THURSDAY, FEBRUARY 23, 1893.

MAN AND EVOLUTION.

'ution and Man's Place in Nature. By Henry Calderod, LL.D., F.R.S. E., Professor of Moral Philosophy, niversity of Edinburgh. (London: Macmillan and )., 1893.)

HIS work appears to have been written for the purpose of setting forth the author's views as to the old nature and origin of man. He admits, fully and servedly, that both the bodily organism and the lower tal nature of man have alike been developed by a ess of evolution from a lower animal form; but he s with much force, and often with both eloquence and ctic skill, that the rational and moral nature of man not been thus developed.

he book, however, has many defects; and one cannot eel that the writer has undertaken a task somewhat nd his powers. Most prominent is its extreme diffuseand vagueness, the want of systematic treatment, the ient reiteration of the same ideas under different forms ords, and the misconceptions arising from want of liarity with many of the subjects discussed. We are annoyed by the frequent reference to problems to iscussed or solved, which are yet only hinted at or ed about later on. Thus, in the first chapter, we are that a "fuller study of human life" is now required, that the crowning effort of science in the study of ure must be "the solution of the problem of man's carance" on earth. Yet no attempt is made in the le volume, either to solve this problem or even to show t progress has been made towards solving it. At 54 we are told that " We are now ready for conration of Darwin's argument"-as to the relation of

mental nature of man and the lower animals. And on next page-"The direction to be followed now becomes e obvious"-after which we have pages of general arks on the intelligence of the dog and the ant. n, at p. 162-" The method to be followed is clear: must compare the higher animals with man"-and careful comparison of the two orders of life is the only rse open for scientific inquiry," and again,-" The culties belonging to such a mode of inquiry are many; no easier method is available." Then, at p. 167, we that Darwin "has at least suggested the essential ditions of our inquiry." After this we have another es of vague general remarks, till at p. 171 we find aner statement of the mode of inquiry, and we are told "we must have in full view all that is common to , as animal, with the higher mammals, making ount of close approximation in organic structure." we nowhere find any attempt to apply these prinles or methods so laboriously set forth, but are put off h such statements as-"In proof of exercise of intellince, examples are many and familiar, making it mecessary to enter upon detailed references." Then are interrupted by fifteen pages of remarks on instinct ong insects, although it has been repeatedly stated that relation of man to the higher animals was the probm to be discussed; and at p. 193, we are told that

"Now at length, after careful survey of lower levels, we advance towards the height, on which the grand problems of intelligence become visible. Study of comparative intelligence now becomes possible." Then follow again page after page of what can only be described as "general remarks" on horses, dogs, monkeys, and other animals. We are told, for example "When the higher animals are compared with the lower, it is clear that a power of intelligence must be attributed to the higher, which cannot be credited to the lower. Phenomena of domestication come to our aid here, confirming this generalisation." And a little further on, as a proof that dogs can interpret signs and act upon them, we have the following concrete illustration, among the very few in the book, and therefore we may presume it is considered a valuable one. "Go home' will send one dog back, but the Gaelic equivalent alone will be effective in the case of a dog reared in the Highlands of Scotland, where the Celtic tongue is in common use." And then, as if the intelligent reader might doubt this astounding fact, the author adds, "Observation affords ample testimony for this."

Although the author has evidently read very widely on the subject of evolution, his want of grasp of the subject is continually shown. Thus, when discussing the struggle for existence, he seems to think that this is usually considered to be limited to a struggle for food. He says:-" A general view of the relations of life and environment will guard against interpretation of facts exclusively by reference to struggle for existence consequent on the relations of numbers to food-supply." . . . "Life is too rich in variety to find adequate explanation of its history in the mere balancing of our numbers with food-supplies."

"In no life is progress to be explained exclusively by reference to amount of food-supply". . . "environment must be read much more largely than could be suggested by mere dependence on materials for nutriment" -the above passages all occurring in a single paragraph.

We have to thank the author, however, for the very clear manner in which he admits, and even enforces the application of evolution to man. He states this conclusion in several places. Thus, at page 261, we find the following:

"The novelty of the situation lies in this, that man's alliance with all animal life has been established with a clearness and fulness of representation never before possible in the history of the world. The long-hidden secrets of nature are disclosed, and, behold! man has his heritage among the beasts of the field. The discovery is indeed a large one; the demonstration has been worked out in minute detail till no place is left for doubt."

