following wounds of nerve-trunks. The appearance of the skin in this condition has been likened by Mr. Paget to that of chilblains. The integument becomes red and polished, in spots or patches. The hair is wanting. Sometimes the sensibility remains as usual; sometimes it is increased; sometimes diminished. The case cited as exceptional is curious enough. A man received a bullet wound, apparently implicating the axillary artery and musculo-spiral and median nerves. Very early in the case his first and second finger and thumb slowly enlarged without any premonitory signs, and with slight darting pains.' This continued after the wound had closed. Two months after the wound the skin of the affected part peeled off en masse. Seven months after the injury, when the case was last seen, sensation was wanting in the first, second, and half of the ring finger, and in the half of the thumb, though neuralgic pains were referred to these parts. The palm and first two fingers were enlarged. The skin was thickened, and of a dark purple colour. It is not surprising that the American surgeons should be struck by the resemblance between this and the disease called Elephantiasis Arabum. While in India, we have several times seen two or three fingers enlarged to twice the size of the others, and the skin pink and glossy, contrasting with the black skin of the rest of the hand.

"Other lesions of nutrition or secretion following wounds of nerves are also pointed out. Sometimes there were copious acid sweats; sometimes there was dryness or desquamation of the skin, vesicular eruptions, or incurving of the nails, or subacute inflammation of the joints, favouring the conclusion that the lesion of the nervous trunks acts upon the nutrition of the parts, independently of the loss of sensation or motor power."

The nutritional lesion at the peripheral distribution of the nerve, however, may, if it persist sufficiently long, become in its turn the causative condition of what was in the first instance but a result in common with itself of the lesion of the nerve-trunk. For Dr. Mitchell "claims the merit of having pointed out what was practically unknown before his own researches, namely, that loss of motor power, in a vast majority of cases, is finally due less to neural defects than to those obstinate consequences in the range of nutrition which result from the loss of nerve-power, and which may continue long after the motor power has been partially or completely restored."

Many similar cases may be found recorded by Mr. Jonathan Hutchinson in a very valuable paper, consisting of "Observations on the Results which follow the Section of Nerve-trunks, as observed in Surgical Practice," which was published in the 'London Hospital Reports' for 1866. Mr. Hutchinson is inclined to explain the phenomena of lessened temperature and those of lessened power of maintaining temperature which accompany these lesions, by the lessened

vis a fronte of the tissues surrounding the capillaries and acting then upon the circulation. The present writer is only half inclined to believe that this is a vera causa in animal hydraulics or "hæmaulics;" and that at all events we are not absolutely necessitated to accept it as such, though the absence of any other plausible hypothesis may be seen from the following record of an observation made and published by him before he was acquainted with either of the two memoirs just referred to. This record will be found in 'Medicine in Modern Times,' at p. 69, and to the following effect :

"The following short history seems to me to be a good instance of the action, or rather of the want of action, of the peripheral nervesystem upon the arterioles. A man, who came some years ago under my own care had had a bullet pass through his arm just above the elbow, so as to sever the musculo-spiral nerve. The scars of exit and entrance were in the lower third of the arm. Under ordinary circumstances the soft parts of the lower arm maintained their natural consistence; but their power of resisting changes of temperature was greatly impaired, as well of course as the sensibility of the parts supplied by the injured nerve. I recollect seeing the swollen state of the inner side of the hand one cold, raw morning, when the man was on sentry duty, and had his hand chilled down by the musket he had to carry. Now, I apprehend that this turgescence is to be explained by saying that the local or peripheral nerve-system of the affected parts was competent under ordinary circumstances to regulate the calibre of the arteries; but that its activity was liable to be depressed, as under the circumstances related, into actual abeyance in the absence of any possibility of any assistance being supplied to it from the cerebro-spinal nerveaxis. Thus, under the depressing effect of cold, which seems to work here much as it does in checking the regeneration of artificially amputated parts in snails and in salamanders,* the peripherallyplaced ganglionic system was put into abeyance, and turgescence of the vessels it ordinarily supplied with 'tone' ensued.”

