L €SGGGL100 LOLI Digitized by the Internet Archive in 2007 with funding from Microsoft Corporation http://www.archive.org/details/fiftyyearsofscieOOlubbuoft it te ti ee ee a FIFTY YEARS OF SCIENCE BEING THE ADDRESS DELIVERED AT YORK TO THE BRITISH ASSOCIATION AUGUST 1881 BY SIR JOHN LUBBOCK, BART., M.P. wr PRESIDENT OF THE ASSOCIATION Zondon MACMILLAN AND CO. : 1882 ADDRESS TO THE BRITISH ASSOCIATION, 1881. In the name of the British Association, which for the time I very unworthily represent, I beg to tender to you, my Lord Mayor, and through you to the City of York, our cordial thanks for your hospitable invitation and hearty welcome. We feel, indeed, that in coming to York we are coming home. Gratefully as we acknowledge, and much as we appreciate the kindness we have ex- perienced elsewhere, and the friendly relations which exist between this Association and most—I might even say, all—our great cities, yet Sir R. Murchison truly observed at the close of our first meeting in 1831, that to York, ‘as the cradle of the Association, we shall ever look back with gratitude ; and whether we meet here- after on the banks of the Isis, the Cam, or the Forth, to this spot we shall still fondly revert.’ Indeed, it would have been a matter of much regret to all of us, if we had not been able on this, our fiftieth anniversary, to hold our meeting in our mother city. My Lord Mayor, before going further, I must ex- press my regret, especially when I call to mind the B 2 ADDRESS TO THE BRITISH ASSOCIATION, 1881. illustrious men who have preceded me in this chair, that it has not fallen to one of my eminent friends around me, to preside on this auspicious occasion. Conscious, however, as I am of my own deficiencies, I feel that I must not waste time in dwelling on them, more especially as in doing so I should but give them greater prominence. I will, therefore, only make one~ earnest appeal to your kind indulgence. The connection of the British Association with the City of York does not depend merely on the fact that our first meeting was held here. It originated in a letter addressed by Sir D. Brewster to Professor Phillips, — as Secretary to your York Philosophical Society, by whom the idea was warmly taken up. The first meet- ing was held on September 26, 1831, the chair being occupied by Lord Milton, who delivered an address, after which Mr. William Vernon Harcourt, Chairman of the Committee of Management, submitted to the meeting a code of rules which had been so maturely considered, and so wisely framed, that they have remained substantially the same down to the present day. Of those who organised and took part in that first meeting, few, alas! remain. Brewster and Phillips, — Harcourt and Lord Milton, Lyell and Murchison, all have passed away, but their memories live among us. Some few, indeed, of those present at our first meeting, we rejoice to see here to-day, including one of the five — members constituting the original organising Com- mittee, our venerable Vice-President, Archdeacon — Creyke. The constitution and objects of the Association were — THE PROGRESS OF SCIENCE. 3 ‘$0 ably described by Mr. Spottiswoode, at Dublin, and ‘are so well known to you, that I will not dwell on them this evening. The excellent President of the Royal ‘Society, in the same address, suggested that the past’ history of the Association would form an appropriate ‘theme for the present meeting. The history of the Association, however, is really the history of science, ‘and I long shrank from the attempt to give even a ‘panoramic survey of a subject so vast and so difficult ; nor should I have ventured to make any such attempt, but that I knew I could rely on the assistance of friends in every department of science. Certainly, however, this is an opportunity on which it may be well for us to consider what have been the principal scientific results of the last half-century, dwelling especially on those with which this Associa- tion is more directly concerned, either as being the work of our own members, or as having been made known at our meetings. I have, moreover, especially taken those discoveries which the Royal Society has deemed worthy of a medal. It is of course impossible within the limits of a single address to do more than allude toa few of these, and that very briefly. In dealing with so large a subject I first hoped that I might take our annual volumes as a text-book. This, however, I at once found to be quite impossible. For instance, the volume commences with a Report on Astronomy, by Sir G. Airy ; I may be pardoned, I trust, for ex- my pleasure at finding that the second was one by my father, on the Tides, prepared like the pre- c at the request of the Council; then comes one Meteorology by Forbes ; Radiant Heat, by Baden B2 4 ADDRESS TO THE BRITISH ASSOCIATION, 1881. Powell ; Optics, by Brewster ; Mineralogy, by Whewell, and so on. My best course will therefore be to take our different Sections one by one, and endeavour to bring before you a few of the principal results which have been obtained in each department. The Biological Section is that with which I have been most intimately associated, and with which it is, — perhaps, natural that I should begin. io Fifty years ago it was the general opinion that animals and plants came into existence just as we now see them. We took pleasure in their beauty ; their adaptation to their habits and mode of life in many — cases could not be overlooked or misunderstood. — Nevertheless, the book of Nature was like some richly illuminated missal, written in an unknown tongue. — The graceful forms of the letters, the beauty of the — colouring, excited our wonder and admiration ; but of — the true meaning little was known to us; indeed we scarcely realised that there was any meaning to decipher. Now glimpses of the truth are gradually revealing themselves ; we perceive that there is a reason—and in many cases we know what that reason is—for every difference in form, in size, and in colour ; for every bone and every feather, almost for every hair. Moreover, each problem which is solved opens out vistas, as it were, of others perhaps even more interesting. With this impor- tant change the name of our illustrious countryman, Darwin, is intimately associated, and the year 1859 will always be memorable in science as having produced his work on ‘ The Origin of Species.’ In the previous year he and Wallace had published short papers, in which BIOLOGY. THE DARWINIAN THEORY. 5 they clearly state the theory of natural selection, at which they had simultaneously and independently arrived. We cannot wonder that Darwin’s views should have at first excited great opposition. Never- theless from the first they met with powerful support, especially, in this country, from Hooker, Huxley, and Herbert Spencer. The theory is based on four axioms :— ‘1. That no two animals or plants in nature are identical in all respects. £2, That the offspring tend to inherit the peculiar- ities of their parents. ‘3. That of those which come into existence, only a small number reach maturity. ‘4. That those, which are, on the whole, best adapted to the circumstances in which they are placed, are most likely to leave descendants.’ Darwin commenced his work by discussing the causes and extent ot variability in animals, and the origin of domestic varieties ; he showed the impossibility of distinguishing between varieties and species, and pointed out the wide differences which man has pro- duced in some cases—as, for instance, in our domestic pigeons, all unquestionably descended from a com- mon stock. He dwelt on the struggle for existence ‘(since become a household world), which, inevitably resulting in the survival of the fittest, tends gradually to adapt any race of animals to the conditions in which it occurs. While thus, however, showing the great importance of natural selection, he attributed to it no exclusive in- fluence, but fully admitted that other causes—the use 6 ADDRESS TO THE BRITISH ASSOCIATION, 1881. and disuse of organs, sexual selection, &c.