66

REVIEWS.

THE ELECTRICITY OF THE BODY.*

IT is unquestionable that the number of workers in pure physiology in this country is extremely small, for example, as compared with either Germany or Italy. Nevertheless, there are a certain number of earnest genuine men among us who have made, and are still making, valuable researches in physiological matters. And foremost in the ranks of these few must be placed the author of the present volume, who is almost alone in England the representative of Matteucci, Du Bois-Reymond, Pflüger, and Eckhard, and other workers in foreign countries. Not recently has he taken up the pursuit of animal electricity, but twenty years ago, and ever since has he devoted the leisure hours obtained from a heavy practice to the pursuit of the electricity of animals. And it is the more remarkable because he has, in the book before us now, given wholly up many of the views which were held as true in his former volumes. We say this because we think that it is infinitely to the author's credit that he has openly admitted his mistake and gone on another tack of scientific discovery. Of course men in the open pursuit of science will readily understand how an author may make mistakes. There is not a day nor an hour when our chemists and astronomers and zoologists are not making mistakes of the most serious character, mistakes which are calculated to leave each of their sciences on the stand-still for years; but we are sorry to say that they do not always confess their errors as candidly as the author of the present volume. We do not mean to say that they knowingly conceal their mistakes, or endeavour to give a semblance of truth to what they know to be false doctrine; but they fail to see their errors till they have spent whole years of their life in bitter and hostile controversy. Therefore we have nothing but praise to award Dr. Radcliffe for the honesty and openness of his avowal.

In the present volume he sets to work in real earnest at his subject, and he has given us the fruits of his later years' researches. These involve work done with Sir W. Thomson's "New Quadrant Electrometer," and the new "B.A. Unit of Resistance," which was devised by the late Dr. Matthiessen, F.R.S., when he was lecturer at St. Mary's Hospital. It is clear, therefore, that through the employment of these two instruments quite a new field

"Dynamics of Nerve and Muscle." By Charles Bland Radcliffe, M.D., F.R.C.P. London: Macmillan and Co., 1871.

was opened up; and it is this field which Dr. Radcliffe has laboured at so energetically and well. For example, he has found that a single inch of the frog's sciatic nerve exposed a current of electricity to a resistance equal to 40,000 B.A. (British Association) units, or as much as "eight times that of the whole Atlantic cable." But it is with the new and wonderfully exact instrument devised by Sir W. Thomson that his most remarkable researches were conducted, and we may quote a few lines to show this.

"Seeking for tensional phenomena of animal electricity in muscle and nerve by means of the new quadrant electrometer, I soon found that the sides and ends of the fibres were charged differently—the former positively, the latter negatively-and that these evidences of charge disappeared in a great measure during action. I soon found the evidences of the charge for which I had searched before almost in vain; but I found more than I expected. Expecting to find a single charge, I found a double charge; and what to think of this state of things I could not at all see at first. The facts would not chime in with preconceived conceptions, and the end was, that the conceptions had to be modified to suit the facts."

The idea previously held by the writer was quite the opposite of this, for it conceived that the muscular fibres were charged with one kind of electricity during rest, and that in this way the molecules were kept in a state of mutual repulsion. But this idea was impossible to reconcile with a belief that there was a double charge of electricity in each muscle, and this latter was unquestionably a fact. Here, then, a new series of views forced themselves on Dr. Radcliffe's attention, viz. that the natural electricity present in the muscle produced the state of muscular relaxation and elongation in a different way from what he formerly supposed; that the tissues presented a great resistance to electricity; that the sheaths acted as dielectrics; that this being the case, a charge of one kind of electricity on the outsides induced a charge of the opposite kind on the insides of the muscle, and the electric antagonism of the sides and ends was accounted for by the induced inside charge being conducted to the ends by the contents; and, finally, that the fibres might be kept in a state of relaxation by compression of the sheaths, "arising from the mutual attraction of the two opposite charges, disposed, as in a charged Leyden jar, upon the two surfaces of the sheaths." All these views are borne out by ample experiments, which are fully described by the author, but which we have not space for here. Dr. Radcliffe has found that all the tensional phenomena of the muscular fibre and all the current phenomena also, can be easily imitated upon a wooden model of the fibre left bare at the two ends and at the sides, sheathed with a coating formed of two layers of tinfoil, separated by a thin layer of gutta-percha, if only a charge was supplied to the outer tinfoil layer. He also produced experimentally the elongation of the fibre. This he did on a narrow band of india-rubber, covered on its two surfaces with a thin metallic coating, so as to allow of its being charged in the same manner as a Leyden jar. This appears to be a satisfactory model of a muscle, for it elongates under the influence of a charge of electric fluid, and, on the other hand, it contracts when the charge is discharged from it. This rude example seems abundant in favour of the view which the author works out so elaborately in the pages of the present work.

