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'tKEE'l I W*?4X- .^'.'; ISMt -jM m^. . ^KC'l^.Vat.'it :AiU' .** SOME SALIENT POINTS IN THE SCIENCE OF THE EARTH on ••• BY -„^ SIR J. WILLIAM DAWSO C.M.G., LL.D., F.R.S., F.G.S., ETC. N IVITH FORTV-SIX ILLUSTRATIONS Montreal W. DRYSDALE AND CO. 232, ST. JAMES STREET MDCCCXCIU WORKS BY THE SAME AUTHOR. Modern Science in Bible Lands. With Illus- trations. Popular Edition, Re.'ised. Crown 8vo, 6/- The Origin of the World, according to Revela- tion and Science. Sixth Edition. Crown 8vo, cloth, 7/6. The Story of the Earth and Man. Tenth Edition, with Twenty Illustrations. Crown 8vo, cloth, 7/6. Fossil Men and Their Modern Representa- tives. An attempt to illustrate the Characters and Con- dition of Pre-historic Men in Europe, by those of the American Races. With numerous Illustrations. Third Edition. Crown Svo, cloth, 7/6. LONDON : HODDER AND STOUGHTON. ^xidksuj^*imu- PREFACE. •^ I ^HE present work contains much that is new, and much in correction and amplification of that which is old ; and is intended as a closing deliverance on some of the more important questions of geology, on the part of a veteran worker, conversant in his younger days with those giants of the last generation, who, in the heroic age of geological science, piled up the mountains on which it is now the privilege of their successors to stand. J. W. D. Montreal, 1893. s. v. i i CONTENTS. The Starting-Point CHAPTER I. • • PAGE World-Making . CHAPTER n. CHAPTER nr. The Imperfection of the Geological Record . 39 CHAPTER IV. 1 HE History of the North Atlantic 57 The Dawn of Life . CHAPTER V. 95 „, CHAPTER VI. What may be Learned from Eozoon • • 135 CHAPTER VII iiiE Apparition and Succ ''.ssioN of Animal Forms 169 ^ ,, CHAPTER VIII. IHE Genesis and Migrations of Plants . 20I CHAPTER IX. ihe Growth of Coal vu 233 Vlll CONTENTS. CHAPTER X. lAciK The Oldest Air-breathers 257 CHAPTER XI. Markings, Footprints, and Fucoids 311 C AFTER Xn. Pre-determination in Nat jre 329 CEIAPTER XHI. The Great Ice A(;e 345 CHAPTER XIV. Causes of Climatal Change 383 f CHAl'TER XV. The Distribution of Animals and Plants as Related jo Geographical and Geological Changes . . . 401 CHAPTER XVI. Alpine and Arctic Plants in Connection with Geological History 425 CHAPTER XVII. Early Man 459 CHAPTER XVIII. Man in Nature 481 LIST OF ILLUSTRATIONS. Cape Trinity on the Saguenay Folding : the Earth's Crust . Cambro-Silurian Sponges Map of the North Atlantic Nature-print of Eozoon . Laurentian Hills, Lower St. Lawrence Section from Petite Nation Seignior^ TJie Laurentian Nucleus of the American Continent Attitude of Limestone at St. Pierre ^Veathered Eozoon and Canals •y to St. Jerome 7 J Group of Canals in Eozoon Amoeba and Actinophrys Minute Foraminiferal Forms Section of a Nummulite Portion of Shell of Calcarina Weathered Eozoon with Oscular tubes Diagram showing different States of Fossilization Tubulate Coral . * " • • , Slice of Crystalline Lower Silurian Limestone Walls of Eozoon penetrated with Canals Joint of a Crinoid ..... Shell from a Silurian Limestone, Wales Casts of Canals of Eozoon in Serpentine Canals of Eozoon . * • • Primordial Trilobites . . Primitive Fishes . Devonian Forest .... Coal Section in Nova Scotia . of To face J'AGE Frontispiece To face 9 39 57 95 100 101 103 109 112 113 115 119 123 127 128 Toface 135 Cell of a 139 141 141 14s 146 »47 147 169 185 i> 201 «» 233 Toface ILLUSTRATIONS. Skeleton of Hylonomus Lyelli Footprints of Hyloptts Logani Humerus and Jaws of Dendrerpeton Reptiliferous Tree .... Microsaurian, restored . DolicJiosoma longissimiim, restored . Pupa and Conulas .... Millipedes and Insect . Footprints cf Limulus . . ' , Rnskhuites Gnnvillensis Restorat'on of Protospongia teiranenia ' Giant Net- sponge .... Boulder Beach, Little Metis . Palaeography of North America Distribi.'.ion of Animals in Time . TucIn .man's Ravine and Mount Washin Pre-historic Skulls . . . Primitive Sculpture . * . on To face PAGE i » 261 » » 273 '» 277 t> 279 287 1 > 289 295 311 323 329 ZZ7 345 383 401 425 459 481 ■■ TABLE OF GEOLOGICAL HISTORY. NoN-GEOLOG.c. readers will find in the following table a condensed explanation of the more important technical terms used m the following pages. The order is from older to newer. GREATER PERIODS. SYSTEMS OF FORMATIONS. Arch^an or j Pre-Laurentian Eozoic Lauientian characteristic fossils. Paleozoic Mesozoic Kainozoic or Tertiary Huronian Cambrian Cambro-Silurian" Silurian f Devonian Carboniferous Permian Prot ozoa Protophyta Triassic Jurassic Cretaceous Eocene Miocene Pliocene Pleistocene Modern / Crustaceans Molluscs Worms Corals, fc. Fishes Amphibians Algce Cryptoganious and Ciymnospermous Plants. Pines and 'Reptiles f'I- ... Cycads .tarhest Mammals. Trees of mod types. ern Higher Mammals of extinct forms Recent Mammals and Mar.. Modern Plants. Ordovician