EXPLANATION OF PLATE CIV.

FIG. 1. From a drawing taken from the woodcut in Chapter xxvi. of Sir John Maundevile's "Voiage." This should be compared

with the woodcut† at p. 388, borrowed by Prof. Max Müller from Gerarde's "Herball."

,, 2. Taken from fig. 3 of a plate in the "Phil. Trans.,” accompanying Sir Robert Moray's "Relation concerning Barnacles.' This seems to supply a link between the mythical epoch, as represented by Gerarde's figure, and that of fact, as represented by the following diagram.

99

3. Diagram of the capitulum of a Lepas, showing the relations of the various factors of the shell, reduced and modified—e.g. by turning it upside down, for better comparison with fig. 2 -from Darwin's figure (fig. 1) at p. 3 of his Monograph on the Lepadida. (c) Carina.‡ (t) Tergum. (s ct) Scutum. (u) Upper Latus. (s cr) Subcarina. (c) Carinal Latus. (im) Infra-median Latus. (r) Rostral Latus. (sr) Subrostrum. (r) Rostrum.

,, 4. Drawn by the author from a specimen belonging to the University Museum, Oxford. The bottle containing it is thus labelled:-"Conchoderma Hunteri, on carapace of a crab from Amoy. The eye is situated in this species on the oral side of the adductor, the reverse of its position in Lepas." On the right side, three of the Cirripedes are in situ, while, on the left, only one out of two originally adherent remains, the position of its former neighbour being indicated by a scar-like pit in the carapace of the crab.

,, 5, 6. Modified from woodcuts in Darwin's "Monograph of the Cirri

66

pedia," illustrating the homologies between this group as represented by a Lepas (fig. 6), and the Crustacea, as represented by one of the Stomapoda (fig. 5). Those somites" of the Crustacean body, which are present in the Cirripede, are coloured dark, those being merely left in outline which have no representative in the latter group. (p) Peduncle. (c) Capitulum. (cr) Cirri. (e) Eye. (a) Antennæ. (cp) Carapace.

„,7,8,9. Reduced and modified from figures in Tafs. viii. ix. of Prof. Häckel's "Natürliche Schöpfungsgeschichte." Fig. 7 is the larval form (Nauplius) of a Lepas, such as may be conveniently represented by the preceding figure, while figs. 8, 9 respectively illustrate the Nauplius and adult stage of a

By kind permission of Messrs. Ellis and White, the publishers. † Kindly lent by Messrs. Longmans.

Made up of three factors in fossil species of Scalpellum.

Crustacean proper (Cyclops). The main object of these figures is to demonstrate the fact that, however dissimilar in their adult forms may be the representatives of the various divisions of the Crustacean stock ("Stammform "), they have a striking similarity, making allowance for differences in minor particulars, in their larval stage.

FIG. 10. "Complementary male" of Scalpellum Vulgare attached over fold in "occludent margin" of the scutum of the hermaphrodite. Reduced and modified from fig. 37, tab. x. of Carus' "Icones Zootomicæ," taken from fig. 9, pl. v. of Darwin's monograph. (0) Orifice of sack of male. (p) Spinous projections above the rudimentary valves. (c) A transparent border of chitine-supporting long spines-which forms a border to the "occludent margin" of the scutum of the hermaphrodite. (d) Depression for the adductor scutorum muscle of the hermaphrodite.

At the top of the figure are represented, as seen through the whole thickness of the animal, the prehensile larval antennæ. For comparison with the above, see the figure of the male of Scalpellum regium, given in one of Prof. Wyville Thomson's "Notes from the Challenger," in "Nature," August 28. 1873.

401

REVIEWS.

THE

AMERICAN RECORD OF SCIENCE.*

HE Americans are attempting in their own country what has been attempted with the most signal failure in this. They are trying to publish, with successful results, an annual work recording the progress made, not only at home, but throughout the entire world, in the whole field of scientific research. The only book of the kind which our own literature possesses is that production which is known as the " Year-Book of Facts," a volume which we need hardly add is absolutely worthless as a scientific record. The present American work is got up on a larger scale; and is, so far as selection of paragraphs is concerned, edited with a certain selective skill, which renders it much more valuable as a scientific volume. But in saying this we are giving it all the praise within our power. For most assuredly it is unrepresentative, as of course every such volume must be. It is, as a matter of course, interesting to the mere "dabbler" in science; and we doubt not there are sufficient of this class alone in America to render its publication successful; but as a purely scientific book it has no real value whatever. Let us take an example in order to prove the force of what we say. Chemistry alone is not one of the most widely diffused branches of knowledge, yet the monthly journal which is published by the "Chemical Society," and which consists almost exclusively of condensed paragraphs showing the work that is being done, would in two of its numbers fully equal in bulk the present volume. That is to say, the progress of chemical science alone, in a single year, would, if recorded, occupy six times the space that is covered by the present work. When, then, we take the numerous other branches of science into consideration-such, for instance, as Anatomy, Physiology, Botany, Zoology, Geology, Paleontology, Mineralogy, Physics, Mechanics theoretical and practical, Astronomy, Ethnology, Meteorology and Microscopy-we see how utterly impossible is such a book as the present one if it really be intended as a record of science for the scientific worker. If, on the other hand, it is addressed, as is our own brief summary, to the man of general scientific tastes, then we must regard it as a very excellent volume; and most probably it is in this light that the editor, Mr. Spencer F. Baird, views the work. Examined under this aspect

