expression, and would be identical with it if P = $ 0.00186 atmospheres. In that case the internal pressure due to the salt in a solution containing 20 parts of salt to 100 of water would be about the same as the internal pressure in pure water as given by Van der Waals. If, however, we attempt to apply van 't Hoff's theory of the pressure due to dissolved substances, we find, as in the examples quoted in the "Applications" (loc. cit.), that the observed values of PA' are many times greater than those given by calculation. The second Report, by Mr. Buchan, on "Atmospheric Circulation," of which we shall give some account in a future number, is rather a treatise on meteorology than a simple discussion of the Challenger observations. All the data, other than those derived from the expedition (which have been previously published), are set forth, and a vast collection of meteorological facts from all parts of the world is utilized. It would be impossible to attempt to discuss Mr. Buchan's conclusions in detail, but one may be selected as an example. Twenty-six thunderstorms occurred at sea during the voyage, and of these only four took place between 8 a.m. and 10 p.m. Nineteen occurred when the ship was near the land, and these were pretty evenly distributed throughout the twenty-four hours. Over land thunderstorms are most frequent during the day. At sea thunderstorms are nocturnal, and occur chiefly during the morning minimum of pressure. "Over the land the maximum of thunderstorms occurs during the hours of the day when temperature is the highest, but over the open sea during those hours when temperature is lowest. The great majority of thunderstorms over the land thus occur during the part of the day when the ascensional movement of the air from the heated surface of the ground takes place" (p. 32). These facts furnish Mr. Buchan with an interesting suggestion as to the cause of these differences : "As regards thunderstorms over the land surfaces of the globe, the disturbance of atmospheric equilibrium, resulting in ascending and descending currents, is brought about mainly by the superheating of the surface and thence of the lowermost strata of the air. But as regards the open sea, this mode of disturbing the atmospheric equilibrium cannot take place, inasmuch as the influence of solar radiation is only to raise the temperature of the surface of the sea not more than a degree. Hence it is probable that the disturbance of the equilibrium of the atmosphere, in the case of thunderstorms over the open sea, is brought about by the cooling of the higher strata of the atmosphere by terrestrial radiation” (p. 34). There can be little doubt that Mr. Murray is right in thinking that Mr. Buchan's Report will be a standard work of refere ce for many years to come. The third Report, by Commander Creak, is on the Magnetical Results of the voyage. As the author has himself described the main results of his investigations in the pages of NATURE, it is unnecessary to do more than refer to its most salient features. We have two, and only two criticisms to make. Commander Creak has employed the British unit of force, and his paper will therefore be used with less comfort and ease by most magneticians than if he had employed the C.G.S. system. Perhaps, however, as an Admiralty official he felt bound to adhere to the traditions of his office. Again, we think that he has been rather too modest in the amount of space he has claimed. Like Mr. Buchan, he has used information from many sources which are not, or at all events are not stated to be, generally accessible. These he has employed in determining the rates of secular change during the last 40 years all over the globe. It would have been interesting if means could have been devised for showing not merely the results of this investigation but the data on which they are based. Again, the map in which the direction of motion-eastward or westward-of the north pole of the needle is graphically shown for the period considered would have been more valuable if the magnitudes of the mean annual motion at different places had been added. This has, in fact, been done in a recent German work on the same subject. But if we are inclined to wish that Commander Creak had claimed a larger share of space and given more details, in what he has done he has gone beyond any previous writer. His work is of the highest importance as introducing a novel view of the causes of secular magnetic change, and in connecting it with certain definite localities. Mr. Buchan has furnished us with new meteorological maps. Commander Creak has prepared new magnetic maps, which enable us to institute a comparison between the magnetic state of the globe in 1880 and its condition when Sabine portrayed it for an epoch some 40 years earlier. The positions of the magnetic poles and foci of maximum intensity do not appear to have altered. The secular change is associated, not with these, but with four points, towards two of which