By far the best portion of the work is that which is its special feature the discussion of the rational as contrasted with the mere perceptive and intelligent nature of man and of the lower animals. A few quotations will explain the author's views, and show him at his best.

"The conditions of action are changed when rational self-direction comes into view. This change is so great as to amount to a complete contrast with all that has appeared in lower forms of life. Passion and appetite have not disappeared: they are present as before; but instead of determining conduct, a new exercise of powe has appeared to control them. Life has here a duality within it, which has not been seen at any lower stage.

Life's history becomes in this way a history of conflict, of which no trace has appeared at any earlier point in natural history. The struggle between individuals has not disappeared, but a struggle within the individual life occurs, which has never been visible in the history of any inferior order of life" (p. 55).

Another aspect of the rational nature is thus defined ::

"The difference which severs man from the animals lies beyond the craving, and the cunning, and the consuming of what has been captured. We trace it in his plans for the day, in his preparation of his weapons, in his survey of the heavens, in his taking of reckonings for direction. He deals with the relations of means to ends; he utilises past experience in his reflections over what has happened; he reaches general conclusions" (p. 270). Perhaps the finest passage in the book is at p. 287, tracing the moral element in the thought of all kinds of men and all diversities of race, as shown by the sense of wrong and injustice. We can only give here the concluding lines :

"To this appeals the criminal in the heart of our surging crowds, placed under arrest, if he should be condemned on insufficient evidence. To this appeals every buyer in the market, defrauded by the thrusting of adulterated goods into his hands. And to this does every gentle one make appeal, defrauded in ways still worse, by false expressions of love, from whose falseness recoils a blighted life, bearing through long and weary years witness to the cruel wrong that has been done. Where, along the devious paths in which man is found, is justice not honoured, at least by outcry against harsh wrongs? "

There is much in this volume that will attract readers more disposed towards the esthetical and moral than towards the scientific aspects of evolution. Agreeing, as the present writer does, with most of the conclusions of the author, he can but regret that they have not been set forth in a manner more likely to attract scientific

THIS

HIS work consists of two volumes, the first of which comprises a course of lectures delivered by the author in 1887-1888, whilst the second contains a further course delivered in 1891-1892.

The first volume commences with a discussion of the constitution of the luminiferous ether, in which the latter is regarded as a system of discret molecules in stable equilibrium under the action of molecular forces, and the author finally deduces equations of motion of the same form as those which are furnished by the ordinary theory of isotropic elastic media. He then adopts the hypothesis, originally due to Lord Kelvin, that the velocity of propagation of the longitudinal wave is practically The principle of Huygens is next dealt with, and this is followed by a chapter on diffraction. A complete discussion of all the difficulties attending the resolution of waves would carry us too far, but the author does not appear to be acquainted with the masterly

zero.

investigation of Sir G. Stokes, or the formula by him, which gives the effect of an element of a wave at a distant point, and which enables the factory reasoning on which the principle of He depends to be dispensed with. The diffraction of diverging from a focus is next discussed, and the of light diffracted by a circular aperture or disc is tained in the particular case in which the Do observation is the projection of the centre of the aper or disc upon a screen; but no mention is made of Lommel's able investigation in the general case c'. excentric point. A few stock problems relating to diffraction of parallel rays are also discussed, but nett is said about the resolving power of optical instrum or the theory of gratings, including Prof. Rowlands genious invention of concave gratings.

Chapter V. commences with the theories which he been proposed to explain the photogyric propertie: quartz and certain organic substances, and concludes an account of some of the theories of ordinary dispersor This is followed by a long chapter which begins Fresnel's theory of double refraction, and then proces to discuss the theories of Cauchy, Neumann, Sarra Bousinesq.