of Lapworth + c„i • ipwortn. f Salopian of Lapworth. ERRATA IN • LIST AND LEGENDS OF ILLUSTRATIONS, ETC. Owing to an illness ./hile the work was in press, the author was unable to revise proofs of the Legends of the Illustrations ; hence the following errata. List of Illustrations. Page ix, for "Tabulate " read '• T u TS ?: a, Ui C r. CJ •/5 rt r- ' wi ^ c (J o ^ n V ^'— ' 1 rt rt o •^ u rt 1^ O ai < D 4-t w ■^ rj a ■r; WoKLUMAKIN'li 19 same manner with those below them ; but we find these now assoeiatecl with great l)ecl.s of h'mestone and dolomite, which must have been formed by the separation of cnlcium and mag- nesium carbonates from the sea water, either by chemical pre- cipitation or by the agency of living beings. \Vc have also quartzite, (juartzose gneisses, and even pebble i)eds, which in- form us of sandbanks and shores. Nay, more, we have beds coii.aining graphite which must be the residue of plants, and iron ores which tell of the deoxidation of iron oxide by organic matters. In short, here we have evidence of new factors in world-building, of land and ocean, of atmospheric decay of rocks, of deoxidizing processes carried on by vegetable life on the land and in the waters, c*" limestone-building in the sea. To afford material for such rocks, the old Ottawa gneiss must have been lifted up into continents and mountain masses by bendings and foldings of the original crust. Under the slow but sure action of the carbon dioxide dissolved in rainwater, its felspar had crumbled down in the course of ages. Its potash, soda, lime, magnesia, and part of its silica had been washed into the sea, there to enter into new combinations and to form new deposits. The crumbling residue of fine clay and sand had been also washed down into the borders of the ocean, and had been there deposited in beds. Thus the earth had entered into a new phase, which continues onward through the geological ages ; and I place in the reader's hands one key for unlocking the mystery of the world in affirming that this great change took place, this new era w-as inaugurated in the midst of the Laurentian period, the oldest of our great divisions of the earth's geological history.* ' I follow the original arrang-f;mcnt o( Logan, \vlio first clefined this succcision in the extensive and excellent exposures of these rocks in Canada. l'ds;.'\vhere the subject has ufleii been confused and mixed with local de- tails. The same facts, thoagh sometimes under different names, are re- corded by the geologists of Scandinavia, Britain, and the United States, 20 WOKLD-MAKING Was not this a fit period for the first appearance of Ufe? should we not expect it to appear, independently of the evidence of the fact, so soon at least as the temperature of the ocean falls sufficiently low to permit its existence ? ^ I do not propose to enter here into that evidence. This we shall have occasion to consider in the sequel. I would merely say here that we should bear in mind that in this latter half of the Lower Laurentian, or if we so choose to style it, Middle Laurentian period, we have the conditions required for life in the sea and on the land ; and since in other periods we know that life was always present when its conditions were present, it is not unreasonable to look for the earliest traces of life in this forma- tion, in which we find, for the first time, the completion ot those physical arrangements which make life, in such forms of it as exist in the sea, possible. This is also a proper place to say something of the disputed doctrine of what is termed metamorphism, or the chemical and molecular changes which old rocks have undergone. The Laurentian rocks are undoubtedly greatly changed from their original state, more especially in the matters of crystalli- zation and the formation of disseminated minerals, by the action of heat and heated water. Sandstones have thus passed into quartzites, clays into slates and schists, limestones into mar- bles. So far, metamorphism is not a doubtful question ; but when theories of metamorphism go so far as to suppose an actual change of one element for another, they go beyond the bounds of chemical credibility; yet such theories of meta- morphism are often boldly advanced and made the basis of important conclusions. Dr. Hunt has happily given the name " metasomatosis " to this imaginary and improbable kind of ami the acceptance of the conclusions of Nicol and Lapworth has served to bring even the rocks of the Highlands of Scotland more into line with those of Canada, * Dana states this at 180'' F. for plants and 120° for animals. WOKLD-MAKINC 21 metamorphism. I would have it to be understood . in speaking of the metamorphism of the older crystalline rocks, it is not to this meiusomatosis that I refer, and that I hold that rocks which have been produced out of the materials decom- posed by