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THURSDAY, MAY 17, 1906.

THE MECHANISM OF THE UNIVERSE. History of the Planetary Systems from Thales to Kepler. By Dr. J. L. E. Dreyer. Pp. xii+432. (Cambridge University Press, 1906.) Price 10s. 6d.



Y the publication of this masterly account of the development of cosmogonic ideas and the history of planetary systems from the early dawn of Greek philosophy to the final establishment of the Copernican system, Dr. Dreyer has rendered a great service to those who take an interest in the fascinating history of astronomical science. Throughout the work we have reason to admire his lucid exposition, based on profound historical studies, of the manifold views formed by the thinking minds of antiquity and of the middle ages on the mechanism of the universe, his

definite conclusions on many controversial points, and,

above all, his endeavour to trace out, as much as pussible, the influences of the philosophic and religious tendencies of the time on the cosmological conceptions under view.

The opening chapters describe the development of astronomical ideas among the Greeks. After a brief review of the cosmogony of the early atomistic school we are introduced to the more distinct teachings of the Pythagoreans. To their conception of the revobution of the earth round the central fire, notwithstanding its crudeness, distinct merit must be attributed, if judged by the favourable influence which the teaching of Philolaus exerted on the propagation of the Copernican system among those "who could only admire philosophers of classical antiquity." Complicated and erroneous as the Pythagorean idea was, it nevertheless paved the way for the true conception of the earth's rotation, but not, as was often believed, for the heliocentric system. The chapter on the primitive geocentric cosmology of Plato may, at first sight, appear somewhat too prominent. Considering, however, the various controversies to which Plato's astronomical system has given rise, a clear statement of his natural philosophy on the basis of an exhaustive analysis of the Dialogues is of importance, even apart from the author's apology that "there is a charm in the poetical conception of the * soul of the world' which makes the study of the Timaeus peculiarly attractive."

With Eudoxus and Kalippus astronomy has started on its career as a science. Eudoxus is the first to go beyond mere speculative reasoning; he distinctly bases his system of the homocentric spheres on the demand of satisfying the observed motions. The possibilities of this mathematically elegant system, recently pointed out by Ideler and Schiaparelli, were, however, not much appreciated by the ancients, although Aristotle had accepted it in the improved version of Kalippus.

Dr. Dreyer's criticism of Aristotelian metaphysics

is severe.

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His careful and critical examination of the opinions of previous philosophers makes us regret all the more that his search for the causes of phenomena was often a mere search among words. This tendency, which to us is his great defect, appealed strongly to the medieval mind and helped to retard the development of science in the days of Copernicus and Galileo."

The attempts of finding the physically true system of the world terminated with Herakleides, who taught the rotation of the earth, and Aristarchus, who proposed, as a way of "saving the phenomena," that the earth performed an annual motion round the sun. But the rapid rise of practical astronomy in the Alexandrian school had so enormously increased the knowledge of the complexities of the planetary motions, which none of the proposed systems could explain, that henceforth the idea of grasping the physical truth was altogether abandoned, and attention became concentrated upon a purely geometrical interpretation of the celestial phenomena.

The subsequent exposition of the theory of the epicycles and their utilisation in the Ptolemaic system work. We cannot enter here upon his valuable acnaturally forms an important part of Dr. Dreyer's count of the work of Apollonius, Hipparchus, Eratosfascinating picture of the advances in astronomical thenes, and Ptolemy; nor can we dwell upon his knowledge during the Alexandrian era, including, as they do, the discovery of the precession by Hipparchus, general conclusions as to the dimensions of the the mensuration of the earth by Eratosthenes, and universe. The chapter closes with a graphic account destruction of the Alexandrian library, when "the of the rapid decline of Hellenic culture after the Greek science had played its part so well and so curtain went down for ever on the great stage where long."

The return to archaic cosmology in Europe under telian metaphysics in scholasticism, mark an epoch patristic influence and the supreme sway of Aristoof scientific decadence in gloomy contrast to the flourishing period of Hellenic culture. But the same epoch is distinguished by the intense cultivation of Greek astronomy among the Arabs, whose labours, devoted to the further development of the Ptolemaic system, are expounded in chapter xi. Although no direct advance in cosmic ideas accrued from their work, they influenced the subsequent advancement of European astronomy in a most important manner by their invention of the trigonometric calculus.

