lively and varied: now it sails swiftly along, tumbling over and over occasionally in a rollicking fashion; now it rotates perseveringly on its axis; now it moves restlessly over the surface of the vessel in which it is confined, as if searching for something. The decline of its activity is the sign that the first stage of its existence is drawing to a close.

The cilia are borne on a delicate membranous envelope, within which the solid contents of the body are seen as an opaque white mass. At one pole of the body is placed a somewhat horseshoe-shaped opening, at the extremity of which is a tuft of long bristles that lash the water vehemently and incessantly. This opening is without doubt a mouth; I have seen rejectamenta passing from it. At the opposite pole is a circular depression, forming a kind of bowl, the margin of which is surrounded by very delicate cilia. This, as Nitsche conjectures, is very probably a sort of sucker by means of which the embryo attaches itself. I have little doubt that this is the true interpretation of it, as I have noticed that this portion of the body is always applied to the surface on which it rests. some species minute red pigment spots are present at certain points on the surface of the body, in which a refractile corpuscle is embedded. Are these to be regarded as the equivalent of eyes?

In

When its term of free life is ended—that is, when it has attained the proper stage of development-the embryo fixes itself, loses its cilia and the whole of its characteristic structure, and now appears as a membranous chamber inclosing a mass of granular substance; and from this mass the polypide gradually buds. The foundation of the colony is thus laid.

A word in conclusion respecting the curious appendages with which so many of the calcareous Polyzoa are furnished, and which bear the names of vibracula and avicularia.* The former are long and slender bristles placed close to the cells, which move incessantly, with much energy and a certain rhythmical sweep, over the surface of the polyzoary. They are, as it were, jointed at the base and supplied with a special apparatus of muscles, and their function plainly is to prevent the accumulation of noxious matter in the neighbourhood of the polypides. The avicularia are developed in extraordinary profusion and variety throughout a large portion of the class. They are best described as miniature birds'-heads, and are furnished with a movable lower jaw which they keep in constant play, now throwing it back with ludicrous vehemence, and after a while closing it with a malicious snap. Many of them are fixed,

Both these organs may be studied to great advantage in one of the commonest of our British species, the Scrupocellaria scruposa.

and their action is confined to an incessant exercise of the lower jaw; but in some cases they are mounted on a kind of joint, on which they swing backwards and forwards in a halfrhythmical way, opening and closing their mouths with prodigious vigour.

I am not aware that any recent observations have been made tending to throw light on the relation which these curious organs bear to the economy of the Polyzoan. The capture by the avicularia of small worms, which are much given to wriggling in and out amongst the branches of the colony, has often been observed; and I have been surprised to find an unhappy captive of this kind still in durance and still living after the lapse of two or three days. The birds'-heads may also be seen frequently with a quantity of dirt between their beaks, as if their office too might belong to the scavenging department. I have referred to them, however, for the purpose of noticing the familiar fact, that they continue their movements after the disappearance of the polypides, and may often be seen in full play when there is no sign of life in the rest of the colony. The explanation is that the common nervous system, on which they are dependent, no doubt retains its energy for some time after the death of the polypides; and, further, that in a large number of such cases, though the cells are tenantless for the time, the life of the colony is not really impaired, but a company of the "Groddkapseln" is on the point of supplying it with a new population.

65

REVIEWS.

THIS

THE UNIVERSE.*

THIS is the epoch of luxurious scientific publications, and this year is almost its acme. Never, within our recollection, have we seen so many editions en luxe of scientific treatises as the past twelve months have produced, and to conceive of anything which can in future years surpass in magnificence those of 1869 would be simply impossible. It is in no ecstatic spirit that we employ these words. Exaggerated as the praise may seem, it is, in fact, but a "plain unvarnished" statement of the extravagance in mechanical execution to which English publishers have recently gone. In one sense the circumstance is to be rejoiced in, as it shows that enterprise receives encouragement, but in another sense it is to be regretted, for it tells us the too apparent truth, that the popular scientific works, with elaborately gilt covers and illustrations which are artistically excessive, are the necessary bait to induce the British public even to nibble at the hook which philosophy throws out to capture superstition.

Of all the exquisitely "got up" books that have come under our notice, this work of M. Pouchet's, which Messrs. Blackie have issued, is, in its English garb, the most splendid. Whether we look to the type, the paper, the binding, or the multitude and quality of the engravings, we are still bound to confess that in these respects it cannot be surpassed. This is more than can be said even for most of the books of this class, for when we come to the "matter" they contain, we generally observe a quantity of garbled facts ill assorted, badly conveyed, often at variance with each other, and frequently misunderstood by the reckless compiler, who has written the book "to order." This expression of opinion would apply to a very considerable number of the popular scientific treatises which have of late been imported into this country from France. But let us clearly state that it would not at all apply to the present work, which is really a sterling book, notwithstanding that it attempts an account of all the natural objects which surround us. We fear that a great many persons-even of those who think themselves educated-will be disposed, from the external features of this book, to rank it with M. Figuier's successful réchauffées. If this should occur, it will be a great mistake, and one much to be regretted. We have

"The Universe; or, the Infinitely Great and the Infinitely Little." By F. A. Pouchet, M.D., Corresponding Member of the Institute of France. Translated from the French. London: Blackie and Son, 1870.

a very good opinion of M. Figuier and his compilations; but to compare him with Pouchet, or to class the books of the two in the same category, would be a monstrous injustice to the latter. M. Pouchet has his faults; he is given occasionally to confounding inferences with facts, and to dogmatising a little too strongly on points in heterogeny; but, whatever his sins, he is not to be regarded as a scientific quilldriver, but as an earnest and industrious investigator in some of the most difficult paths of science. We trust, then, that readers will understand that, in writing a popular treatise, M. Pouchet is coming down from his usual pedestal of research to do a good work-to lend a hand conscientiously to the furtherance of a knowledge of science among the people.