atmospheric erosion can never by any process of metamorphism be restored to the precise condition of the Laurentian rocks. Thus, there is in the older formatioiis a genealogy of rocks, which, in the absence of fossils, may be used with some confidence, but which does not apply to the more modern deposits, and which gives a validity to the use of mineral character in classifying older rocks which does not hold for later formations. Still, nothing in geology abso- lutely perishes, or is altogether discontinued ; and it is prob- able that, down to the present day, the causes which produced the old Laurentian gneiss may still operate in limited locali- ties. Then, however, they were general, not exceptional. \t is further to be observed that the term gneiss is sometimes of wide and even loose application. Beside the typical orthoclase and hornblendic gneiss of the Laurentian, there are micaceous, quartzose, garnetiferous and many other kinds of gneiss ; and even gneissose rocks, which hold labradorite or anorthite in- stead of orthoclase, are sometimes, though not accurately, in- cluded in the term. The Grenville series, or Middle Laurentian, is succeeded by what Logan in Canada called the Upper Laurentian, and which other geologists have called the Norite or Norian series. Here we still have our old friends the gneisses, but somewhat peculiar in type, and associated with them are great beds and masses, rich in lime-felspar, the so-called labradorite and anorthite rocks. The precise origin of these is uncertain, but this much seems clear, namely, that they originated in circumstances in which the great limestones deposited in the Lower or Middle Lauren- tian were beginning to be employed in the manufacture, prob- ably by aqueo-igneous agencies, of lime-felspars. This proves •fr^^^a^mmt 22 WORLD-MAKING ri the Norian rocks to be younger than the Lower Laurentian, and that, as Logan supposed, considerable earth movements had occurred between the two, implying lapse of time, while it is also evident that the folding and crumpling of the Lower Lau- rentian had led to great outbursts of igneous matter from below the crust, or from its under part. Next to the Laurentian, but probably after an interval, the rocks of which are yet scarcely known, we have the Huronian of Logan, a series much less crystalline and more fragmentary, and affording more evidence of land elevation and atmo- spheric and aqueous erosion than those preceding it. It has extensive beds of volcanic rock, great conglomerates, some of them made up of rounded fragments of Laurentian rocks, and others of quartz pebbles, which must have been the remains of rocks subjected to very perfect decay. The pure quartz-rocks tell the same tale, while slates and limestones speak also of chemical separation of the materials of older rocks. The Hu- ronian evidently tells of previous movements in the Lauren- tian, and changes which allowed the Huronian to be deposited along its shores and on the edges of its beds. Yet the Huronian itself is older than the Palceozoic scries, and affected by power- ful earth movements at an earlier date. Life existed in the waters in Huronian times. We have spicules of sponges in the limestone, and organic markings on the slaty beds ; but diey are few, and their nature is uncertain. Succeeding the Huronian, and made up of its d3ns and that of the Laurentian, we have the great Cambrian series, that in which we first find undoubted evidence of abundant marine life, and which thus forms the first chapter in thi great Paloeozoic book of the early history of the world. Here let it be observed we have at least two wide gaps in our history, marked by the crumpling up, first, of the Laurentian, and then of the Huronian beds. After what has been said, the reader will perhaps not be r WORLD-MA KINC; 23 lid -s, Int lat it in 1)0 astonished that fierce geological battles have raged over the old crystalline rocks. By some geologists they are almost entirely explained away, or referred to igneous action, or to the alteration of ordinary sediments. Under the treatment of another school they grow to great series of Pre-Cambrian rocks, constituting vast systems of formations, distinguishable from each other chiefly by differences of mineral character. Facts and fossils are daily being discovered, by which these disputes will ultimately be settled. After the solitary appearance of Eozoon in the Lauren tian, and of a few uncertain forms in the Huronian, we find our- selves, in the Cambrian, in the presence of a nearly complete invertebrate fauna of protozoa, polyps, echinoderms, mollusks and Crustacea, and this not confined to one locality merely, but apparently extended simultaneously throughout the ocean, over the whole world. This sudden incoming of animal life, along with the subsequent introduction of successive groups of invertebrates, and