As regards the galvanometer, Dr. Radcliffe thinks it of little use in these inquiries, compared with the electrometer. The galvanometer does not tell us, the other instrument does, that the parts between the poles are charged half positively, half negatively. Yet this is intelligence which, the author assures us, cannot be dispensed with; for, as he proves further on, "the workings of voltaic electricity upon muscle are found to be resolvable into those of the charge and discharge of these very charges, and not into those of the constant current."

Another result which the author has arrived at is that the state of the muscles is a state of electrotonos, which state further bears out the ideas already alluded to. All through the work will be found abundant accounts of experiments made by the author and an ample description of the results obtained by Matteucci and Du Bois-Reymond, and others who have been engaged in similar researches. In point of style, the book is an exception, for Dr. Radcliffe writes, as few of his medical compeers can, with an elegance and terseness which are most unusual. The physical characters of the volume display the publishers' good taste.

WE

THE SUBTERRANEAN WORLD.*

E think, of all the works which Dr. G. Hartwig has given us, the present one is unquestionably the best; not only in its style, which is clear and simple, but in the information it conveys, which is full, accurate, and modern. We do not see any fault to find with the book, and we are sure that our readers will study it with a great deal of satisfaction, and with an intense interest in the manifold facts which it relates. The book may really be divided into four parts. First, there is the purely geological and paleontological; then comes physical geography; next we have mines and mining; and, finally, an account of minerals and gems. All this is well done; and the illustrations, although not excessively numerous, are nevertheless good ones of their kind. We shall endeavour to quote something from the principal sections, and thus give the general reader a better idea of the exact nature of the book. After giving a brief account of the different fossil forms which we have yet discovered, the author makes the following remarks on the important question, Has the animal world diminished in size as it has gone on?

"The colossal size of many of the extinct plants and animals might seem to favour the belief that organic life has degenerated from its forme powers; but a survey of existing creation soon proves the vital principle to be as strong and as flourishing as ever. No fossil tree has yet been found to equal the towering height of the huge Sequoias and Wellingtonias of California; and though the horse-tails and club-mosses of the carboniferous ages may well be called colossal when compared with their diminutive representatives of the present day, yet their height by no means exceeded that of the tall bamboo of India. No fossil bivalve is as large as the Tridacna of the tropical seas; and though our nautilus is a mere pigmy when "The Subterranean World." By Dr. George Hartwig. London: Longmans and Co.

compared with many of the ammonites, our naked cuttle-fishes are probably as bulky as those of any of the former geological formations. The living crustaceans and fishes are not inferior to their predecessors in size; and though the giant saurians of the past were much larger than our crocodiles, yet they do not completely dwarf them by comparison. The extinct Dinornis far surpassed the ostrich in size, but the mammoth and the mastodon find their equal in our elephant; and though the sloths of the present day are mere pigmies when compared with the Megatherium, yet no extinct mammal attains the size of the Greenland whale."

This quotation is a sort of conclusion to the portion of the book devoted to the history of the fossil animals upon the globe. It is followed by a general account of the physical geography of the earth; and herein is contained a long account of the various peculiarities of the globe, of the artificial wells, of earthquakes, volcanoes, and the several underground caverns which are to be found in different parts of the world. The chapter on earthquakes is about the most interesting, for it not only contains an account of the most remarkable of those dreadful commotions, but it gives the leading details of the more general disturbances which have taken place within the past couple of centuries. With regard to these, we may quote the author's remarks on the subject of earthquake shocks.