The description of the revival of astronomy in Europe brings us face to face with some interesting philosophers of the pre-Copernican period. The vague and often mystic speculation of Cusa is contrasted with the practical merits of Peurbach and Regiomontanus, who successfully endeavoured to utilise the Ptolemaic system for the purposes of astronomical calculation, while we also find an interesting account of the hopelessly complicated attempts made by Fracastoro and Amici to revive the theory of solid spheres, and thereby to prove the physical truth of the Alexandrian system.


The three closing chapters dealing with Copernicus, Tycho, and Kepler are naturally those which command our special interest. They contain far more than mere statements of the works of these great heroes of astronomical science. They define clearly the specific rôle played by each of these actors in the revolution of scientific thought. In following the author through his analysis of "De revolutionibus," we realise not only the great mental power but also the heroism of the “quiet student at the shore of the Baltic," and we feel the importance of the moment when his work is ushered into the world with Osiander's apologetic introduction. We must agree with the author's endeavour to show how little Copernicus could have been influenced by Philolaus and the vague ideas of Aristarchus, whose anticipations detract nothing from the originality of his own thoughts. On the other hand, the exposition of the defects of the system is so lucid that it requires no intimate technical knowledge of astronomy to recognise the necessity of modification, which so immediately urged Tycho to the invention of his ingenious compromise between the geocentric and heliocentric conception. How far Tycho's all-important work as an observer has paved the way for the final recognition of the true system by Kepler is admirably shown in the last chapter, where the author opens before us the successive paths along which, through a labyrinth of errors and failures, the never tiring genius of Kepler was finally led to the "golden portal of truth." The long and weary road he had to go before he finally broke away from the time-sacred idea of circular motion and the Ptolemaic punctum aequans, and proved conclusively the elliptic character of the Martian orbit, is brought before us by an exhaustive analysis of his works, the study of which is so highly instructive, not only from the scientific, but also from the psychological point of view. The reproach, often levelled against the author of the "Mysterium Cosmographicum," of having filled his books with all sorts of mystic fancies, is, in Dr. Dreyer's opinion, founded on a misconception of Kepler's object in making his investigations. "There is the most intimate connection between his speculations and his great achievements; without the former we should never have had the latter."

We cannot attempt to enter upon the author's review of the opinions of science and church on the Copernican system during the time between Kepler and Newton, with which, on the whole, the student of history is familiar, though it is particularly interesting to hear on this matter the verdict of an historian who has derived his knowledge so directly and completely from an exhaustive study of the original prints and manuscripts.

It is difficult to emphasise sufficiently the specific merits of a work of this kind in a brief review. Doubtless not the least of its many meritorious features is the lucidity and conciseness of exposition. In its endeavour to grasp the essence of the cosmogonic ideas the mind is nowhere impeded by an unnecessary accumulation of cumbersome detail. At the same time the non-mathematical reader is sup

plied with sufficient technical information to secure his acquaintance with the principal geometry of the cosmic systems under discussion. This latter advantage is important in the case of a work which is clearly not written for a limited circulation among the small section of astronomical experts, but may justly claim to appeal to all who are interested in the history of the general development of scientific culture.

PROF. EHLERS'S "FestschrifT." Zeitschrift für wissenschaftliche Zoologie. Vols. lxxxii. and lxxxiii. Festschrift zur Feier seines siebzigsten Geburtstages am 11 Nov. 1905, Herrn Geheimen Regierungsrat Prof. Ernst Ehlers. Band i., pp. iv+692; Band ii., pp. 741; and plates. (Leipzig: Engelmann, 1905.) 2 vols., price 51. whose honour THE distinguished zoologist in

these volumes are issued is widely known as an indefatigable worker and one of the most genial Ehlers has for many years edited the journal which of men. Together with the late von Kölliker, Prof. now celebrates his seventieth birthday. As a testimony of the inspiring character of his teaching and of the regard in which he is held this "Festschrift " gives abundant witness. With no less clearness it indicates the diverse activities of modern zoologists and the particular problems upon which they are engaged.