the north pole of the needle is veering, and from two of which it is apparently being repelled. The points of increasing attraction on the north-seeking pole are to the south of Cape Horn and in the south of China; the foci of diminishing attraction are in the Gulf of Guinea and near the north magnetic pole in Canada. The existence of this last focus is more or less hypothetical, but in the case of the other three the various magnetic elements concur in indicating the same neighbourhood as the centre of change. Thus not only is the secular variation of the declination of opposite signs to the east and west of these points, but the increase of the downward attraction on the north pole of the needle is a maximum near Cape Horn and in China, and a minimum (¿.e. a maximum decrease) in the Bight of Benin. Again the annual change of horizontal force is very small near Cape Horn, but it is decreasing in South America, and the rate of decrease is a maximum at a point between Valparaiso and Monte Video. These are precisely the kind of results which would follow from the gradual production of a subsidiary centre of relative attraction on the north-seeking pole of the magnet near Cape Horn. The real existence of the Gulf of Guinea centre is similarly confirmed. Commander Creak cautiously abstains from theorizing on these remarkable facts, but there can be no doubt that he is right in thinking that they must lead us to look for the chief causes of secular variation within the globe rather than in solar or extra-terrestrial influences. His paper will be a point of new departure in the science of terrestrial magnetism. It will be seen from what has been said that the three Reports which have been discussed are written with a wider scope than the mere discussion of the observations made during the voyage of the Challenger. Prof. Tait's paper has indeed little connection with the work of the Expedition. Mr. Buchan and Commander Creak have worked up an immense amount of matter derived from other sources. The records of the Challenger have not only added facts of great importance to our stock of knowledge; but have been, as it were, nuclei round which a host of other observations have crystallized into orderly arrangement. Each one of the authors has made a step forward. Prof. Tait has extended the range of pressure over which compressibilities have been measured. Mr. Buchan has attacked the diurnal climatology of the ocean. Commander Creak has given a new turn to our ideas on the secular change of terrestrial magnetism. It is only to be regretted that the exclusive use of British systems of measurement, and the other blemishes to which we have felt compelled to refer, give a certain insular appearance and character to a work of world-wide interest. The Report on the Rock-Specimens collected on Oceanic Islands, by Prof. A. Renard, consists of 180 pages, well illustrated by woodcuts and seven maps, and constitutes a very important part of the petrology of the Challenger Expedition. The account of the rocks of St. Paul's from the pen of Prof. Renard has already appeared in Vol. II. (Narrative), Appendix B, of the Challenger Reports, and we are glad to learn from the preface to the volume now before us that the "Report on DeepSea Deposits" which has been so long looked for by geologists, is to be issued next month. Mr. Murray is to be congratulated on having secured the services of so able a mineralogist and petrographer as Prof. Renard to describe the rocks brought home by the Expedition. Most of these descriptions have already appeared in the Bulletin of the Musée Royal d'Histoire Naturelle de Belgique; but English geologists will be glad to see them collected together and published in their own language, and in a convenient form for reference. Prof. Renard explains in his opening remarks the grounds for publishing this account of the rock-specimens collected on the oceanic islands by the officers of the Challenger Expedition : "Mr. Murray had discovered that loose volcanic materials played a very large part in the formation of the deposits of the deep sea, and it was considered desirable to institute a comparison between these and the products of the same origin in volcanic islands situated in or on the borders of the great ocean basins." It is at the same time admitted, by the editor of the volume, that Prof. Renard's lithological and mineralogical descriptions must be regarded rather as contributions to the geology of the islands visited, than as supplying full and descriptive discussions of the subject. "The necessities of the voyage, bad weather, or the difficulties of the exploration, prevented, in many cases, the naturalists from passing more than an hour or two on shore; they were thus unable to give any detailed account of the stratigraphical relations, and the collections of hand-specimens were sometimes limited to those rocks situated near the coast." In the case of Tenerife, of which we have such full descriptions in the