In all these theories the ether is regarded as a æolotropic elastic medium, and in considering the author is to be congratulated on having shown no sim pathy with the small minority who regard the wn down of equations as a foolish process; but althe during recent years much time has been spent in elas rating such theories, it may be questioned whether the majority of them have contributed any very substanta addition to scientific knowledge. The theory of the pagation of waves in an aolotropic elastic medium «3 rigorously investigated by Green as long ago as 1874. and although a theory of this kind is useful in enab the mind to form a mental representation of the mechan ism which is required to produce double refraction, £ # well known that Green's theory, and all others of a of this phenomenon. The principal defects of suct similar character, fail to furnish a satisfactory explanation

theories are, that although most of them lead to Fresse's wave surface, or to one which is a very close approxima tion thereto, they require us to suppose that the vibrations of polarized light are parallel instead of perpendicuz ? the plane of polarization; and they also fail to give resats which explain crystalline reflection and refraction, acles certain additional assumptions of a very questionable character are made. Probably it will not be thought a exaggeration to say, that the only theory of elastic mea which satisfactorily explains double refraction is the vot which is due to the joint labours of Lord Rayleigh, Lars Kelvin, and Mr. Glazebrook.

At the commencement of Chapter VII., which des with reflection, the following statement is made (see p. 320):

"La réflexion vitreuse a donné lieu à trois theer également confirmé par l'expérience, ce sont celle de Fresnel, celle de Neumann et MacCullagh et celle de Cauchy."

The theories of Neumann and MacCullagh depend upon the hypothesis that the density of the ether is the same in all media, and that it is the rigidity which

aries; and it is somewhat surprising that M. Poincaré oes not appear to be aware of the investigations of orenz and Lord Rayleigh, who completely exploded this ypothesis twenty years ago by showing that it leads to wo polarizing angles. The weak point in the investigaions of most French mathematicians on the subject of eflection and refraction arises from the fact that, in conequence of their not having made a careful study of Green's papers and the subsequent developments by Lord Rayleigh and Lord Kelvin, they are unable to deal satisFactorily with the longitudinal or pressural wave. The difficulties arising from the existence of these waves may be got rid of either by assuming, as Green did, that the ratio of the velocity of propagation of the longitudinal wave to that of the transverse wave is very large, or, by adopting Lord Kelvin's hypothesis, that the above ratio is very small; but it cannot be too emphatically stated that the existence of such waves must not be disregarded, and that any attempt to ignore them will inevitably end in failure.

This chapter concludes with a brief account of metallic reflection, in which the author has adopted the equations of motion given by Voigt. The chief difficulty in trying to explain metallic reflection, by the introduction of a viscous term into the equations of motion, is due to the fact that Eisenlohr has shown that for certain metals the pseudo-refractive index is a complex quantity whose real part is negative.

Turning now to Volume II., which consists of a further course of lectures delivered in 1891-1892, we find that it commences with the theory of isotropic elastic media in its ordinary form. Next follows a chapter on the electromagnetic theory, in which the author confines himself to the case of an isotropic medium, and has given no account of the investigations of Glazebrook on crystalline reflection and refraction, in which it is shown that the intensities of the reflected and refracted waves satisfy the same equations as those deduced many years previously by MacCullagh from an erroneous theory, but which nevertheless explain the facts in a fairly satisfactory manner. M. Poincaré assumes that the vector potential satisfies the solenoidal condition; but although the employment of the vector potential is valuable as a mathematical artifice, its use requires extreme care, inasmuch as it contains an undetermined quantity; and I believe it can be proved that in certain cases the solenoidal condition is not satisfied. In the electromagnetic theory of light this difficulty can always be evaded by eliminating the vector potential from the equations, which is the preferable course to pursue.

In Chapter V., after discussing ordinary reflection and refraction, the author attempts to construct an electromagnetic theory of metallic reflection and refraction by taking into account the conductivity. This theory leads to Cauchy's formulæ, but requires that the real part of the pseudo-refractive index should be positive, whereas Eisenlohr has shown that for certain metals these formulæ cannot be reconciled with experiment unless the real part is negative. In the case of steel this quantity is positive throughout the whole range of the visible spectrum; but as thin films of iron, when magnetized, exhibit anomalous dispersion, it is doubtful whether this hypothesis is satisfactory even in the case of steel or iron.

The next four chapters are devoted to the principle of Huygens and to diffraction; and in Chapter X. the author has discussed Von Helmholtz's theory of anomalous dispersion. The advantage of theories of the class to which that of Von Helmholtz belongs is, that they endeavour to account for dispersion and absorption by taking into account the mutual reaction between ether and matter, and show that when one or more of the free periods of the vibrations of the matter coincides with one or more of the free periods of the rays of the spectrum, absorption and anomalous dispersion will be produced. By the aid of this theory the absorption produced by sodium vapour may be accounted for, as well as the anomalous dispersion and selective reflection produced by fuchsine and other aniline dyes. The author has not, however, developed the consequences of this theory as far as might be done.