"Earthquake shocks are either vertical or undulatory. A vertical shock, which is felt immediately above the seat or focus of the subterranean disturbance, causes a movement up and down. Like an exploding mine, it frequently jerks movable bodies high up into the air. Thus during the great earthquake of Riobamba, the bodies of many of the inhabitants were thrown upon the hill of La Culla, which rises to the height of several hundred feet at the other side of the Lican torrent; and during the earthquake of Chili, in 1837, a large mast planted thirty feet in the g.ound at Fort San Carlos, and propped with iron bars, was thrown upwards, so that a round hole remained behind."

Numerous other examples are given, and the author concludes, with Mr. Mallet, that the rotating hypothesis is not correct, but that earthquake movements are essentially backward and forward movements. We much regret that we have not space for further quotations from this interesting volume. We may, however, just mention that there are hundreds of places from which we could quote with interest, such as the chapters on subterranean water-courses, on cavern animals, on ice-caves, on subterranean catacombs, on mines, and on the several minerals and precious stones. However, we must now conclude our notice, and offer our best thanks to Dr. Hartwig for the very capital treat his pages have afforded us.

MR

A POPULAR HISTORY OF BRITISH INSECTS.*

[R. J. G. WOOD has written us so many and good manuals on different branches of British and general zoology, that we had almost imagined he had come, so to speak, "to the end of his tether," and that we

"Insects at Home; being a Popular Account of British Insects, their Structure, Habits, and Transformations." By the Rev. J. G. Wood, M.A., F.L.S. London: Longmans and Co., 1872.

should not have any more of his popular works to review in these pages. We are happy to say that we have been mistaken, for the work we have now under notice, if it is not one of his best works, is certainly by no means an illustration of the theory that as a writer advances in public favour, he, as a rule, diminishes in excellence. In point of fact, the "Insects at Home bears evidence of being carefully prepared by the author, and it is very well illustrated by its publishers. Of course it must be borne in mind that we are speaking of it as a merely popular work; for if we were to criticise under any other view, we should have to call many of the views expressed by the author into serious question. Taking it, then, as a popular book, we may express ourselves as very well pleased with the author's labours. To be sure, he has not dwelt much on the anatomy of the insects, but then he has omitted this specially, because he does not, we suppose, think that so many are interested in it; but on the habits of the several insects he has described, we know of no work, save the immortal "Kirby and Spence's Entomology," which contains so much information.

Of Mr. Wood's method of classification we cannot speak very favourably; but then most probably he would say in opposition to this, that he did not consider the subject at all, and merely gave that classification which he found most generally adopted; and with this argument we can find no fault whatever. There is, however, one suggestion which he makes in his preface to which we must call attention; it is as to colouring the plates. These, he suggests, may be readily coloured by the reader, and he gives the various means by which the process of coloration may be completed. We entirely object to this. If the author had sold with the work a number of plates which, if damaged, would not deface the book, we could not object; but such a suggestion to most readers of the volume looks like a "Yankee desire to improve the sale of the work by the destruction of copies--a desire which we are sure the reverend author never for a moment conceived of.

As regards the substance of the book, we can only say that it is full to overflowing with accounts of the beauty, intelligence, and peculiar habits of all species of insects which have their home in these islands, and that it concludes with some practical hints on the subject of mounting the specimens which the young entomologist has captured. Although the anatomy of the work is, as we have said, remarkably deficient, still here and there it finds a place, as, for instance, in the account of the great green grasshopper, in which the author says: "Among other points, one of the most interesting is the 'gizzard.' Before it is opened it looks very like a swelling of the digestive tube; but if it be carefully slit horizontally and spread flat, a number of narrow parallel bands will be seen. On placing one of these bands under the microscope, it will be seen to consist of a number of very small teeth, arranged with perfect regularity, and admirably calculated for triturating morsels of the leaves which have been cut off by the powerful jaws, and then swallowed. As for the jaws themselves, their power may be easily ascertained, for the insect is generally given to biting." We thoroughly coincide with Mr. Wood in his recommendation of Lowne's "Anatomy and Physiology of the Blow-fly;" and we can go further than he does, and say of it that it is the most important monograph, with some noted exceptions, that is to be found in any language on the anatomy of a