—had to be taken into consideration. Passing on to the difficulties of his theory, he accounted for the absence of inter- — mediate varieties between species, to a great extent, by — the imperfection of the geological record. Here, how- — ever, I must observe that, as I have elsewhere remarked, those who rely on the absence of links between different — species really argue in a vicious circle, because wherever such links do exist they regard the whole chain as a single species. The dog and jackal, for instance, are now regarded as two species, but if a series of links — were discovered between them they would be united — into one. Hence in this sense there never can be links — between any two species, because as soon as the links are discovered the species are united. Every variable — species consists, in fact, of a number of closely connected ~ links. But if the geological record be imperfect, it is still — very instructive. The further paleontology has pro- _ gressed, the more it has tended to fill up the gaps between existing groups and species: while the careful — study of living forms has brought into prominence the variations dependent on food, climate, habitat, and other — conditions, and shown that many species long supposed to be absolutely distinct are so closely linked together by intermediate forms that it is difficult to draw a satis-— factory line between them. Thus the European and ~ American bisons are connected by the Bison priscus of Prehistoric Europe ; the grizzly bear and the brown bear, as Busk has shown, are apparently the modern representatives of the cave bear; Flower has pointed out the paleontological evidence of gradual modification” THE PRINCIPLES OF CLASSIFICATION. 7 of animal forms in the Artiodactyles ; and we may almost say, as a general rule, that the earliest known. -mammalia belong to less specialised types than our existing species. They are not well-marked Carnivores, Rodents, Marsupials, &c., but rather constitute a group of generalised forms from which our present well-marked orders appear to have diverged. Among the Inverte- brata, Carpenter and Williamson have proved that it is almost impossible to divide the Foraminifera into well- marked species ; and, lastly, among plants, there are large genera, as, for instance, Rubus and Hieracium, with reference to the species of which no two botanists are agreed. The principles of classification point also in the same direction, and are based more and more on the theory of descent. Biologists endeavour to arrange animals on what is called the ‘ natural system.’ No one now places whales among fish, bats among birds, or shrews with mice, notwithstanding their external simi- larity ; and Darwin maintained that ‘community of descent was the hidden bond which naturalists had been unconsciously seeking.’ How else, indeed, can we explain the fact that the framework of bones is so similar in the arm of a man, the wing of a bat, the fore- leg of a horse, and the fin of a porpoise—that the neck of a giraffe and that of an elephant contain the same number of vertebrae ? Strong evidence is, moreover, afforded by embryo- logy ; by the presence of rudimentary organs and tran- sient characters, as, for instance, the existence in the ealf of certain teeth which never cut the gums, the shrivelled and useless wings of some beetles, the presence 8 ADDRESS TO THE BRITISH ASSOCIATION, 1881. of a series of arteries in the embryos of the higher — Vertebrata exactly similar to those which supply the gills in fishes, even the spots on the young blackbird, — the stripes on the lion’s cub ; these, and innumerable — other facts of the same character, appear to be incom- — patible with the idea that each species was specially and independently created ; and to prove, on the contrary, — that the embryonic stages of species show us more or — less clearly the structure of their ancestors. Darwin’s views, however, are still much misunder- stood. I believe there are thousands who consider that — according to his theory a sheep might turn into a cow, or a zebra into a horse. No one would more confidently — withstand any such hypothesis, his view being, of course, not that the one could be changed into the other, but that both are descended from a common ~ ancestor. No one, at any rate, will question the immense im- pulse which Darwin has given to the study of natural — history, the number of new views he has opened up, and the additional interest which he has aroused in, and — contributed to, Biology. When we were young we knew that the leopard had spots, the tiger was striped, — and the lion tawny ; but why this was so it did not — occur to us to ask ; and if we had asked no one could — have answered. Now we see at a glance that the — stripes of the tiger have reference to its life among — jungle-grasses ; the lion is sandy, like the desert ; while the markings of the leopard resemble spots of — sunshine glancing through the leaves. Again, Wallace — in his charming essays on natural selection has shown how the same philosophy may be applied even to birds’ ~ EMBRYOLOGY. 9 nests—how, for instance, open nests have led to the dull colour of hen birds; the, only British exception being the kingfisher, which, as we know, nests in river- banks. Lower still, among insects, Weismann has taught us that even the markings of caterpillars are full | of interesting lessons ; while, in other cases, specially among butterflies, Bates has made known to us the curious phenomena of mimicry. The science of embryology may almost be said to have been created in the last half-century. Fifty years ago it was a very general opinion that animals which are unlike when mature, were dissimilar from the beginning. It is to Von Baer, the discoverer of the mammalian ovum, that we owe the great generalisation that the development of the egg is in the main a pro- gress from the general to the special, that zoological affinity is the expression of similarity of development, and that the different great types of animal structure are the result of different modes of development—in fact, that embryology is the key to the laws of animal development. Thus the young of existing species resemble in many eases the mature forms which flourished in ancient times. Huxley has traced up the genealogy of the horse to the Miocene Anchitherium, and his views have since been remarkably confirmed by Marsh’s dis- covery of the Pliohippus, Protohippus, Miohippus, and Mesohippus, leading down from the Eohippus of the early tertiary strata. In the same way Boyd-Dawkins and Gaudry have called attention to the fact that just as the individual stag gradually acquires more and morecom- plex antlers: having at first only a single prong, in the 10 ADDRESS TO THE BRITISH ASSOCIATION, 1881. next year two points, in the following three, and so on ; so the genus, as a whole, in Middle Miocene times, had — two pronged horns ; in the Upper Miocene, three ; and that it is not till the Upper Pliocene that we find any ~ species with the magnificent antlers of our modern deer. — It seems to be now generally admitted that birds have come down to us through the Dinosaurians, and, as — Huxley has shown, the profound break once supposed — to exist between birds and reptiles has been bridged — over by the discovery of reptilian birds and bird-like — reptiles ; so that, in fact, birds are modified reptiles. The — remarkable genus Peripatus, so well studied by Moseley, — tends to connect the unnulose and articulate types. | : Again, the structural resemblances between Am- phioxus and the Ascidians had been pointed out by Goodsir ; and Kowalevsky in 1866 showed that these were not mere analogies, but indicated a real affinity. These observations, in the words of Allen Thomson, ‘have produced a change little short of revolutionary in — embryological and zoological views, leading as they do ~ to the support of the hypothesis that the Ascidian is an — earlier stage in the phylogenetic history of the mammal ~ and other vertebrates.’ The larval forms which occur in so many groups, — and of which the Insects afford us the most familiar ex- — amples, are, in the words of Quatrefages, embryos, which — lead an independent life. In such cases as these, external - conditions act upon the larve as they do upon the — mature form; hence we have two classes of changes, — adaptational or adaptive, and developmental. These and many other facts must be taken into consideration 3 _ nevertheless naturalists are now generally agreed that — THE GASTRAZA THEORY. ll embryological characters are of high value as guides in classification, and it may, I think, be regarded as well- established that, just as the contents and sequence of ~ rocks teach us the past history of the earth, so is the gradual development of the species indicated by the structure of the embryo and its developmental changes. When the supporters of Darwin are told that his theory is incredible, they may fairly ask why it is im- possible that a species in the course of hundreds of thousands of years should have passed through changes which occupy only a few days or weeks in the life- history of each individual ? The phenomena of yolk-segmentation, first observed by Prevost and Dumas, are now known to be, in some form or other, invariably the precursors of embryonic develop- ment ; while they reproduce, as the first stages in the formation of the ‘higher animals, the main and essential features in the life-history of the lowest forms. The ‘ blastoderm,’ as it is called, or first germ of the embryo in the egg, divides itself into two layers, corresponding, as Huxley has shown, to the two layers into which the body of the Ceelenterata may be divided. Not only so, but most embryos at an early stage of development have the form of a cup, the walls of which are formed by the two layers of the blastoderm. Kowalevsky was the first to show the prevalence of this embryonic form, and sub- sequently Lankester and Haeckel put forward the hypo- thesis that it was the embryonic repetition of an ancestral type, from which all the higher forms are descended. ‘The cavity of the cup is supposed to be the stomach of this simple organism, and the opening of the cup the mouth. The inner layer of the wall of the cup 12 ADDRESS TO THE BRITISH ASSOCIATION, 1881, constitutes the digestive membrane, and the outer the skin. To this form Haeckel gave the name Gastreea. — It is, perhaps, doubtful whether the theory of Lankester — and Haeckel can be accepted in precisely the form they propounded it; but it has had an important influence — on the progress of embryology. I cannot quit the — science of embryology without alluding to the very admirable work on ‘ Comparative Embryology’ by our — new general secretary, Mr. Balfour, and also the ‘ Ele- — ments of Embryology’ which he had previously published in conjunction with Dr. M. Foster. 7 - In 1842 Steenstrup published his celebrated work on the ‘Alternation of Generations,’ in which he ~ showed that many species are represented by two — perfectly distinct types or broods, differing in form, structure, and habits; that in one of them males are entirely wanting, and that the reproduction is effected — by fission, or by buds, which, however, are in some — cases structurally indistinguishable from eggs. Steen- . strup’s illustrations were mainly taken from marine or parasitic species, of very great interest, but not gene- — rally familiar, excepting to naturalists. It has since — been shown that the common Cynips or Gallfly is also _ acase in point. It had long been known that in some genera belonging to this group, males are entirely — wanting, and it has now been shown by Bassett, and — more thoroughly by Adler, that some of these species — are double-brooded ; the two broods having been con- — sidered as distinct genera. . 7 Thus an insect known as Neuroterus lenticularis, of which females only occur, produces the familiar oak-spangles so common on the under-sides of oak-— ALTERNATION OF GENERATIONS. : 13 leaves, from which emerge, not Neuroterus lenticularis, _ but an insect hitherto considered as a distinct-species, belonging even to a different genus, Spathegaster bac- carum. In Spathegaster both sexes occur; they pro- duce the currant-like galls found on oaks, and from these galls Neuroterus is again developed. So also the King Charles oak-apples produce a species known as Teras terminalis, which descends to the ground, and makes small galls on the roots of the oak. From these emerge an insect known as Biorhiza aptera, which again gives rise to the common oak-apple. _ Many butterflies, again, are dimorphic, existing under two, or even three, distinct forms—one that of the winter, the other of the summer brood or broods. Weismann has adduced strong reasons for thinking that during the glacial period these species were one- brooded only, and existed in the present winter form; that, as the climate improved, the period of warmth became sufficient to allow the development of a second brood, and led to the gradual rise of the summer form. He and Edwards have shown that, while, by the application of cold, pupe, which would naturally have produced the summer form, can be made to assume the winter dress; it is, on the contrary, far more difficult to change the winter into the summer colouring. In some cases—as for instance in the very curious Leptodora crystallina (a fresh-water crustacean, in- habiting deep lakes and reservoirs, and which, as its name denotes, is almost perfectly transparent )—though - the two forms are almost exactly similar in their mature state, the mode of development is very different; for, while the winter form goes through a well-marked 14. ADDRESS TO THE BRITISH ASSOCIATION, 1881. metamorphosis, in the summer brood the development — is direct. . It might seem that such enquiries as these could — hardly have any practical bearing. Yet it is not im- — probable that they may lead to very important results. For. instance, it would appear that the fluke which ~ produces the rot in sheep, passes one phase of its existence in snails or slugs, and we are not without — hopes that the researches, in which our lamented friend — Prof. Rolleston was engaged at the time of his death, — and which Mr. Thomas is continuing, will lead, if not to — the extirpation, at any rate to the diminution, of a pest E from which our farmers have so grievously suffered. | It was in the year 1839 that Schwann and Schleiden — demonstrated the intimate relation in which animals — and plants stand to each other, by showing the identity of the laws of development of the elementary parts in — the two kingdoms of organic nature. Analogies indeed had been previously pointed out ; the presence of cel- — lular-tissue in certain parts of animals was known, but — Caspar F. Wolff’s brilliant memoir had been nearly for- gotten ; and the tendency of microscopical investigation — had rather been to encourage the belief that no real similarity existed; that the cellular tissue of animals 4 was essentially different from that of plants. This had — arisen chiefly, perhaps, because fully formed tissues were — compared, and it was mainly the study of the growth of — cells which led to the demonstration of the general law of development for all organic elementary tissues. [ As regards descriptive biology, by far the greater — number of species now recorded have been named and — described within the last half-century, and it is not too — INCREASE IN NUMBER OF KNOWN SPECIES. 