writings of Von Fritsch and Reiss, and of Sauer; in that of the Cape de Verde Islands, the | rocks of which have been carefully studied by Dolter; and of Fernando Noronha, which has been surveyed and its rocks admirably described by Profs. Branner and Williams, it is obvious that the description of the specimens placed in the hands of Prof. Renard can only be regarded as supplementary to the fuller and more comprehensive accounts of the geology of the islands which we already possess. But in the case of some of the smaller islands. like Tristan da Cunha, Marion Island, and Heard Island, the notes in the present Report constitute almost the only materials which exist for judging of their geological constitution and structure. In the case of the Island of St. Thomas, in the West Indies; of Kandavu, in Fiji; of the volcano of Goonong Api, in the Banda Islands; of the volcano of Ternate, and of several islands in the Philip pine Group, Prof. Renard has taken the opportunity afforded to him by the receipt of interesting specimens casually collected, to discuss points of considerable mineralogical and geological interest. Quite apart from their connection with certain localities, these very careful notes of Prof. Renard on peculiarities exhibited by rock-forming minerals are of much value to geologists; and so also are the series of analyses of these rock-specimens, made, evidently with great care, by Dr. Klement. So many of the islands visited by the Challenger were previously touched at by the Beagle, on board of which Charles Darwin was acting as naturalist, that it is impossible to avoid comparing the work before us with that author's classical memoir, "Geological Observations on the Volcanic Islands," which was published in 1844 and re-issued in 1876. In spite of the improvements of our petrographical methods during the half-century, which has witnessed the application of the microscope to the study of rocks, it is very interesting to see how often observations made by Darwin, aided by that great pioneer in crystallographic research, Prof. W. H. Miller of Cambridge, are confirmed by the painstaking labours of Prof. Renard. There is, perhaps, some danger, at the present day, that the facilities afforded for the microscopic study of rocks, by the aid of transparent sections, should lead geologists and mineralogists to despise, or to regard as of small value, the observations made without such aid. To those who entertain such an idea, it will be instructive to see how Darwin and Miller by the aid of pocket-lens, knife-blade, and magnet, were often able to form an appreciation of the mineralogical constitution of rocks, which has been very largely confirmed by the application of the more refined methods of the present day. The discussion of great geological problems, which, as treated by Darwin in 1844, contributed so largely to the interest excited by his book, have of course not come within the scope of the work undertaken by Prof. Renard. The particular varieties of volcanic rocks in Ascension, which Darwin found to illustrate in so striking a manner the origin of foliation in the crystalline schists, do not seem to have been among those collected by the officers of the Challenger. But as an important contribution to micropetrography, the work of Prof. Renard is of the highest value, as might indeed have been anticipated from the well-proved skill and acumen of the author m this interesting branch of scientific research. THE HUMAN FOOT. The Human Foot: its Form and Structure, Functions and Clothing. By Thos. S. Ellis. (London: J. and A. Churchill, 1889.) THIS HIS book is an endeavour on the part of a practical surgeon to explain the mechanical construction of the human foot, and from this basis to show the principles on which boots and shoes ought to be constructed. Although written in a popular form, and intended for the instruction of the public, it is treated in a scientific spirit by one who is competent, on the ground of anatomical knowledge, to discuss the subject. Mr. Ellis was led to give special attention to the mechanism of the foot owing to one of his feet having been accidentally injured; and his recovery from lameness was due to the independent study which he was obliged to give to the structure of the foot in relation to its functions. than the first, but in the left foot the opposite is the case. In an Australian boy, aged 4, in the right foot the great toe is slightly the longer, but in the left foot the second toe has the advantage. In none of these Australians had the feet ever worn shoes, so that the variation in the length of these toes is natural, and not produced by artificial means. It would appear, therefore-as was shown several years ago by Prof. Ecker, of Freiburg, and by a writer in NATURE, to be the case in the hand with the ring and index finger-that variations in relative length may occur, not only in different individuals, but in opposite limbs in the same person. The author then discusses the