South of Ireland great quantities of Bowman's Physiological Anatomy, vol. i. p. 237, et seq., and especially to Dr Carpenter's valuable paper on the Mutual Relations of the Vital and Physical Forces in the Phil. Trans. 1850, p. 727, for further arguments in support of the same idea. Dr Todd, however, appears to us to have been the first to give the most precise and definite idea in reference to nervous polarity that we are aware of (vide Art. on the Physiology of the Nervous System in the Cyc. of Anat. and Phy.); and also to a small work, entitled "The Anatomy of the Brain and Spinal Cord," by the same author.

* Jukes, in the Journal of the Geol. Soc. of Dublin, vol. vi., p. 266.

drifted vegetable matter usually in the state of fragments of stems, but sometimes having a more perfect form, and presenting a stem with several branches issuing therefrom. This is the case with some of the higher beds in the immediate neighbourhood of Cork, which consist of yellow sandstone, and this circumstance also occurs among the greenish purple sandstones which are seen in the district about Abbey Mahon, 11⁄2 miles E.S.E. from Timoleague, in the same county. These stems are, in some cases, marked externally by a whitish shining micaceous-looking substance, and immediately underneath this there is frequently exhibited the fibrous silky substance which is generally known under the name of mineral charcoal;* and, in one instance, an isolated small mass of this mineral charcoal was found imbedded in the purplish sandstone.

On submitting the fibrous substance obtained from underneath the micaceous-looking external surface of the stem to microscopic examination, it was found to manifest traces of structure which were distinctly scalariform; and a portion of the small imbedded mass exhibited this in great perfection, clearly proving that the vegetables of which it originally formed a part were ferns. (See Plate I.)

So far as I am aware, this is the earliest evidence we possess of scalariform structure; and, although the fern character of the leaflets which occur among the higher portion of the Devonian deposits of the South of Ireland is sufficiently developed to justify these leaflets being referred to this tribe of plants, still the evidence of the internal structure is a matter of some importance, since it shows the great abundance of these plants during the period when the upper Devonians were being formed.

There is also another matter of interest in connection with the occurrence of scalariform structure so low down among the paleozoic group. This is the recent discovery of the Stangeria paradoxa, an existing African Cycad with a mode of leafing more nearly allied to Ferns than Gymnosperms, and the rarity of finding in the paleozoic ferns any manifestation of the organs of fructification, a circumstance which occurs in connection with the Cyclopteris hibernicus.

*Edin. New Phil. Journal, vol. i. P. 71.

NEW SERIES.--VOL. IV. NO. I.—JULY 1856.

These two features when combined, would, to some extent, render doubtful the Filicine nature of many of the plants, which have been regarded as appertaining to this tribe of vegetables. The discovery, in connection with one form of these plants which has not exhibited organs of fructification, of decided fern-tissue renders the absence of these organs a matter of small importance, and we must regard this absence as resulting either from the easily detached state of the organs themselves, or from some circumstances in their constitution which render the preservation of the fructification difficult.

Mr Jukes, to whom I am indebted for the information concerning the position of the strata at Abbey Mahon, informs me that the plants are not confined to the upper Devonian. They also occur in the Coomhola grits of the Irish Geological Survey, which form the base of the Carboniferous formation, and in which are found Orthocerata, Modiola, Avicula Danmoniensis, Spirifer cuspidatus, and Encrinites; these fossils being confined to the carboniferous, while the upper Devonians are devoid of marine remains.

Although these ferns cannot be regarded as strictly Devonian forms, still their occurrence in strata of this age indicates that they owe their position in these beds to different causes from those which have mingled them with the marine ferns of the succeeding carboniferous; and many geologists have regarded their presence as indicating the existence of fresh-water or estuary conditions during the latter portion of the Devonians; a circumstance which is still further confirmed by their being, in some localities, associated with beds containing the remains of the Anodon Jukesii. Whether or not they have been carried into fresh-water lakes, in which flourished the shell just alluded to, is a matter which, until further evidence is obtained, will remain doubtful. We have, however, quite sufficient proof that a luxuriant vegetation clothed the surface of the Devonian land, and that this vegetation had principally a fern character.

The geological structure of a considerable portion of the South of Ireland shows, that during the deposition of the Devonian beds, there was, above the surface of the sea, a large tract of land on which probably grew the vegetation occurring