15 much to say that not a day passes without adding new species to our lists. A comparison, for instance, of the edition of Cuvier’s ‘ Regne Animal,’ published in 1828, as compared with the present state of our knowledge, is most striking. Dr. Giinther has been good enough to make a caleu- lation for me. The numbers, of course, are only ap- proximate, but it appears that while the total number of animals described up to 1831 was not more than 70,000, the number now is at least 320,000. Lastly, to show how large a field still remains for exploration, I may add that Mr. Waterhouse estimates that our Museums contain not fewer than 12,000 species of insects which have not yet been described, while our collections do not probably contain anything like one-half of those actually in existence. Further than this, the anatomy and habits even of those which have been described offer an inexhaustible field for research, and it is not going too far to say that there is not a single species which would not amply repay the devotion of a lifetime. One remarkable feature in the modern progress of biological science has been the application of improved methods of observation and experiment; and the em- ployment in physiological research of the exact mea- surements employed by the experimental physicist. Our microscopes have been greatly improved: achromatic object-glasses were introduced by Lister in 1829; the binocular arrangement by Wenham in 1856; while immersion lenses, first suggested by Amici, and since carried out under the formula of Abbe, are most valuable. The use of chemical re-agents in microscopical investiga- 16. ADDRESS TO THE BRITISH ASSOCIATION, 1881. tions has proved most instructive, and another very — important method of investigation has been the power of obtaining very thin slices by imbedding the object — to be examined in paraffin or some other soft substance. — In this manner we can now obtain, say, fifty separate sections of the egg of a beetle, or the brain of a bee. At the close of the last century, Sprengel published — a most suggestive work on flowers, in which he pointed — out the curious relation existing between these and a insects, and showed that the latter carry the pollen from flower to flower. His observations, however, — attracted little notice until Darwin called attention to — the subject in 1862. It had long been known that the — cowslip and primrose exist under two forms, about — equally numerous, and differing from one another in — the arrangements of their stamens and pistils; the one — form having the stamens on the summit of the flower and the stigma half-way down; while in the other the © relative positions are reversed, the stigma being at the summit of the tube and the stamens half-way down. — This difference had, however, been regarded as a case of mere variability ; but Darwin showed it to be a beauti- — ful provision, the result of which is that insects fertilise each flower with pollen brought from a different plant; and he proved that flowers fertilised with pollen from — the other form yield more seed than if fertilised with pollen of the same form, even if taken from a different plant. Attention having been thus directed to the question, an astonishing variety of most beautiful contrivances have been observed and described by many botanists, especially Hooker, Axel, Delpino, Hildebrand, Bennett, RELATION BETWEEN PLANTS AND INSECTS. 17 Fritz Miiller, and above all Hermann Miiller and Darwin himself. The general result is that to insects, and especially to bees, we owe the beauty of our gardens, the sweetness of our fields. To their beneficent, though unconscious action, flowers owe their scent and colour, their honey—nay, in many cases, even their form. Their present shape and varied arrangements, their brilliant colours, their honey, and their sweet scent are all due to the-selection exercised by insects. In these cases the relation between plants and ts is one of mutual advantage. In many species, owever, plants present us with complex arrangements apted to protect them from insects; such, for in- tance, are in many cases the resinous glands which nder leaves unpalatable ; the thickets of hairs and ther precautions which prevent flowers from being bbed of their honey by ants. Again, more than a ntury ago, our countryman, Ellis, described an merican plant, Dionza, in which the leaves are omewhat concave, with long lateral spines, and a joint the middle, which closes up with a jerk, like a rat- ap, the moment any unwary insect alights on them. e plant, in fact, actually captures and devours in- ts. This observation also remained as an isolated t until within the last few years, when Darwin, ooker, and others have shown that many other pecies have curious and very varied contrivances for upplying themselves with animal food. As regards the progress of botany in other directions, r. Thiselton Dyer has been kind enough to assist me endeavouring to place the principal facts before you. me of the most fascinating branches of botany— c 18 ADDRESS TO THE BRITISH ASSOCIATION, 1881. morphology, histology, and physiology scarcely exis od before 1830. In the two former branches the discoveries of von Mohl are pre-eminent. He first observed cell-division in 1835, and detected the presence of starch — in chlorophyll-corpuscles in 1837, while he first de- scribed protoplasm, now so familiar to us, at least by name, in 1846. In the same year Amici discovered the existence of the embryonic vesicle in the embryo sac, which develops into the embryo when fertilised by the entrance of the pollen-tube into the micropyle. e; existence of sexual reproduction in the lower plants was doubtful, or at least doubted by some eminent authorities : as recently as 1853, when the actual process of fertilisa- tion in the common bladderwrack of our shores w observed by Thuret, while the reproduction of the large: fungi was first worked out by De Bary in 1863. As regards lichens, Schwendener proposed, in 1869, the startling theory, now however accepted by some of the highest authorities, that lichens are not autonomous organisms, but commensal associations of a fungus parasitic on an alga. With reference to the higher Cryptogams, it is hardly too much to say that the whole of our exact knowledge of their life-history has been obtained during the last half-century. Thus in the case of ferns the male organs, or antheridia, were first discovered by Niigeli in 1844, and the archegonia, ‘ : female organs, by Settee in 1848. The early stag in the development of mosses were worked out b y Valentine in 1833. Lastly, the principle of Alternation of Generations in plants was discovered by Hofmeister. This eminent naturalist also, in 1851-4, pointed out the homologies of the reproductive processes in mosses, vascular cryptogams, gymnosperms, and angiosperms. F SYSTEMATIC AND GEOGRAPHICAL BOTANY. 19 _ Geographical Botany can hardly be said to have had y scientific status anterior to the publication of the Origin of Species.’ The way had been paved, how- ver, by A. de Candolle and the well-known essay of ward Forbes—‘ On the Distribution of the Plants d Animals of the British Isles,’—by Sir J. Hooker's troductory essay to the ‘Flora of New Zealand,’ and y Hooker and Thomson’s introductory essay to the Flora Indica.’ One result of these researches has been give the coup-de-grdce to the theory of an Atlantis. astly, in a lecture delivered to the Geographical iety in 1878, Thiselton Dyer himself has summed p the present state of the subject, and contributed an portant addition to our knowledge of plant-distribu- ion by showing how its main features may be ex- lained by migration in latitude from north to south ithout recourse being had to a submerged southern ntinent for explaining the features common to South frica, Australia, and America. The fact that systematic and geographical botany ve claimed a preponderating share of the attention of ritish phytologists, is no doubt in great measure due the ever-expanding area of the British Empire, and e rich botanical treasures which we are continually iving from India and our numerous colonies. The ries of Indian and Colonial Floras, published under e direction of the authorities at Kew, and the ‘ Genera lantarum’ of Bentham and Hooker, are certainly an nour to our country. To similar causes we may e the rise and rapid progress of economic botany, which the late Sir W. Hooker so greatly contri- uted. c 2 -20 ADDRESS TO THE BRITISH ASSOCIATION, 1881. In vegetable physiology some of the most striki researches have been on the effect produced by rays o light of different refrangibility. Daubeny, Draper, ané Sachs have shown that the light of the red end of th spectrum is more effective than that of the blue, so as the decomposition of carbon dioxide (carbonic aci is concerned. 