movements at the joints of the foot and the action of the muscles; more especially when the heel is raised and the foot rests on tip-toe as in the movements of progression. He regards the long flexor of the hallux as exercising a bow-string or tie-rod influence, bracing up the arch and diminishing the distance between the heel and the great toe. Hence the exercise of dancing is one of the most important means of promoting and maintaining the strength of the foot. As regards the act of walking, Mr. Ellis contends that what he calls the "four-square position," in which the inner borders of the great toes are retained almost parallel to each other, is that which is most conducive to steady and continuous progression, for the joints and muscles of the foot obtain through it momentary rest in the intervals between the steps. He condemns the military position, with the toes turned outwards, both in standing and walking, as much more fatiguing, by keeping the muscles and joints in a constant strain. The condition of The earlier pages of the book are occupied by a short but clearly-written description of the form of the foot, and of so much of its anatomy as is needed to explain its mechanism. In the course of this description the author points out that the two feet are to be considered together, not as if they were two independent pedestals, or plinths, supporting the lower limbs and body, but as the two halves of one pedestal or plinth, the divisions of which are separated from each other. He recognizes the inner margin of the foot in its front or expanded part as forming a straight line, whilst the outer margin forms a bold curve, and acts as a sort of buttress to the main structure of the foot. The inner margin also is elevated to form the arch of the instep. He refers to Prof. Meyer's well-"flat-foot" ought never to arise if the tie-rod action of known line continued backwards from the mid-line of the great toe through a central point of the heel which follows the line of the long flexor of the great toe, and states that this line corresponds with the highest part of the ridge on the dorsum or upper surface of the foot, which indicates the course of the long extensor of the great toe. The importance of the great toe in the construction of the foot is dwelt upon by Mr. Ellis. He shows that, when the foot is used as the basis from which the body is to be propelled forwards in the act of progression, the great toe leaves its fellows and passes towards the mesial plane between the two feet, but that it is not bent in so doing. On the other hand, the smaller toes, whilst being pressed against the ground, become bent, and the phalangeal joints are lifted upwards. The relative length of the great and second toes is also discussed. As is well known, in many of the statues of ancient art the second toe is modelled somewhat longer than the great toe, but as a rule in nature itself the great toe is the longer. Exceptions, however, occasionally occur. The writer of this notice has now before him the casts of two well-formed feet, from a man and a woman, in both of which the second toe projects beyond the great toe. He has also in his possession casts of the feet of several of the aborigines of Australia, taken under the superintendence of Prof. Anderson Stuart, of the University of Sydney, in which interesting variations in the relative length of these toes may be seen. In a man and one woman the great toe is longer than the second; in another woman the second toe in the right foot is longer the long flexor muscles of the toes be sufficiently exercised by frequent springing of the foot to tip-toe, such as takes place in the act of dancing. The author applies the anatomical principles which he has expounded to the construction of stockings and shoes. He holds that quite as much mischief is done to the feet by wearing ill-made socks as badly-shaped shoes. He considers that a stocking with a separate stall for the great toe is always desirable, but that a straight inside line is imperative. To obtain a properly fitting boot it is necessary, in addition to the measures of length and girth, to have the contour lines of the foot, and to obtain these the author has devised a foot-stand or pedistat, a description and figure of which are given in the book. From these measures a last can be made which conforms to the shape of the foot throughout as it stands on a level surface. We recommend the perusal of this book to all who are interested in the mechanism of the foot, and in obtaining for it well-fitting socks and shoes; and we do so with the more confidence as the author had obviously passed through a painful experience before he had satisfied himself of the principles which ought to be attended to in the construction of its clothing. OUR BOOK SHELF. Das australische Florenelement in Europa. Von Dr. THIS is a defence of the identification of fossil plants from Hungary, with existing Australian genera. Baron Ettingshausen himself is largely