It may be said that we do actually know and can see that a nerve when severed from its central connections undergoes fatty degeneration; that it is reasonable to suppose that its mal-nutrition may entail a consentaneous mal-nutrition in the parts which it supplies; and that this secondary mal-nutrition may account for the reduction thus witnessed of the tissues of warm-blooded animals to the level of those of the cold-blooded classes. But to this we reply that atrophy of the nerve-trunk is one thing, and a thing very demonstrable; whilst atrophy of the terminal nucleate plexus, in which so many nerves have of late been shown to terminate, is another thing, and as yet an undemonstrated one. Indeed the physiological existence *Müller's Physiology,' by Baly, 2nd edition, i., p. 444; Bonnet, 'ŒŒuvres,' tom. v., i., pp. 328, 329.

*

of these peripheral nervous apparatus has only just established itself as a fact in science, and so far as the writer is aware, nothing has as yet been attempted as to their pathological history. And weighing hypothesis against hypothesis, the writer still thinks his own, which would explain the facts in question as referable to an impairment of power, to be, at least for the earlier stages of the history, as probable as the counter-hypothesis, which suggests a consentaneous though early alteration of nutrition, as an explanation of the phenomena.

It may be well to add that the changes in question, or at least some of them, have been observed in non-traumatic cases of nervous disease, such as shingles affecting the arm.†

The cases which we shall now, in the fourth place, proceed to relate appear to us to show distinctly that nerve-force can act on tissues, and that directly, without, that is to say, any intervention of the blood-vascular system. The first of these is a typically good instance recorded by a typically good observer. In the twentieth volume of the Medico-Chirurgical Transactions' (1837) we find the late Sir B. C. Brodie writing as follows:-"A man was admitted into St. George's Hospital in whom there was a forcible separation of the fifth and sixth cervical vertebræ, attended with an effusion of blood within the theca vertebralis, and laceration of the lower part of the cervical portion of the spinal cord. Respiration was performed by the diaphragm only-of course in a very imperfect manner. The patient died at the end of twenty-two hours; for some time previously to his death he breathed at long intervals, the pulse being weak and the countenance livid. At length there were not more than five or six respirations in a minute. Nevertheless, when the ball of a thermometer was placed between the scrotum and the thigh, the quicksilver rose to 111° of Fahrenheit's scale. Immediately after death the temperature was examined in the same manner and found to be still the same."

Now temperature often rises in the presence of great lividity, in the absence, that is, of any but a very imperfect degree of arterialization or oxidation, though not, of course, in the absence of chemical change. Dr. Gray, of this place, informs me, as I write, that in a case of pneumonia, recently under his care, the temperature rose as high as 106° F. But in the case just quoted from Sir B. C. Brodie's memoir no such over-active cell-formation as that which characterizes pneumonia, and indicates its presence by monopolizing the currency of chlorides, can be reasonably supposed to have been present; and we appear to be shut up to the accepting as an explanation the showering down from the irritated and isolated segments of the spinal

* See Stricker's 'Handbuch der Lehre von den Geweben,' ii., p. 189, 1869.

Dr. Beale, 'Royal Society's Proceedings,' 1865, p. 249.

+ See Paget, Medical Times and Gazette,' 1864, March 26, cit. Handfield Jones, St. George's Hospital Reports,' vol. iii., 1868, p. 99.