It is not unnatural that M. Poincaré should have given special prominence to the writings of his own countrymen; his treatise would, however, have been much improved had he not confined himself so exclusively to the writings of French mathematicians, but had given a fuller account of the work done by mathematicians of other nationalities. A. B. BASSET.

THE MOTHS OF INDIA.

The Fauna of British India, including Ceylon and Burma. Published under the authority of the Secretary of State for India in Council. Edited by W. F. Blanford. "Moths." Vol. i. By G. F. Hampson. (London: Taylor and Francis, 1892.)

MR

R. HAMPSON is already favourably known to entomologists by his work on the "Lepidoptera Heterocera of the Nilgiri District," which forms Part viii. of the series of "Illustrations of typical specimens of Lepidoptera Heterocera in the collection of the British Museum." In the work before us he has undertaken a far more important task; nothing less than a descriptive handbook of the moths of India, which, when complete, will prove as useful to Indian entomologists as the wellknown work on the butterflies of India by Marshall and De Nicéville.

Hitherto the available information on the moths of India has been scattered over a great variety of books and periodicals, far too numerous and costly to be easily available out of London or Calcutta, and extremely difficult to use satisfactorily, even if accessible. But Mr. Hampson has been given the fullest facilities for examining all the principal public and private collections of Indian moths, from that of the British Museum downwards, and has also made free use of the libraries of the British Museum at South Kensington, which now contain the finest series of entomological books in the world; and the result is a work which can hardly fail to give an enormous impetus to the collection and study of Indian moths.

Much attention has been paid to the classification of moths, and the introductory pages are occupied with details of structure, illustrated by woodcuts of parts of the head, antennæ, legs, and neuration. This is followed by a genetic tree of the families of moths, and by a

sophy and science. Mr. Steele has done his work much tact and care, and an interesting preface is ibuted by Mr. William Morris.

as

nomy for Every-day Readers. By B. J. Hopkins, R.A.S. (London: George Philip and Son, 1893.) is a little book which aims at explaining in rate and interesting a manner as possible such of the omena of the heavens as should be known to every igent person." It consists of six chapters dealing ctively with day and night, the phases of the moon, ides, the seasons, eclipses, meteors, shooting stars, comets. Descriptive astronomy is not touched upon, there is an introductory chapter giving a general y of the solar system and its dimensions. The book been very carefully written, and the scientific exations are much relieved by interesting references to istory of the subject. The author has succeeded in g very clear and concise accounts of the every-day omena with which the book specially deals, and it is well adapted to awaken a desire for more in the of readers to whom he more particularly appeals. ography of the author-who is described as "the ing-man scientist "-is also included.

LETTERS TO THE EDITOR.

Editor does not hold himself responsible for opinions exressed by his correspondents. Neither can he undertake o return, or to correspond with the writers of, rejected nanuscripts intended for this or any other part of NATURE. No notice is taken of anonymous communications.]

Blind Animals in Caves.

an article in the current number of the Contemporary Mr. Herbert Spencer discusses the "familiar instance" nd animals in caves as bearing upon the hypothesis of ransmission of acquired characters. Mr. Spencer is not ied with the explanation of the blindness of these cave als offered by Weismann, who endeavours to account for by two conditions recognised as operating in regard to cases by Darwin, viz. cessation of selection and mony of growth ("Origin of Species," sixth edition, 18), of which the former author has treated under lame Panmyxia. Mr. Spencer shows that the saving of erable material in the suppression of an eye is but a small my: he loses sight of the fact, however, that possibly, or probably, the saving to the organism in the reduction of an o a rudimentary state is not to be measured by mere bulk, by the non-expenditure of special materials and special ities which are concerned in the production of an organ so liar and elaborate as is the vertebrate eye.