responsible for these identifications, which have been questioned "by certain critics insufficiently acquainted with the subject." He claims that he was supported in his views by such eminent palaeontologists as Franz Unger and Oswald Heer. It is now some years since Unger published his sensational "Neuholland in Europa." In this little work almost every one of a set of Eocene fossil plants is identified with some essentially Australian genus, and often, we should add, on the very slenderest of material. The late Mr. G. Bentham, who, as is well known, handled and described every Australian plant of which specimens had been collected up to his time, disputed the correctness of the identifications, and endeavoured to prove that the remains might well be those of genera still found in the northern hemisphere; yet Baron Ettingshausen gives us to understand that Mr. Bentham confirmed his determination of a European fossil leaf as belonging to the genus Dryandra. Quite recently the Marquis de Saporta has attacked probably have paid so much attention to the venation Is the Copernican System of Astronomy True? By W. AN astronomer nowadays would find it a hard task to We have already said enough to show that the book need not be considered seriously; but we cannot refrain from stating that the author, by sighting the sun along straight-edges at the equinoxes, has found that "the distance of the sun from the surface of the earth, at 40° N., is one million miles (p. 49)." This result is about as near the mark as could be expected from the method employed. Naturalistic Photography. By P. H. Emerson, B.A., THE quick call for a second edition of this work indicates us. safely say there is not a better or more instructive book on the art principles of photography than the one before Dr. Emerson is a photographer of the first rank, his artistic compositions are everywhere admired, and the energetic manner with which many of the old and cherished ideas of the ordinary photographer are attacked and others established makes it very manifest that he only writes what he knows to be true. The literary style of the book is excellent, and the exposition has the merit of being strikingly original; it should, therefore. be studied by every photographer, both amateur and professional, who desires to excel in his art. LETTERS TO THE EDITOR. [The Editor does not hold himself responsible for opinions expressed by his correspondents. Neither can he undertaki to return, or to correspond with the writers of, rejected manuscripts intended for this or any other part of NATURE, No notice is taken of anonymous communications.] Acquired Characters and Congenital Variation, BEYOND this letter I cannot pursue my interpolated adversary. Mr. Dyer. The syllogisms which he attributes to me are entirely his own. I willingly admit, therefore, that they are as ingeniously bad as they can well be. I will now state shortly what my position was, and is :(1) The assumed antithesis between "acquired characters' and "congenital variation" has arisen out of the cult of Darwin as opposed to Lamarck. (2) The theory of Lamarck fails, in my opinion, as much a the theory of Darwin, to give any adequate or satisfying explana tion either of the genesis, or of the development, of organic forms. (3) But the theory of Lamarck is more philosophical than the theory of Darwin, in so far as it seeks for, and specifies, a definite natural cause for the phenomena of variation. (4) The theory of Darwin is essentially unphilosophical in so far as it ascribes these phenomena to pure accident, or fortuity (5) That Darwin himself, at one time, if not always, admitted this idea of fortuity to be a mere provisional resort under the difficulties of ignorance. (6) That the later worshippers of Darwin depart, in this respect, from their master, and making the weakest part of his system the special object of their worship, have set up Fortaity as their idol. (7) That it is under the influence of this superstition that they now seek to deny altogether that acquired characters can become congenital. (8) That this denial is against the most familiar experience of Nature, and especially of artificial selection, which is the antetype and foundation of the whole theory of evolution. (9) That in all domestic animals, and especially in dogs, we have constant proof that many acquired characters may become congenital. (10) That it is no answer to this argument to demand proof that the babies of a blacksmith are ever born with the abnormal arm-muscle of their papa. (11) That in order to avoid and evade the force of innumerable facts proving that many acquired characters may, and do, become hereditary, fortuitists have invented a new verbal definition ul what they mean by "acquired.' (12) That this definition is full of ambiguities and assumptions, concealed under plausible words, but the object of which is to limit the meaning of "acquired characters' to gross, visible, palpable changes affecting single