With such a varied content, the volumes are difficult to review. The systematic work, admirable as it is, and coordinating or expanding as it does our knowledge of annelids, starfish, and flat-worms, can only be mentioned; nor can we do more than indicate the purport of a few of the many anatomical and physiological papers.

The place of honour is appropriately given to von Kölliker's paper on the histogenesis of the verte. brate nervous system, the last contribution of the master of histology, whose amazing vitality at eighty-seven years enabled him to conduct researchi and to discuss difficulties of fact and interpretation with unabated zeal. The month in which this latest defence of the neuron-theory was published brought the tidings that von Kölliker had ceased from work.

A long and exquisitely illustrated memoir by Vejdowsky gives a minute account of the structure and mode of origin of the annelidan vascular system. The nature of this system in the lower animals has been of late the goal of much research. Under the influence of the trophocoel theory, as stated by Lang on the basis of Bergh's work upon annelids, the vascular system has come to be regarded generally as a mesodermic structure, its cavities as a schizocoel, and not, as had often been suggested, a blastocœlic structure. The results of Vejdowsky's work have led him to a very different conclusion. First he proves, what had often been denied, that annelids possess a vascular endothelium. He finds that this "vasothelium" arises in the following way. Blood-vessels are intimately associated with the gut. Their cavities are at first simply a space between the outer ends of the gut-cells and their basal membrane. Into this space cells are budded off from the endo

derm. Some of these become differentiated into epithelio-muscle elements that constitute the vasothelium, and others into blood-cells. Thus the study of annelids leads Vejdowsky to conclude that their hæmocol is a hypoblastic structure sui generis, not comparable to that of arthropods or of molluscs, but rather to the cardiac vasothelium in vertebrates. Such a result emphasises that relation of vascular system to the alimentary tract which topography has insisted upon.

In his article on the morphology of the cestode body, Prof. Spengel stoutly supports the monozoic theory. He regards the Bothriocephalidæ as the most primitive tapeworms, and considers that in the highly modified Tæniidæ we have simply a coincidence of somatic and gonidial segmentation areas. Incidentally he suggests the comparison of the scolex with the hinder end of segmented worm, and emphasises the singular nature of the cestodes by pointing out their entire lack of true regenerative power.

is to be hoped that these important results may be rendered more available to the student of evolution than they now are by a new mode of presentation, graphic, tabular, or other than textual description.

Lastly, the memoir of the Baroness von Linden on the influence of heat, cold, and gases upon the coloration of Vanessid butterflies constitutes a further instalment of the author's prolonged investigation. The general conclusion drawn from these experiments is that whatever lowers the rate of pupal metabolism increases amount of black imaginal pigment and diminishes the extent of red colour in the butterfly. F. W. GAMBLE.


The Birds of Tunisia. Being a history of the birds
found in the Regency of Tunis. By J. I. S.
Whitaker. 2 vols. Royal 8vo. Pp. xxxii+294
and xviii+410.
Plates and maps. (London: R. H.
Porter, 1905.) Price £3 3s. net.

The remaining anatomical papers deal with the THE modifications of clasping organs in arboreal

mammals, with the head of collembolous and culicid insects, the nervous system of leeches, and certain abnormal gasteropods.

Of the embryological memoirs, the accurate and laborious research of Wierzejski on the cell-lineage of Physa will be welcomed as a topographical paper of the first rank. Prof. McIntosh contributes a well illustrated account of the life-history of the shanny, and then follow memoirs on the early development of the blind-worm, on the breeding habits of Rhinoderma and of the salamanders.

The physiological papers are of more general interest. Prof. Häcker continues his illuminating work on the skeleton of the Radiolaria by treating the Tripylaria from the same ecological standpoint which he adopted in his paper of last year. Häcker is the most active of a band of workers who are putting new life and new significance into the merely geometric descriptions of earlier students of these skeletal products. Dr. Rhumbler gives a further instalment of his work on the mechanics of streaming movement in Amabæ, and shows some interesting stream figures produced by dropping chloroform water upon shellac. He fully recognises the inward and autogenous control that dominates those displays in organisms that we cannot parallel in not-living matter, but he holds that in Amoeba the phenomena of movement and feeding are capable of mechanical explanation in terms of the aggregation theory which he has formulated elsewhere.