at, however, to which I wish here to draw the attention of Mr. cer and his readers is this:-Mr. Spencer appears to think if he disposes of Weismann's explanation of the blindness ave animals according to "Panmyxia"-there remains the explanation by "transmission of acquired characters" e field. He appears not to be acquainted with the explana which I have offered of the blindness of cave-animals. It sely similar to that given by Darwin of the occurrence of less insects on oceanic islands. My explanation consists in pplication to the case in hand of Darwin's principle of tural selection." I published it some years ago in my article ology" in the "Encycl. Britannica," reprinted in 1890 in a me of essays, bearing the title "The Advancement of nce." My suggestion was (and is) as follows, and I should to see what Mr. Spencer has to say to it :-"This instance t of the blind cave-animals) can," I wrote in the article aboveed, "be fully explained by natural selection acting on contal fortuitous variations. Many animals are thus born with orted or defective eyes whose parents have not had their submitted to any peculiar conditions. Supposing a number ome species of Arthropod or Fish to be swept into a cavern be carried from less to greater depths in the sea, those induals with perfect eyes would follow the glimmer of light eventually escape to the outer air or the shallower depths, ing behind those with imperfect eyes to breed in the dark

place. A natural selection would thus be effected. In every succeeding generation (bred in the dark place) this would be the case, and even those with weak but still seeing eyes would in the course of time escape, until only a pure race of eyeless or blind animals would be left in the cavern or deep sea.'

My own position in regard to the hypothesis of the transmission of acquired characters remains what it was ten years ago, viz. that in the absence of observed instances of this transmission and in the presence of repeated observation that particular acquired characters are not transmitted, I do not consider it legitimate to assume a transmission of acquired characters as the explanation of any given case, such, for instance, as that of the blind cave-animals. I am confirmed in this attitude by the fact that a little consideration has enabled me and others to explain satisfactorily, by reference to no hypothetical causes, but to the admitted and demonstrable facts of "congenital variation and " "natural selection," instances brought forward as "only to be explained on the assumption of the truth of Lamarck's hypothesis."

On the other hand, I have always considered that there is not sufficient ground for asserting that a transmission of acquired characters can not take place. The important question is still as it was five years ago, "Does it take place?" Oxford, February 14. E. RAY LANKEster.

Glacier Action.

I HAVE read with great interest and pleasure the short review in your paper of last week by Prof. Bonney, giving a summary of the results of a survey of the French freshwater lakes, and indicating as the most probable conclusion that they cannot be accounted for on the theory of the late Sir A. Ramsay, by the digging out power of glaciers.

Living as I do in a highly glaciated country, and in a country also full of lakes, both fresh and salt, I have never believed in that theory. Lakes seem to me to be due to the same causes which have produced the glens and hollows in which they lie, and these causes cannot be identified with glacier action alone. The theory of Ramsay attributes to glacier action powers and effects which have never been proved to belong to them. Glaciers do not dig out. They rub down-abrade-and scoop, when they are moving down inclined planes at angles more or less steep. But when they reach level ground they do not dig; they rest upon the level surfaces, and when pressed from behind they flow over it. But I have never seen any proof that they can act like a ploughshare, or rather like one of the new digging machines.

In so far as all existing glens may have been formerly occupied by glaciers, their depths must have been increased by glacier action, on the supposition that they were tilted, or upraised at some angle required for this form of true glacier action. On this supposition, indeed, lake basins may be said to be partly due to glaciers. But then this supposition involves and depends upon the assumption that earth movements have made the lake basins what they now are-hollows in a comparative level.

Like all other general theories in the history of geology, the "glacial theory" seems to me to have been ridden to the death, and I have been long waiting for some signs of that reaction or correction which is still much needed. I hold that in this country there is not only no evidence of "ice sheets" overriding all the hills, but the strongest evidence against such sheets. Our glens had true glaciers in abundance, no doubt, and they have left their tool-marks very distinctly. But those marks are quite inconsistent with one universal ice-cap or ice-sheet over all the land. Inveraray, February 16.

ARGYLL.

Dr. Joule's Thermometers. EVERY one will, I am sure, be glad to know that Dr. Joule's thermometers are under investigation by Prof. Schuster.

It is unfortunate that Joule does not give the actual readings of the freezing point, but if the comparison quoted by Rowland was made in either 1879 or 1890 it may be that he referred to the reading of November, 1879, when the total rise of the zero point was 12'92 scale divisions. In that case the original reading in April, 1844, would be 9.70; at any rate this number cannot be very far from the truth.

The temporary changes of zero point alluded to by Prof. Schuster certainly complicate the matter, but from the numbers given it would appear that since 1879 or 1880 there has been a