"Annual Record of Science and Industry," for 1872. Edited by Spencer F. Baird, with the Assistance of Eminent Men of Science. New York: Harper Brothers, 1873.

the book proves a most interesting one; the records are, in most instances, up to date-though in a few this is not so--and in general are well selected. Moreover, the work is well got up, and printed, considering its American origin, in very good clear type. We fancy the editor does not receive the "Monthly Microscopical Journal," as he records Dr. Hudson's discovery of Pedalion mira as being a novelty taken from another journal; whereas, as histological readers are aware, this very singular and interesting rotifer was described nearly a year earlier by Dr. Hudson in a communication to the "Monthly Microscopical Journal." We observe also that in the Report of the Royal Commission on Scientific Education, the critic confounds the secretary with the members. Withal, the book is interesting and instructive, and we wish it every success.

PROFE

TYNDALL'S AMERICAN LECTURES.*

ROFESSOR TYNDALL is certainly the Helmholtz of England, if not something better still. We have often had to give him what might appear, to those ignorant of the man, unseemly praise, but which we felt we were thoroughly honest in awarding. And often all our encomiums were modest indeed when contrasted with those ebullitions of kudos which our American brethren have very recently indulged in. Dr. Tyndall has seemed to electrify them, and we do not wonder at their tendering him the highest praise, for now in the work before us we can see the reason of it all. Here is a book which gives the words in which the English lecturer indulged, and we cannot wonder that the various audiences which he addressed were wellnigh, enraptured with their speaker. For assuredly it would be impossible to find within our language a work in which more eloquent words are employed to detail more striking facts, and withal are addressed to an audience essentially unscientific it its character, and which can yet appreciate, to a very intense degree, the wonders and the beauty of the principles set forth.

We know of no work in the whole range of natural philosophy which deals with its subject in such clear and incisive words as the present one; and furthermore we find in it the difficulties of optics explained in a fashion which for clearness and intelligbility stands unrivalled. We may point to one or two portions of the work, in which the style is singularly lucid. And in the first place we may take that portion in which its author seeks to explain, to a popular audience, the exact nature of diffraction. This is an exceedingly difficult matter to make people comprehend, but we think Dr. Tyndall has happily succeeded in making it understood. We cannot follow him in his explanation, for it would take us too far and would occupy too much space; and therefore we leave it for the reader himself. But what, for instance, could be simpler than the passage in which Dr. Tyndall explains the error of the mighty Newton. "Newton," he says,

* "Six Lectures on Light," delivered in America in 1872-1873. By John Tyndall, LL.D., F.R.S., Professor of Natural Philosophy in the Royal Institution. London: Longmans, 1873.

"who was familiar with the idea of an ether, and who introduced it in some of his speculations, objected, as already stated, that if light consisted of waves, shadows could not exist; for that the waves would bend round the edges of opaque bodies and agitate the ether behind them. He was right in affirming that this bending ought to occur, but wrong in supposing that it does not occur. The bending is real, though in all ordinary cases it is masked by the action of interference. This inflection of the light receives the name of diffraction."

On all other branches of the important subject on which he has lectured the matter and manner of delivering it is the same, and we might chose many quotations if space permitted. But we must conclude with one more excerpt. It is upon the subject so often of late years illustrated by Dr. Tyndall, in his Institution lectures-the identity of heat and light in their mode of passage. "Perhaps," says he, "no experiment more conclusively proves the substantial identity of light and radiant heat than the formation of invisible heat-images. Employing the mirror already used to raise the beam to its highest state of concentration, we obtain, as is well known, an inverted image of the carbon points formed by the light rays at the focus. Cutting off the light by the ray-filter, and placing at the focus a thin sheet of platinized platinum, the invisible rays declare their presence and distribution by stamping upon the platinum a white-hot image of the carbons." A series of illustrations show at a glance the mode in which this interesting experiment is conducted.

The author's remarks on Fraunhofer's lines are also full of interest and instruction, but we cannot go into the subject. His concluding lecture is an eloquent peroration, and must have mightily charmed his audience. To the savant it seems to us that not the least valuable part of the work will be the quotations from Lord Brougham's attack on Young, and Young's able and masterly-written defence of which we learn with sorrow, from his biographer's sketch, that only a single copy was sold. Altogether we have been fascinated by this work of Dr. Tyndall's, and we doubt not that its readers will be vast in numbers on this side of the Atlantic and the other.

HAVING

NICOL'S MINERALOGY.*

AVING passed through a first edition, this book has now a second time come before the public, and in our opinion it is much improved in its new guise. Doubtless there are not a few who will object to the system of classification adopted by the author, some fancying the crystallographical the only method, while others as strongly uphold the plan which is based on the chemical composition. But it seems to us that the author has adopted a wise course in his effort to steer between the two. And we fancy his mode of arranging minerals, while it is by no means complete, is

"Elements of Mineralogy," containing a General Introduction to the Science, with Descriptions of the Species. By James Nicol, F.R.S.E., F.G.S., Professor of Natural History in the University of Aberdeen. 2nd Edition. Edinburgh: Black, 1873.