HE two handsome and beautifully illustrated volumes containing the history of the birds of the Regency of Tunis form a fitting crown to the years of work in the field, the museum, and the library which their author has devoted to the ornithology of this until recently little known country. They form too a valuable contribution to the avifauna of the western Mediterranean region; for although the present work purports to be merely a history of the birds noticed in Tunisia, and of their lives as observed in that country, the author has thought it advisable, when possible, to allude to the occurrence of the various species also in Algeria and Morocco, as likewise, in some cases, in Tripoli, and in the Mediterranean basin generally.

The articles on various warblers (especially the interesting remarks on their life-history), and other birds which are met with most commonly in that region, will be most welcome, even to those whose interests are restricted to the birds which figure on the British list. Tunisia, a long and somewhat narrow country, stretching from the Mediterranean back in the vagueness of the great desert, presents a great variety of natural features and climate; and the contrast between the well-watered, wooded and mountainous region north of the Atlas Mountains and the rainless, sandy and rocky desert country is very great. To these circumstances, and to the fact, pointed out by the author, that few countries are geographically so favourably situated as the Regency for the observation of the migration of birds, the wealth of the Tunisian avifauna is due. No less than 365 species and subspecies of birds are included in this work; and only about thirty-five of these have to be relegated to the roll of occasional and accidental visitors. Two beautiful photogravures give an excellent and most truthful idea of the character of the scenery and the traveller's mode of life in the south of the country; while other plates introduce the reader to some of those wonderful Roman ruins, so marvellously preserved in that dry, clear air, which so startle the inex

Dr. Jordan contributes an essay on the origin of species in Lepidoptera. His main thesis is to the effect that geographical subspecies, and no other variations, are the material out of which new species have been evolved. Much of the paper is summarised from his earlier work, and represents a line of research to which several naturalists are applying themselves. The work of Petersen on the Fritillaries in particular pursues the method employed by Dr. Jordan but in a more comprehensive manner, and itperienced wanderer in the central parts of Tunisia.


Each species is fully described, and a careful account of its distribution in Tunis, with some observations on its range in the neighbouring Mediterranean countries, is followed by an interesting and graphic account of its nesting habits, song, and life-history generally.

The four natural divisions into which the Regency may be divided appear to have each certain species peculiar to it, or more abundant in it than in the other regions. Besides this, in the case of some resident species, such as the crested larks, for instance, different forms of the same species are to be found in the different regions, the variation of these forms being in some cases considerable, and not always limited to the coloration of the plumage alone, but occasionally extending to the structural parts of the birds. The crested larks, says the author, afford a striking example of the extent to which local variation may be carried by natural causes, and no country probably affords a better opportunity of observing and studying this subject than Tunisia. The author is naturally in favour of recognising subspecies, and the use of trinomials for them; and his remarks hereon and upon what constitutes a species and a subspecies may be read with great advantage.

Many noteworthy and peculiar birds may be studied in Tunisia, but probably the families of larks and chats are better represented than any other; of the former twenty-one and of the latter eleven species and subspecies are treated, and the fifteen beautifully executed coloured plates which adorn these sumptuous volumes are largely devoted to illustrating these two families. Tunis is indeed especially rich in larks; and years of study, a long series of specimens collected by himself, and an examination of the various types in museums and the literature of the subject, added moreover to his having had the advantage of observing the birds in life, have enabled the author to clear up many puzzling points respecting the specific and subspecific value of the numerous forms of larks. have here a very clear and lucid exposition of the larks of the western Mediterranean basin; and especially of the crested larks (the most puzzling of them all), of which the author considers that there are two distinct groups, viz., one including the common crested lark of Europe, the other the smallbilled crested lark of Southern Spain, each with its allies.