7 Nothing could have appeared less likely than tha researches into the theory of spontaneous generatio should have led to practical improvements in medica science. Yet such has been the case. Only a fei years ago Bacteria seemed mere scientific curiosities It had long been known that an infusion—say, of hay would, if exposed to the atmosphere, be found, a certain time, to teem with living forms. Even thal few who still believe that life would be spontaneousl generated in such an infusion, will admit that thes minute organisms are, if not entirely, yet mainly, d rived from germs floating in our atmosphere; and - precautions are taken to exclude such germs, as in th careful experiments especially of Pasteur, Tynda‘l, a 1 Roberts, everyone will grant that in ninety-nine cast ~ out of a hundred no such development of life will tak place. In 1836-7 Cagniard de la Tour and Schwan independently showed that fermentation was no mel chemical process, but was due to the presence of microscopic plant. But, more than this, it has bee gradually established that putrefaction is also the worl of microscopic organisms. Thirty years, howeve elapsed before these important discoveries received an practical application. At length, however, these facts have led to mos | ' MICROSCOPIC ORGANISMS CAUSES OF DISEASE. 2] important results in Surgery. One reason why com- pound fractures are so dangerous is because, the skin being broken, the air obtains access to the wound, bringing with it innumerable germs, which too often set up putrefying action. Lister first made a practical application of these observations. He set himself to find some substance capable of killing the germs with- out being itself too potent a caustic, and he found that dilute carbolic acid fulfilled these conditions. This discovery has enabled many operations to be per- ormed which would previously have been almost hope- less. The same idea seems destined to prove as useful in Medicine as in Surgery. There is great reason to sup- pose that many diseases, especially those of a zymotic character, have their origin in the germs of special organisms. We know that fevers run a certain definite course. The parasitic organisms are at first few, but adually multiply at the expense of the patient, and then die out again. Indeed, it seems to be thoroughly established that many diseases are due to the excessive multiplication of microscopic organisms, and we are not ithout hope that means will be discovered by which, without injury to the patient, these terrible, though minute, enemies may be destroyed, and the disease thus fayed. Bacillus anthracis, for instance, is now known to be the cause of splenic fever, which is so fatal to seattle, and is also communicable to man. At Bradford, or instance, it is only too well known as the wool- orter’s disease. If, however, matter containing the Bacillus be treated in a particular manner, and cattle be then inoculated with it, they are found to acquire an 22 ADDRESS TO’ THE BRITISH ASSOCIATION, 1881. immunity from the fever. The interesting researches of Burdon-Sanderson, Greenfield, Koch, Pasteur, Tous saint, and others, seem to justify the hope that we may be able to modify these and other germs, and then b h : appropriate inoculation to protect ourselves agains fever and other acute diseases. . Ferrier’s researches in continuation of those of Fritsch and Hitzig have enabled us to localise the function of various parts of the brain, His results have not only proved of great importance in surgel y and in many cases led to successful operations by point: ing out the exact source of the mischief, but an exa knowlediie of the brain is also of the greatest importe a in the treatment of nervous diseases. Echeverria has collected 165 cases of traumatic epilepsy, of which 6 b. per cent. were cured by removing a portion of tk skull, the site for the operation and the exact call of the injury being indicated by cerebral localisation. — The history of Anesthetics is a most remarkabk illustration how long we may be on the very verge 0 a most important discovery. Ether, which, as we all know, produces perfect insensibility to pain, was dis covered as long ago as 1540. The anesthetic property of nitrous oxide, now so extensively used, was observed in 1800 by Sir H. Davy, who actually experimented o1 himself, and had one of his teeth painlessly extractec when under its influence. He even suggests that ‘a nitrous oxide gas seems capable of destroying pain, it could probably be used with advantage in surgical operations.’ Nay, this property of nitrous oxide wai habitually explained and illustrated in the chemical lectures given in hospitals, and yet for fifty years th ' ANZESTHETICS.—ANCIENT CONDITION OF MAN. 23 gas was never used in actual operations. No one did more to promote the use of anesthetics than Sir James Y. Simpson, who introduced chloroform, a substance which was discovered in 1831, and which for a while almost entirely superseded ether and nitrous oxide, though with improved methods of administration, the latter are now coming into favour again. The only other reference to Physiology which time permits me to make, is the great discovery of the reflex action, as it is called, of the nervous centres. Reflex actions had been long ago observed, and it had been shown by Whytt and Hales that they were more or less independent of volition. But the general opinion was that these movements indicated some feeble power of sensation independently of the brain,-and it was not till the year 1832 that the ‘ reflex action ’ of certain nervous centres was made known to us by Marshall Hall, and almost at the same period by Johannes Miiller. Few branches of science have made more rapid pro- gress in the last half-century than that which deals with the ancient condition of Man. When our Association was founded it was generally considered that the human race suddenly appeared on the scene, about 6,000 years ago, after the disappearance of the extinct mammalia, and when Europe, both as regards physical conditions and the other animals by which it was inhabited, was pretty much in the same state as in the period covered by Greek and Roman history. Since then the perse- vering researches of Layard, Rawlinson, Botta and others have made known to us, not only the statues and palaces of the ancient Assyrian monarchs, but even 24 ADDRESS TU THE BRITISH ASSOCIATION, 1881. their libraries ; the cuneiform characters have been de- ciphered, and we can not only see, but read, in the British Museum, the actual contemporary records, on — burnt clay cylinders, of the events recorded in the his- — torical books of the Old Testament and in the pages of © Herodotus. The researches in Egypt also seem to have ~ satisfactorily established the fact that the pyramids — themselves are at least 6,000 years old, while it is ob-— vious that the Assyrian and Egyptian monarchies can- — not suddenly have attained to the wealth and power, the state of social organisation, and progress in the arts, of which we have before us, preserved by the sand — of the desert from the ravages of man, such wonderful” proofs. d In Europe, the writings of the earliest historians _ and poets indicated that, before iron came into general — use, there was a time when bronze was the ordinary — material of weapons, axes, and other cutting imple- — ments, and though it seemed d priori improbable that a — compound of copper and tin should have preceded the — simple metal iron, nevertheless the researches of archa- ologists have shown that there really was in Europe a ‘ Bronze Age,’ which at the dawn of history was june y giving way to that of ‘ Iron.’ : The contents of ancient graves, buried in many cases’ q so that their owner might carry some at least of his — wealth with him to the world of spirits, have proved — very instructive. More especially the results obtained by Nilsson in Scandinavia, by Hoare and Borlase, Bate- — man, Greenwell, and Pitt Rivers, in our own country, — and the contents of the rich cemetery at Hallstadt, left — no room for doubt as to the existence of a Bronze Age; THE BRONZE AND STONE AGES. 25 but we get a completer idea of the condition of Man at this period from the Swiss lake-villages, first made known to us by Keller, and subsequently studied by Morlot, Troyon, Desor, Riitimeyer, Heer, and other Swiss archeologists. Along the shallow edges of the Swiss lakes there -flourished, once upon a time, many populous villages or towns, built on platforms supported by piles, exactly as many Malayan villages are now. Under these circumstances innumerable objects were one by one dropped into the water ; sometimes whole villages were burnt, and their contents submerged ; and thus we have been able to recover, from the waters of oblivion in which they had rested for more than 2,000 years, not only the arms and tools of this ancient people, the bones of their animals, their pottery and ornaments, but the stuffs they wore, the grain they had stored up for future use, even fruits and cakes of bread. . But this bronze-using people were not the earliest occupants of Europe. The contents of ancient tombs give evidence of a time when metal was unknown. This also was confirmed by the evidence then un- expectedly received from the Swiss lakes. By the side of the bronze-age villages were others, not less exten- ‘sive, in which, while implements of stone and bone were discovered literally by thousands, not a trace of metal was met with. The shell-mounds or refuse-heaps accumulated by the ancient fishermen along the shores of Denmark, and carefully examined by Steenstrup, Worsaae, and other Danish naturalists, fully confirmed the existence of a ‘ Stone Age.’ . We have still much to learn, I need hardly say, 26 ADDRESS TO THE BRITISH ASSOCIATION, 1881. about this Stone-age people, but it is surprising how much has been made out. Evans truly observes, in his — admirable work on ‘ Ancient Stone Implements,’ ‘that — so far as external appliances are concerned, they are almost as fully represented as would be those of any — existing savage nation by the researches of a painstak- ing traveller.’ We have their axes, adzes, chisels, borers, scrapers, and various other tools, and we know © how they made and how they used them; we have their personal ornaments and implements of war; we — have their cooking utensils; we know what they ate — and what they wore; lastly, we know their mode of sepulture and funeral customs. They hunted the deer and horse, the bison and urus, the bear and the wolf, — but the reindeer had already retreated to the North. No bones of the reindeer, no fragment of any of the — extinct mammalia have been found in any of the Swiss — lake-villages or,in any of the thousands of tumuli which have been opened in our own country or in Central and — Southern Europe. Yet the contents of caves and of river-gravels afford abundant evidence that there was a — time when the mammoth and rhinoceros, the musk-ox. and reindeer, the cave lion and hyena, the great bear and the gigantic Irish elk wandered in our woods and valleys, and the hippopotamus floated in our rivers ; when England and France were united, and the Thames and the Rhine had a common estuary. This was long supposed to be before the advent of man. At length, however, the discoveries of Boucher de Perthes in the valley of the Somme, supported as they are by the researches of many continental naturalists, and in our own country of MacEnery and Godwin Austen, Prest-— THE PALZOLITHIC AND NEOLITHIC AGES, 27 wich and Lyell, Vivian and Pengelly, Christy, Evans, and many moré, have proved that man formed a humble part of this strange assembly. Nay, even at this early period there were at least two distinct races of men in Europe ; one of them—as _ Boyd-Dawkins has pointed out—closely resembling the modern Esquimaux in form, in his weapons and implements, probably in his clothing, as well as in so many of the animals with which he was associated. At this stage Man appears to have been ignorant of pottery, to have had no knowledge of agriculture, no domestic animals, except perhaps the dog. His weapons were the axe, the spear, and the javelin; I do not believe he knew the use of the bow, though he was probably acquainted with the lance. He was, of course, ignorant of metal, and his stone implements, though skilfully formed, were of quite different shapes from those of the second Stone age, and were never ground. This earlier Stone period, when man co- existed with these extinct mammalia, is known as the Paleolithic, or Early Stone Age, in opposition to the Neolithic, or Newer Stone Age. The remains of the mammalia which co-existed with man in pre-historic times have been most care- fully studied by Owen, Lartet, Riitimeyer, Falconer, Busk, Boyd-Dawkins, and others. The presence of the mammoth, the reindeer, and especially of the musk-ox, indicates a severe, not to’ say an arctic, climate—the existence of which, moreover, was proved by other considerations ; while, on the contrary, the hippo- potamus requires considerable warmth. How, then, is _ this association to be explained ? affected by geographical conditions, the cold of the— 4 glacial period was, I believe, mainly due to the eccen- — tricity of the earth’s orbit combined with the oblique — effects of precession of the ecliptic. The result of the — latter condition is a period of 21,000 years, during one half of which the northern hemisphere is warmer than — the southern, while during the other 10,500 years the — reverse is the case. At present we are in the former % phase, and there is, we know, a vast accumulation of — ice at the south pole. But when the earth’s orbit is nearly circular, as it is at present, the difference between _ the two hemispheres is not very great ; while on the — contrary, as the eccentricity of the orbit increases, the contrast between them increases also. This eccentricity — is continually oscillating within certain limits which — Croll and subsequently Stone have calculated for the last million years. At present the eccentricity is °016 and the mean temperature of the coldest month in London — is about 40°. Such has been the state of things for nearly 100,000 years; but before that there was a a period, beginning 300,000 years ago, when the eccen- — tricity of the orbit varied from ‘26 to ‘57. The result of this would be greatly to increase the effect due to the q ‘obliquity of the orbit ; at certain periods the climate — would be much warmer than at present, while at others — the number of days in winter would be twenty more, — and of summer twenty less, than now, while the mean temperature of the coldest month would be lowered — 20°. We thus get something like a date for the last — glacial epoch, and we see that it was not simply a — period of cold, but rather one of extremes, each beat of CONDITION OF MAN IN PRE-HISTORIC TIMES. 29 the pendulum of temperature lasting for no less than 21,000 years. This explains the fact that, as Morlot showed in 1854, the glacial deposits of Switzerland, and, as -we now know, those of Scotland, are not a single uniform layer, but a succession of strata indi- eating very different conditions. I agree also with Croll and Geikie in thinking that these considerations explain the apparent anomaly of the co-existence in the same gravels of arctic and tropical animals; the former having lived in the cold, while the latter Motta 5 in thé hot, periods. It is, 1 think, now well established that man in- habited Europe during the milder periods of the glacial epoch. Some high authorities indeed consider that we have evidence of his presence in pre-glacial and even in Miocene times, but I confess that I am not satisfied on this point. Even the more recent period carries back the record of man’s existence to a distance so great as altogether to change our views of ancient history. Nor is it only as regards the antiquity and material condition of man in pre-historic times that great pro- gress has been made. If time permitted I should have been glad to have dwelt on the origin and development of language, of custom, and of law. On all of these the comparison of the various lower races still inhabiting so large a portion of the earth’s surface, has thrown much light; while even in the most cultivated nations we find survivals, curious fancies, and lingering ideas ; the fossil remains as it were of former customs and religions, embedded in our modern civilisation, like the relics of extinct animals in the crust of the earth. NM 30 ADDRESS TO THE BRITISH ASSOCIATION, 1881. In geology the formation of our Association coin- q cided with the appearance of Lyell’s ‘ Principles of — Geology,’ the first volume of which was published in a 1830 and the second in 1832. At that time the re- 4 ceived opinion was that the phenomena of Geology could _ only be explained by violent periodical convulsions, and a high intensity of terrestrial energy culminating in repeated catastrophes. Hutton and Playfair had _ indeed maintained that such causes as those now in operation, would, if only time enough were allowed, account for the geological structure of the earth; never- _ theless the opposite view generally prevailed, until Lyell, with rare sagacity and great eloquence, with a — _ wealth of illustration and most powerful reasoning, convinced geologists that the forces now in action are powerful enough, if only time be given, to produce results quite as stupendous as those which Science records. | As regards statigraphical geology, at the time of — the first meeting of the British Association at York, the strata between the carboniferous limestone and the chalk had been mainly reduced to order and classified, chiefly through the labours of William Smith. But — the classification of all the strata lying above the chalk and below the carboniferous limestone respectively, — remained in a state of the greatest confusion. The year 1831 marks the period of the commencement of the joint labours of Sedgwick and Murchison, which resulted in the establishment of the Cambrian, Silurian, and Devonian systems. Our Pre-Cambrian strata have — recently been divided by Hicks into four great groups — of immense thickness, and implying a great lapse of — GEOLOGICAL RESEARCHES. 