M. Pouchet's book, then, is just such an one as might be expected of its author. In accuracy it leaves nothing to be desired. Its scope is immense, and therefore the method of dealing with the several subjects is of a general kind, details being, as far as possible, avoided; but it is not on this account sketchy. If the colours are laid on roughly with the knife, there has been a careful study of the tout ensemble, the effect is Turneresque, and the whole picture is one-not pre-Raphaelitish, showing us a myriad of small things, but-which gives us a fine broad landscape in which the universe itself is depicted.

And what does this book tell us of? asks the enquiring reader. In answer, let us say that it treats upon all, or nearly all, natural phenomena, and some unnatural ones. The leading facts in zoology, from the polycystin to the elephant; in botany, from the bacterium to the palm; and in geology and palæontology, from the simplest elementary fact in ordinary denudation to the consolidation of a glacier or the elevation of a mountain range, from the foraminifera of the chalk to the huge Dinornis or Megatherium, all find a place in M. Pouchet's history. And on all he tells us if not something new, at least something put in a new fashion, and in forcible, vivid language, and in a way which gives us something besides the fact-gives us an idea of its relation to other facts, and suggests something additional in the way of generalisation. The style is fresh and vigorous, like that of a preacher whose heart is in his sermon and whose congregation doesn't slumber. In short, the author carries his reader along with him. All sections of the work are good, but we fancy the entomological portion is a little too extended, not absolutely so, but in relation to the other departments. The author's notes are numerous and carefully prepared, and are well supplemented by those of the editor, who, we may remark, has drawn largely on our pages for material.

The portion of the work to which our interest attaches most largely is the last, in which M. Pouchet gives a popular sketch of the arguments for and against heterogeny or spontaneous generation. The critics have overlooked this a fact not surprising when we mention that the chapter opens on page 712, and that some reviewers believe, with Sidney Smith, that impartiality cannot be exhibited if the critic extends his reading beyond the title page. Here, however, is to be found the best outline of this important controversy which has yet been given. We exclude M. Pennetier's book because it is in French. In this chapter the English general reader is first initiated into the important discoveries of Pouchet, Musset, and others, and

we believe that the result of his study of it will be his nearly entire conviction of the inadequateness of the theory of Panspermy. But whatever he may think of this part of the book, he cannot fail to be pleased with the work as a whole, and he will, we doubt not, appreciate the remarkably good English of the translator, and the very great enterprise of the eminent publishers who have introduced the book into Great Britain.

THE SUN.*

OF all the discoveries which have been made during the present century

in the department of astronomical physics, very few are more remarkable than those which have been made concerning the sun. The solar spots and the solar prominences have, during the last ten years or so, occupied the attention of European and American astronomers, and the hypotheses which have been started in explanation of these phenomena have been as numerous as conflicting. It is not at all surprising, therefore, that a work should be published upon the solar phenomena as a whole; indeed, the only thing to be wondered at is that such a work should have made its appearance in France and not in England, where the labours of De la Rue, Huggins, Loewy, Stewart, Lockyer, and Stoney have done so much to advance our real knowledge of the constitution of the sun. M. Guillemin, the author of the work which Dr. Phipson-a former contributor to these pages-has introduced to the English public, is an old friend of English popular astronomers. His work on "The Heavens," translated some time ago by Mr. Lockyer, is familiar to most educated persons, and, as it deserves to be, is a favourite. The work on the sun will, we trust, be equally well received, for it is an excellent summary of what has been discovered of the nature and motions of the sun from the earliest times to the remarkable spectroscopic researches which, in 1868, revealed to us the true character of the solar prominences. M. Guillemin has had a vast series of facts to collect and describe, and he has discharged the task taken up by him conscientiously and successfully, producing not merely a dry record of the history of astronomical research, but a most seductive and forcible sketch of the progress of solar science. The book is well illustrated and well written, and he must be a dull man indeed who cannot find in its pages much, not only to interest and instruct him, in the ordinary sense of the word, but also to lift his mind above the mere commonplaces of life to the contemplation of that grandest of all great secrets, the cause and end of celestial phenomena. In his labour of translator Dr. Phipson has performed his duty creditably. The book reads like a work written in English, and not simply rendered from another tongue. We have not space to discuss any of the problems treated upon by the author; but we would especially direct attention to his analysis of the different theories-of Kirchhoff, Faye, and others-as to the constitution of the photosphere. The judicial manner in which he contrasts all without leaning

"The Sun." By Amédée Guillemin. From the French by T. L. Phipson, Ph.D. London: Bentley, 1870.