The necessity for protective colouring is doubtedly great in a country like Southern Tunisia, where the scanty vegetation affords but little shelter to its feathered denizens. Hence it is that the plumage of most of the species resident in the desert and semidesert region harmonises with the sandy coloration of the soil. This is especially remarkable in the larks. But the author points out that although at first sight it may appear curious that the chats, except in a few instances, are spicuously coloured, it will, however, be found that the conspicuously attired chats frequent, as a rule, rocky and broken ground full of dark clefts and fissures, where the rocks are sometimes black and in other cases of a glittering white, and in such situations a strongly marked plumage is really far less

more or less con


spicuous than a uniform light coloured one would be. The ravens also remain as black as ever, but they. too, frequent cliffs and rocks for the most part, and their case seems analogous to that of the rock-haunting chats. Two good maps enable the reader unacquainted with the country to follow the author's O. V. APLIN. remarks on its topography.

British Fresh-water Rhizopoda. Vol. i. By James
Cash, assisted by John Hopkinson. Pp. x+148+
xvi plates. (Ray Society, 1905.) Price 12s. 6d.



'HE important discoveries that have recently been made on the morphology of Protozoa have revived the interest in British fresh-water amoebæ and their allies, and a monograph on the subject has been regarded for some time as a special need of the zoologist.

As a

Mr. James Cash has been known for some years as an ardent microscopist with a special knowledge of the forms and habits of the species of fresh-water rhizopoda in the north of England, and he has given us in this volume the benefit of his experience in this line of work, illustrated by many beautiful original drawings of the living organisms. work of reference for the names of species, and in so far as it suggests to the young amateur naturalist exercises for his amusement and instruction, it will be useful; but as references to important details of structure and reproduction are in general meagre, often misleading, and in many instances omitted altogether, it will not supply the need that is felt. The description of the cell (p. 3) as "physiologically, a minute vesicle, or closed sac, the enveloping mem brane or cell-wall enclosing the protoplasmic substance in which the functional phenomena reside," appears to us singularly unfortunate in an introduction to the study of the Protozoa.

The description of the nucleus is very short, but long enough to contain considerable extracts from the work of Calkins, whose views the author adopts, but there is no reference to the chromidial network which the recent papers of Hertwig, Schaudinn, and others have shown plays such an important part in reproductive phenomena of many rhizopoda. It is disappointing to find no reference, either in the introduction or in the systematic part, to the evidence of a developmental cycle in the life-history of Amoeba, based on the researches of Scheel and Calkins.

In the very brief account of the reproduction of Arcella, again, although Hertwig's important paper published in Kupffer's Festschrift is included in the list of references, the statements made are incomplete and misleading. Many other criticisms similar to these could be made, but the critic is disarmed by the confession in the preface that the author has not "investigated very closely the physiological problems associated with the life-history of these organisms." With this confession before them, it seems difficult to account for the action of the council of the Ray Society in undertaking the publication of this mono

graph without previously enlisting the services of a trained morphologist, with special knowledge of the group, to correct and revise the introduction and the morphological details in the description of the genera.

A monograph written by Mr. Cash, with the cooperation of a good morphologist, might have been one of really first-rate importance. As it now appears, however, useful as it may be in some respects and valuable in others, it is not complete, and does not constitute a serious advance of knowledge.


Physikalisch-chemisches Centralblatt. Band i. and i. (in parts). (Berlin: Borntraeger, 1903–1905.) We have received the first two volumes of the above serial, the first number of which was issued on December 15, 1903, twenty-four parts and authors' and subject indexes appearing annually. Besides the German title, the cover bears the titles "PhysicoChemical Review" and "Revue physico-chimique,' and the abstracts of French and English papers are given in the respective languages, all others being in


The periodical is edited by Dr. Max Rudolphi, of Darmstadt, with the collaboration of chemists and physicists in various parts of the world, London being represented by Sir W. Ramsay. Most, if not all, of the papers abstracted would doubtless be found to be noticed in other publications, and although the multiplication of such serials is not to be commended, this one may appeal to physical chemists who prefer to find abstracts on their own subjects separated from those of general physics and of inorganic and organic chemistry. In order that the serial should be useful to workers, it is necessary that the abstracts should

be given as soon as possible after the publication of the original papers from which they are taken. It would not be just to criticise a serial in its infancy, but some of the abstracts mght have appeared earlier; possibly their publication has been unavoidably delayed, and as time progresses the cause of this reproach will be removed. The periodical is well printed and contains many tabulated results.