individuals, and which the analogies of Nature do not lead us to expect or to suppose can be repeated in a single generation, even if a tendency to their development is really implanted in the race. (13) That, still farther to render impossible the proof they demand, our fortuitists affix to their definition of the word "acquired," conditions which beg the whole question in dis pute. Not only must the new characters be gross, palpable, visible-cases of "hypertrophy," of "extension," or of "thick ening," but also they must be "obviously due to the direct physical action of the environment on the body of the individual.' This is a condition which is irrational. It excludes all those fine, invisible "molecular" changes, through which Nature habitually works, and it ascribes to mere outward and mechanical agencies, effects which, alone, we have no reason to suppose they ever can produce. On the question of "prophetic germs," Mr. Dyer challenged me to produce a single case of organs useless now, but in course of preparation for future use. I replied by referring him to this phenomenon as universal throughout Nature in the life-history of every individual organism; and I also referred him to the well-known idea of Darwinian embryology which establishes a close analogy between the laws governing the development of the embryo, and the whole past development of organic life. Mr. Dyer replies that I ought to have explained this soonerwhen challenged to do so by Prof. Ray Lankester-an observation which has nothing to do with the merits of the question. The truth is, I wished to close my dispute with that distinguished Professor, as I now desire to close it with Mr. Dyer, and I was satisfied with an indirect admission that, as regards every individual organism, my assertion could not be contradicted. What this involves, I left, and now leave again, as unexhausted as it is indeed inexhaustible. In conclusion, I must observe upon the use Mr. Dyer makes of the phrase "a priori argument," which he apparently uses not only for all deductive argument, but for all analytical reasoning. When he says he has not an a priori mind," he really means that he is indisposed to all analysis. This is a very com. mon attitude even with many able and distinguished men--especially when they are devoted to a system, and are the disciples of some prophet, whose words and phrases they gulp and swallow whole. It is an attitude which has its use; but it is not one to boast of Mr. Dyer's declaration that "the questions at issue with regard to evolution are now, I believe, thoroughly understood by biologists "is the most astonishing utterance I have ever heard or read coming from a scientific man. Discussion with him is useless. He and his friends know all about it. How life began, and how it grew from more to more-the whole secret of creation-"an open scroll, before them lies." I am happy to think that I am not the only searcher-by many housands-whose pens Mr. Dyer must intervene to stop. There is a great army of us who are conscious above all things of the ignorance of man. Kinellan, Murrayfield, N. B. ARGYLL. In the number for January 16 (p. 247) Mr. Thiselton Dyer observes that "there are many readers of NATURE who, while taking a general interest in the problems raised by Darwinism, have not followed all that has been written about it." For the benefit of such persons he gives an interesting explanation of Darwin's views on several important points. I have not read all that has been written, but all, I think, that has ever appeared in the pages of NATURE, and with the result that I am more and more convinced of the inadequacy of the Darwinian theory to account for the origin of species. Natural selection is a era causa, but of very limited operation. The theory of sexual selection but partly removes one serious difficulty not of the first magnitude. I find! Darwinians-not Darwin-very ready to insinuate or assert that an unwillingness to adopt their views, on the part of persons who believe in a supernatural revelation, arises from theological prejudice, which hinders them from listening to the voice of reason. I think there is some prejudice on both sides. For myself, fully believing in a Supreme Designer, I am perfectly and most fearlessly willing that the attempt at mechanical explanation" should be carried as far as possible, well knowing that a final universal cause" cannot possibly be disproved or reasonably denied. And Darwinism is committed to no such denial. Life on We have our choice between two alternatives. our globe had a beginning; and its cause was certainly not mechanical or natural,-for reasons not theological, but strictly scientific, in the technical sense of the word. For, as the laws of Nature operate uniformly, if life had ever commenced spontaneously, it must of natural necessity do so again and again, since it would be most absurd to suppose that only during some previous state of the earth's surface did matter exist m such a condition