cord of such an amount of stimulus as was competent to throw the tissues of the lower parts of the body into active chemical change. That this explanation is a vera causa the following facts will show. Dr. Semper, in his magnificent work on the Philippine Archipelago,* has given us an account of certain Echinodermata, of the class Holothurioidea, the source of the article of commerce known as "trepang," from which we learn that several of these curious animals have the power of dissolving their integument into a kind of amorphous slime, upon irritation even of so gentle a kind as simple removal from the sea water. In the case of one species, Stichopus naso, it has been found necessary to kill them by heating the water without removing them from it, as otherwise their dense integument runs into dissolution, and the animal is spoilt for the Chinese market, in which, when well preserved, it commands a specially high price. If, now, fragments of the integument of one of these creatures be placed under the microscope, and whilst there, be irritated with the point of a needle, the process of self-dissolution is observed to be expedited in direct correspondence with the amount of stimulus applied. In this diffluent slimy mass beautiful reticular and nucleate nerve-plexuses are to be seen, surviving, which is not always the lot of destructives, the destruction they have brought about. Nothing can speak more clearly to the "catalytic" power of nervous organs, unless it be the rationale given by Mr. Paget, as reported in the British Medical Journal for January 22, 1870, of the formation of sloughs and bed-sores. There Mr. Paget is reported to have observed that " simple loss of nerve-power is followed only by wasting of the paralyzed parts; but if in addition to loss there is disturbance of nerve-force, we then find disturbances of nutrition quickly following the injury, such as extensive bed-sores and sloughing of integument on the feet." To this we should add that if the nerve-system does not play the part of King Stork, other irritants may; and that animal structures deprived of the eminently animal assistance which a connection with a central nervous system secures to them succumb to shocks to which, when thus reduced almost to the level of vegetable tissues, they ought not in fairness to have been exposed. The discordant results of observations as to the consequences of paralysis of many, and especially of the trifacial nerves, can be harmonized if these two considerations are kept before the mind.

For the literature of this subject and much else that is valuable relating to it, see Handfield Jones, St. George's Hospital Reports,' iii., 1868, p. 89; Funke, Lehrbuch der Physiologie,' Bd. ii., 62 to 775; 1866: Herman, 'Grundriss der Physiologie,' pp. 79, 293, 298; 1867: Dr. Anstie, in The Practitioner,' March, 1870, p. 166. *Reisen im Archipel der Philippinen,' iii., 72; iv., 158, 171; v., 200. 1868.

V. RECENT OBSERVATIONS ON UNDERGROUND TEMPERATURE, OR THE CAUSES OF VARIATION IN DIFFERENT LOCALITIES. BY EDWARD HULL, M.A., F.R.S., Director of the Geological Survey of Ireland.

WITHIN the last year several series of experiments on the rate of increase of underground temperature of more than ordinary interest have been carried out, on which I propose to offer a few observations. On a former occasion I ventured to give a summary of the experiments which had at that time been carried out on this interesting branch of inquiry, and to point out a course which, in my opinion, would if adopted enable us to ascertain the rate of increase at depths hitherto unexplored.* It is satisfactory to find that the plan proposed has met with the approval of the Committee appointed by the British Association for the Advancement of Science, for the purpose of “investigating the rate of increase of underground temperature downwards in various localities." The report for the past year, drawn up by Professor Everett at the request of his colleagues, has now been issued, and contains an account of experiments undertaken by Sir William Thomson, F.R.S., and his assistant, Mr. McFarlane, in the vicinity of Glasgow, and by Mr. G. J. Symons at Kentish Town in the metropolis, at the deep boring of the New River Company. These observations were taken in water which filled the bore-holes, each layer or stratum of water being assumed to correspond in temperature with that of the surrounding stratum of rock; and the instruments used were those invented by Sir W. Thomson and Professor Phillips respectively for avoiding a source of error (though one not of much importance) arising from the pressure of the water at considerable depths on the bulb of the thermometer.

Of the two experiments made near Glasgow: one, taken at Blythswood reached a depth of 525 feet, with an ultimate temperature of 59-52°;† and the other, taken at South Balgray, reached a depth of 347 feet, with a temperature of 53 69°. At a depth of about 60 feet the constant temperature was reached, and the result obtained at the Blythswood bore was 1° for every 50.5 feet, and at the South Balgray bore 1° for every 41 feet, a rate of increase much in excess of the former; and, I may add, of the mean results of other experiments.‡

* Quart. Journal of Science,' vol. v. 1868.

+ All measurements of temperature in this paper are given in degrees of Fahrenheit.

The rapid increase in this case appears to have arisen from the large proportion of shale at the depth between 390 and 450 feet. Mr. W. Hopkins has shown that the increase of temperature is in the inverse ratio of the thermal conductivity. Phil. Trans.,' vol. cxlvii.