finally of vertebrate animals, furnishes one of the greatest unsolved problems of geology, which geologists were wont to settle by the supposition of successive creations. In the sequel I shall endeavour to set forth the facts as to this succession, and the general principles involved in it, and to show the insufficiency of certain theories of evolution suggested by biologists to give any substantial aid to the geologist in these questions. At present I propose merely to notice some of the general principles which should guide us in studying the development of life in geological time, and the causes which have baffled so many attempts to throw light on this obscure portion of our unsolved problems. It has been urged on the side ot rational evolution-- and there are both rational and irrational forms of this many-sided doctrine — that this hypothesis does not profess to give an explanation of the absolute origin of life on our planet, or even of the original organization of a single cell, or of a simple mass I i Sep 24 WORLD-MAKING It 1 of protoplasm, living or dead. All experimental attempts to produce by synthesis the complex albuminous substances, or to obtain the living from the non-living, have so far been fruitless, and indeed we cannot imagine any process by which such changes could be effected. That they have been effected we know, but the process employed by their maker is still as mysterious to us as it probably was to him who wrote the words : — " And God said, Let the waters swarm with swarmers." How vast is the gap in our knowledge and our practical power implied in this admission, which must, however, be made by every mind not absolutely blinded by a superstitious belief in those forms of words which too often pass current as philosophy. But if we are content to oiait with a number of organisms ready made — a somewhat humiliating start, however — we still have to ask— How do these vary so as to give new species ? It is a singular illusion, and especially in the case of men who profess to be believers in natural law, that variation may be boundless, aimless and fortuitous, and that it is by spontaneous selection from varieties thus produced that development arises. But surely the supposition of mere chance and m.agic is un- worthy of science. Varieties must have causes, and their causes and their effects must be regulated by some law or laws. Now it is easy to see that they cannot be caused by a mere innate tendency in the organism itself. Every organism is so nicely equilibrated that it has no such spontaneous tendency, except within the limits set by its growth and the law of its periodical changes. There may, however, be equilibrium more or less stable. I believe all attempts hitherto made have failed to account for the fixity of certain, nay, of very many, types throughout geological time, but the mere consideration that one may be in a more stable state of equilibrium than another, so far explains it. A rocking stone has no more spontaneous tendency to move than an ordinary boulder, but WORLD-MAKING 25 it may be made to move with a touch. So it probably is with organisms. But if so, then the causes of variation are external, as in many cases we actually know them to be, and they must depend on instability with change in surroundings, and this so arranged as not to be too extreme in amount, and to operate in some determinate direction. Observe how remarkable the unity of the adjustments involved in such a supposition ! — how superior they must be to our rude and always more or less unsuccessful attempts to produce and carry forward varieties and races in definite directions ! This cannot be chance. If it exists, it must depend on plans deeply laid in the nature of things, else it would be most monstrous magic and causeless miracle. Still more certain is this conclusion when we con- sider the vast and orderly succession made known to us by geology, and which must have been regulated by fixed laws, only a few of which are as yet known to us. Beyond these general considerations we have others of a more special character, based on palaeontological facts, which show how imperfect are our attempts as yet to reach the true causes of the introduction of genera and species. One is the remarkable fixity of the leading types of living beings in geological time. If, instead of framing, like Haeckel, fanciful phylogenies, we take the trouble, with Barrande and (iaudry, to trace the forms of life through the period of their existence, each along its own line, we shall be greatly struck with this, and especially with the continuous existence of many low types of life through vicissitudes of physical conditions of the most stupendous character, and over a lapse of time scarcely conceivable. "What is still more remarkable is that this holds in groups which, within certain limits, are perhaps the most variable of all. In the present world no creatures are individually more variable than the i)rotozoa ; as, for example, the foraminifera and the sponges. Vet these groups are fundamentally the same, from the beginning of the Paloeo- r7?