as to be capable of conversion into living things. If life had ever arisen mechanically, it would require a miracle to prevent repetitions of the process. We have, then, to take our choice between supposing with Darwinians that the life-producing power acted once for all, and supposing that it has acted repeatedly and continuously, in more ways than one. I see no theological, and, let me say, no Scriptural, objection to either. Let it be believed willingly, if good reasons can be given, that all life began with a single germ which could not only produce its like-which is wonderful enough-but which even contained in itself such amazing potentialities that it could become, and has become, the parent of every form of life, sentient or non-sentient, that has ever appeared on our globe. To me this seems scientifically improbable. For why should the power, whether acting intelligently, or, if anyone prefers it, without intelligence, create one germ only? Why not millions? And if of one kind, why not of many? And if single organisms, why not organisms connected with one another, even in highly complex structures? And why act once only? Why not start non-sentient life at one time, sentient at another? For do not sentient things need a separate germ? I take leave to think so. But be this as it may, they are as much in advance of the nonsentient, however much alike those germs we know of may appear to be, as the non-sentient are of inanimate matter. The other alternative supposition is that the life-producing power, instead of acting once only, and then subsiding into its primæval torpor, continues to act. That, as it once acted upon inanimate matter, not robbing it of anything, but rather, while availing itself of its properties, conferring upon it new powers, so it has acted since upon living things, ever producing out of the old new and higher forms of life; availing itself of all existing faculties of living things, but while allowing them to achieve all that they can, still moulding fresh forms, and conferring higher faculties. To suppose this, is only to suppose that the action of the life-producing power, since life began, has been analogous to what we know was its action in producing life. It is hardly to be supposed that the production of one marvellous germ has exhausted all its energy. Yet, if the Darwinian theory can enable us to dispense with the aid of this power, let it do so. Let reason prevail. Darwinians offer, as an adequate explanation of the formation of new species from the older, that this development comes about simply through natural selection-through the survival of the fittest of favourable variations. 66 No The origin of any species," says Mr. Thiselton Dyer, "lies firstly in the occurrence, and secondly in the selection and preservation, of a particular variation.' But surely a particular variation alone-that is, such as can be brought about, as we know from experience, in a single generation-does not sufficiently differentiate one species from another. Short-horned cattle, for instance, are not a new species, nor would they deserve to be so termed if it should eventually happen that all other varieties of horned cattle became extinct. In the great majority of cases, at all events, there must be more than one particular variation, before we can recognize a specific difference. Species have become what they are by the combination, in one organism, of many particular variations, each well suited to the rest. particular variation could make of another ruminant a giraffe. What we want, and what seems to be wanting in the Darwinian theory, is a satisfactory hypothesis to explain the concurrence of many particular variations, by the co-existence of which in one structure the new species is constituted. Variations, or “fluctuations," as Mr. Thiselton Dyer has happily termed them, will not account for this. Between some species there may be merely slight and single differences; but Nature can show us much more than this. We often find a complicated apparatus formed by the concurrence in one individual of many particulars of structure combining to produce an effect wholly peculiar. Take the following instance, or rather group of instances. There are venomous serpents, of many species and in many lands, which differ most widely from the non-venomous kinds, from which, or from the ancestors of which, they are generally believed to have been derived. In these we find, to begin with, teeth which have undergone strange modifications. They are needle-like in shape. They are not fixed in the jaw. They occupy a very prominent position. They have minute perforations, terminating near, but not precisely at, the point. They have muscles by which they may be recurved, so that their points may be directed towards the throat. They have hollows in which to lie. They have muscles by which, on occasions, they may be projected beyond the mouth. Besides all this poison-secreting glands, and poison-bags, and channels of com |