The Philosophy of Martineau in Relation to the
Idealism of the Present Day. By Prof. Henry
Jones. Pp. 37:
(London: Macmillan and Co.,

Ltd., 1905.) Price is. net. THIS thoughtful and eloquent address, originally delivered at the celebration of the Martineau centenary, contains much more about absolute idealism than

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about the philosophic system of the great Unitarian preacher. Prof. Jones, after pointing out the close agreement between Martineau and the Idealists in several respects, finds his text in the division made at the beginning of "Types of Ethical Theory between systems that start with nature or God, and those that start with the spirit of man. Absolute idealism, of course, ranks under the former head, and the idiopsychological ethics of Martineau under the latter. So in the remainder of the paper the doctrines of absolute idealism are re-stated in a form such as might rob Martineau's chief objections of their force the objections, in particular, that ethical interests are not conserved, and that a refusal to sever man from nature and God means that man is merged into them and lost within them. Whether the reader will think this re-statement absolutely convincing or not will probably depend on his previous sympathies. Prof. Jones takes occasion, in passing, to notice the

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similarity of Dr. James Ward's "activity" and Martineau's "free will" as philosophic explanations, and takes occasion, too, as in many other recent utterances, to have one or two clever flings at the Pragmatists.

The Romance of the South Seas. By Clement L. Wragge. Pp. xv+312, with 84 illustrations. (London: Chatto and Windus, 1906.) Price 7s. 6d.


IN connection with Mr. Wragge's work as Government Meteorologist of Queensland, he paid a visit to New Caledonia, with the view of establishing a weather-observing station there. In this book he gives an account of his visit to the island, and also to Řarotonga and Tahiti. We wish there were more information in the book about the meteorological results of his journey. The volume contains instead simply a chatty account of the islands; and the most interesting matter is the author's visit to the convict prisons in New Caledonia. At Tahiti he paid a pilgrimage to Point Venus, where Cook on June 3, 1769, observed the transit of Venus. The author is enthusiastic over the scenery in both islands, and the only thing that justifies the mention of "romance" in the title is the spell of their scenery. The author's style is very discursive, and the book is full of smoke-room gossip and snatches of sailors' songs. It is illustrated by some good photographs, and in an appendix is a list of some shells and corals which the author collected in the Society Islands.

The Wild Fauna and Flora of the Royal Botanic Gardens, Kew. Kew Bulletin of Miscellaneous Information, additional series v. Pp. vii+223. Edited by Sir William Thiselton-Dyer. (London: H.M. Stationery Office, 1906.) Price 2s.

THIS volume is the combined work of a number of well-known zoologists and botanists, each of whom has made a special section the subject of his own investigation; it ought, therefore, to be exhaustive and trustworthy, as indeed it appears to be. The chief interest attaching to a catalogue of this nature is in relation to the important evidence it will afford in the future as to how a country fauna and flora become gradually modified as their surroundings become altered with the incoming of suburban conditions. Many such changes have already taken place in the animal and vegetable products of Kew; and many more are likely to take place in the near future. One of the most remarkable instances of adaptation to new conditions in the London parks and gardens generally is afforded by the wood-pigeon, which in the country is one of the wildest and shiest of all birds. A conservative spirit-possibly in the case of the mammals a little too conservative-we are glad to see, obtains in the matter of nomenclature.

R. L.

Physical Chemistry, and its Applications in Medical and Biological Science. By Dr. Alex. Findlay. Pp. 68. (London: Longmans, Green and Co., 1905.) 25. net.

THIS little book makes its appearance at an opportune moment, for no one engaged in biological work can now neglect the teachings of physical chemistry, and the great influence which this branch is exercising on the development of the biological sciences. It is just the sort of work the physiologist, pathologist, bacteriologist, and scientific medical practitioner needbrief and at the same time dealing in a simple manner with fundamental facts. The author thus reviews diffusion, osmosis, cryoscopic methods, and the study

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