31 time; but no fossils have yet been discovered in them. Lyell’s classification of the Tertiary deposits; the result of the studies which he carried on with the assistance of Deshayes and others, was published in the third volume of the ‘Principles of Geology’ in 1833. The establishment of Lyell’s divisions of Eocene, Miocene, and Pliocene, was the starting-point of a most important series of investigations by Prestwich and others of these younger deposits ; as well as of the post- tertiary, quaternary, or drift beds, which are of special interest from the light they have thrown on the early history of man. A full and admirable account of what has recently been accomplished in this department of science, es- pecially as regards the palzozoie rocks, will be found in Etheridge’s late address to the Geological Society. The thickness of the sedimentary strata implies an enormous lapse of time, but the amount of subsequent destruction which has taken place is scarcely less sur- prising. Ramsay, for instance, has shown that in Wales from 9,000 to 11,000 feet of solid rock have been re- moved from large tracts of country. Faults or cracks there extend for miles, with the strata on one side raised in some cases as much as 10,000 feet above the same strata on the other, and yet there is not on the surface the slightest vestige of this gigantic dislocation. The long lines of escarpment again, which stretch for miles across our country, and were long supposed _to be ancient coast lines, are now ascertained, mainly through the researches of Whitaker, to be due to the differential action of aerial causes. Before 1831 the only geological maps of this 82. ADDRESS TO THE BRITISH ASSOCIATION, 1881. country were William Smith’s general and county map: . published between the years 1815 and 1824. In th 2 year 1832 De la Beche made proposals to the Board of Ordnance to colour the ordnance-maps geologically, and a sum of 300/. was granted for the purpose. Out a this small beginning grew the important work of the Geological Survey. a The cause of slaty cleavage had long been one o £ the great difficulties of geology. Sedgwick suggeste d that it was produced by the action of crystalline o r polar forces. According to this view miles and miles — of country, comprising great mountain masses, were ~~ neither more nor less than parts of a gigantic crystal. Sharpe, however, called attention to the fact that shells and other fossils contained in slate rocks are compressed in a direction at right angles to the planes of cleavage, — as if the rocks had been seized in the jaws of a gigantic vice. Sorby first maintained that the cleavage itself was due to pressure. He observed slate rocks contain- ing small plates of mica, and that the effect of pressure would tend to arrange these plates with their flat sur- faces perpendicu'ar to the direction of the pressure. Tyndall has since shown that the presence of flat flakes is not necessary. He proved by experiment that pure wax could be made by pressure to split into plates of great tenuity, which he attributes mainly to the laters li sliding of the particles of the wax over each other ; and thus the result of pressure on such a mass is to develop” a fissile structure similar to that produced in wax on a_ small scale, or on a great one in the slate rocks of Cum- berland or Wales. The difficult problem of the conditions under which THE PHYSICAL STRUCTURE OF THE EARTH. 353 granite and certain other rocks were formed was attacked by Sorby with great skill in a paper read before the Geological Society in 1858. The microscopic spaces in many minerals contain a liquid which does not entirely fill the hollow, but leaves a small vacuum ; and Sorby ingeniously pointed out that the rock must have solidi- fied at least at a temperature high enough to expand the liquid so as to fill the cavity. Sorby’s important memoir laid the foundation of microscopic petrography, which is now not only one of the most promising ‘branches of geological research, but which has been successfully applied by Sorby himself, and by Maske- lyne, to the study of meteorites. As regards the physical character of the earth, two theories have been held: one, that of a fluid interior covered by a thin crust ; the other, of a practically solid sphere. The former is now generally considered by physicists to be untenable. Though there is still much - difference of opinion, the prevailing feeling on the sub- ject has been expressed by Professor Le Conte, who says, ‘the whole theory of igneous agencies—which is little less than the whole foundation of theoretic geology —must be reconstructed on the basis of a solid earth.’ In 1837 Agassiz startled the scientific world by his *Discours sur l’ancienne extension des Glaciers,’ in which, developing the observation already made by Charpentier and Venetz, that boulders had been trans- ported to great distances, and that rocks far away from, or high above, existing glaciers, are polished and scratched by the action of ice, he boldly asserted the existence of a ‘glacial period,’ during which Switzer- D - now under review. For instance, the gigantic Ce: 10 New Zealand by the same distinguished naturalist | 1 34. ADDRESS TO THE BRITISH ASSOCIATION, 1881. a land and the North of Europe were sere to” ore : cold and buried under a vast sheet of ice. 3 The ancient poets described certain gifted mo eal as privileged to descend into the interior of the ¢ and have exercised their imagination in resin wonders there revealed. As in other cases, how the realities of science have proved more varied antl um prising than the dreams of fiction. Of the gigantic an extraordinary animals thus revealed to us, by far th greatest number have been described during the — saurus was described by Owen in 1338, the Dinornis ¢ 1839, the Mylodon in the same year, and the Arch teryx in 1862. In America, a large number of remarkable for m have been discovered, mainly by Marsh, Leidy, and Cop pe. Marsh has made known to us the Titanosaurus, of th American (Colorado) Jurassic beds, which is, perhe ap’ the largest land animal yet known, being a hundre feet in length, and at least thirty in height, though i seems possible that even these vast dimensions were ex ceeded by those of the Atlantosaurus. Nor mus: i omit the Hesperornis, described by Marsh in 1872, as carnivorous, swimming ostrich, provided with teeth which he regards as a character inherited from reptilia ancestors ; the Ichthyornis, stranger still, with bona . vertebree, like those of fishes, and teeth set in socke while in the Eocene deposits of the Rocky Mountil the same indefatigable paleontologist, among other ver interesting remains, has discovered three new oroups ¢ remarkable mammals, the Dinocerata, Tillodontia, ant a “- PALEONTOLOGY, BO Brontotheride. He has also described a number of “small, but very interesting Jurassic mammalia, closely related to those found in our Stonesfield Slate and Purbeck beds, for which he has proposed a new order, _*Prototheria.’ - Lastly, I may mention the curiously anomalous Reptilia from South Africa, which have been made known to us by Professor Owen. Another important result of recent paleontological research is the law of brain-growth. It is not only in the higher mammalia that we find forms with brains much larger than any existing, say, in Miocene times. The rule is almost general that—as Marsh has briefly ‘stated it—‘all tertiary mammals had small brains.’ We may even carry the generalisation further. The cretaceous birds had brains one-third smaller than those of our own day, and the brain-cavities of the Dinosauria of the Jurassic period are much smaller than in any existing reptiles. As giving, in a few words, an idea of the rapid pro- gress in this department, I may mention that Morris’s ‘Catalogue of British Fossils,’ published in 1843, con- tained 5,300 species ; while that now in preparation by . ‘Mr. Etheridge enumerates 15,000. But if these figures show how rapid our recent pro- gress has been, they also very forcibly illustrate the imperfection of the geological record, giving us, I will not say a measure, but an idea, of the imperfection of the geological record. The number of all the described recent species is over 300,000, but certainly not half are yet on our lists, and we may safely take the total number of recent species as being not less than 700,000. But in former times there have been at the very least p2 36 ADDRESS TO THE BRITISH ASSOCIATION, 1881. — a twelve periods, in each of which by far the gre number of species were distinct. True, the number ¢ | species was probably not so large in the earlier perioc ds as at present ; but if we make a liberal allowance for this, we shall have a total of more than 2 ,000, 00 F species, of which about 25,000 only are as yet n record ; and many of these are only represented by few, some only by a single specimen, or even only by: fragment. “4 The progress of paledoatalae may also be marked | by the extent to which the existence of groups has been, if I may so say, carried back in time. Thus I be ee that in 1830 the earliest known quadrupeds were sm marsupials belonging to the Stonesfield Slate ; most ancient mammal now known is vical antiquus from the Keuper of Wiirtemberg: the oles : bird known in 1831 belonged to the period ora London Clay, the oldest now known is the Archeop teryx of the Solenhofen Slate, though it is probal ble that some at any rate of the footsteps on the Triassic rocks are those of birds. So again the Amphibia have been carried back from the Trias to the Coal-measures ; Fish from the Old Red Sandstone to the Upper Silurian i Reptiles to the Trias ; Insects from the Cretaceous t the Devonian; Mollusca and Crustacea from the Silurian to the pa Cambrian. The rocks below the Cambrian, though of immense thickness, have afforded no relics of animal life, if we except the problematical Eozoon Canadense, so ably studied by Dawson and Carpenter. But if paleontology as yet throws no light on the original forms of life, we must remember th ut the simplest and the lowest organisms are so soft and ee GEOGRAPHY. 37 perishable that they would leave ‘not a wrack behind.’ I will not, however, enlarge on this branch of science, because we shall have the advantage on Friday of hearing it treated with the skill of a master. _ Passing to the Science of Geography, Mr. Clements Markham has recently published an excellent summary _of what has been accomplished during the half-century. As regards the Arctic regions, in the year 1830 the coast line of Arctic America was only very partially known, the region between Barrow Strait and the con- _tinent, for instance, being quite unexplored, while the eastern sides of Greenland and Spitzbergen, and the coasts of Nova Zembla, were almost unknown. Now the whole coast of Arctic America has been delineated, the remarkable archipelago to the north has been ex- plored, and no less than seven north-west passages—_ none of them, however, unfortunately of any practical value—have been traced. The north-eastern passage, on the other hand, so far at least as the mouths of the great Siberian rivers, may perhaps hereafter prove of ‘commercial importance. In the Antarctic regions, Enderby and Graham Lands were discovered in 1831-2, Balleny Islands and Sabrina Land in 1839, while the fact of the existence of the great southern continent was established in 1841 by Sir James Ross, who penetrated in 1842 to 78° 11’, the southernmost point ever reached. In Asia, to quote from Mr. Markham, ‘ our officers _ have mapped the whole of Persia and Afghanistan, sur- veyed Mesopotamia, and explored the Pamir steppe. Japan, Borneo, Siam, the Malay peninsula, and the greater part of China have been brought more com- 38 ADDRESS TO THE BRITISH ASSOCIATION, 1861. =. pletely to our knowledge. Eastern Turkestan has t been visited, and trained native explorers have ee the remotest fountains of the Oxus, and the wild plateaux of Tibet. Over the northern half of the — Asiatic Continent the Russians have displayed great activity. They have traversed the wild steppes and deserts of what on old atlases was called Independent Tartary, have surveyed the courses of the Jaxartes, a 4 Oxus, and the Amur, and have navigated the Caspian and the Sea of Aral. They have pushed their scientifi ic investigations into the Pamir and Eastern Turkestan, until at last the British and Russian surveys have be = connected.’ E Again, fifty years ago the vast central regions ¢ 0 of Africa were almost a blank upon our best maps. he rudely drawn lakes and rivers in maps of a more ancier : date had become discredited. These maps did not among themselves, the evidence upon which iggy laid down could not be found, they were in m a respects highly improbable, and they seemed incon- sistent with what had then been ascertained concerning the Niger and the Blue and White Niles. At the a of which I speak, the Sahara had been crossed by English travellers from the shores of the Mediterranean ; but the southern desert still formed a bar to cavellll from the Cape, while the accounts of traders and others who alone had entered the country from the eastern ¢ nd western coasts were considered to form an insufficient 7 basis for a map. 4 Since that time the successful crossing of the Kalahari desert to Lake Ngami has been the prelude to an era of African discovery. Livingstone explored HYDROGRAPHY. _ 39 the basin of the Zambesi, and discovered vast lakes and _ waters which have proved to be those of the higher Congo. Burton and Speke opened the way from the West Coast, which Speke and Grant pursued into and down the Nile, and Stanley down the course of the middle and lower Congo; while the vast extension of Egyptian dominion has brought a huge slice of equa- torial Africa within the limits of semi-civilisation. The western side of Africa has been attacked at many points. Alexander and Galton were among the first to make _ known to us its western tropical regions immediately _ to the north of the Cape Colony; the Ogowé has been _ explored; the Congo promises to become a centre of trade, and the navigable portions of the Niger, the Gambia, and the Senegal are familiarly known. The progress of discovery in Australia has been as remarkable as that in Africa. The interior of this great continent was absolutely unknown to us fifty _ years ago, but is now crossed through its centre by the electric telegraph, and no inconsiderable portion of it is _ turned into sheep-farms. It is an interesting fact that General Sabine, so long one of our most active officers, and who is still with us, though, unfortunately his health has for some time prevented him from attending our meetings, was born on the very day that the first settler landed in Australia. In hydrography our charts have been immensely improved. ‘he study of rivers and of the physical geography of the sea may indeed almost be said to have come into existence as a science during the last fifty years, and in the words of Jansen, it was Maury ‘ who, by his wind and current charts, his trade-wind, storm, 40 ADDRESS TO THE BRITISH ASSOCIATION, 1881. 4 and rain charts, and last, but not least, by his work ¢ on the physical geography of the sea, gave the first grea impulse to all subsequent researches.’