= ^ssmm 26 WORLD-MAKING zoic until now, and modern species seem scarcely at all to differ from specimens procured from rocks at least half-way back to the beginning of our geological record. If we suppose that the present sponges and foraminifera are the descendants of those of the Silurian period, we can affirm that in all that vast lapse of time they have, on the whole, made little greater change than that which may be observed in variable forms at present. The same remark applies to other low animal forms. In types somewhat higher and less variable, this is almost equally noteworthy. The pattern of the venation of the wings of cockroaches, and the structure and form of land snails, gally-worms and decapod crustaceans were all settled in the ('arboniferous age, in a way that still remains. So were the foliage and the fructification of club-mosses and ferns. If, at any time, members of these groups branched off, so as to lay the foundation of new species, this must have been a very rare and exceptional occurrence, and one demanding even some suspension of the ordinary laws of nature. ^Ve may perhaps be content on this question to say with (iaudry,^ that it is not yet possible to " pierce the mystery that surrounds the development of the great classes of animals," or with F-of. Williamson,- that in reference to fossil plants " the time has not yet arrived for the appointment of a botanical King-at-arms and Constructor of pedigrees." We shall, how- ever, find that by abandoning mere hypothetical causes and carefully noting the order of the development and the causes in operation, so far as known, we may reach to ideas as to cause and mode, and the laws of succession, even if unable to pene- trate the mystery of origins. Another caution which a palaeontologist has occasion to give with regard to theories of life, has reference to the tendency of biologists to infer that animals and plants were introduced * " Enchainements du Monde Animal,' Paris, 1883. ^ Address before Royal Inslilution, Fel). , 18S3. WORLD-MAKIN(; 27 under embryonic forms, and at first in few and imperfect species. Facts do not substantiate this. The first appearance of leading types of life is rarely embryonic, or of the nature of immature individuals. On the contrary, they often appear in highly perfect and specialized forms, often, however, of compo- site type and expressing characters afterwards so se[)arated as to belong to higher groups. The trilobites of the Cambrian are some of them of few segments, and so far embryonic, but the greater part are many-segmented and very complex. The batrachians of the Carbon'ferous present many characters higher than those of their modern successors and now appropriated to the true reptiles. The reptiles of the Permian and Trias usurped some of the prerogatives of the mammals. The ferns, lycopods and equisetums of the Devonian and Carboniferous were, in fructification, not inferior to their modern representa- tives, and in the structure of their stems far superior. The shell- bearing cephalopods of the Palaeozoic would seem to have possessed structures now special to a higher group, that of the cuttle-fishes. The bald and contemptuous negation of these facts by Haeckel and other biologists does not tend to give geologists much confidence in their dicta. Again, we are now prepared to say that the struggle for existence, however plausible as a theory, when put before us in connection with the productiveness of animals and the few survivors of th-^'r multitudinous progeny, has not been the determining cause of the introduction of new species. The periods of rapid introduction of new forms of marine hfe were not periods of struggle, but of expansion — those periods in which the submergence of continents afforded new and large space for their extension and comfortable subsistence. In like manner, it was continental emergence that afforded the oppor- tunity for the introduction of land animals and plants. Fur- ther, in connection with this, it is now an established conclusion that the great aggressive faunas and floras of the continents mm 28 WORLD-MAKING ;■ ( have originated in the north, some of them within the arctic circle, and this in periods of exceptional warmth, when the perpetual summer sunshine of the arctic regions coexisted with a warm temperature. The testimony of the rocks thus is that not struggle but expansion furnished the requisite conditions for new forms of life, and that the periods of struggle were characterized by depauperation and extinction. But we are sometimes told that organisms are merely mechanical, and that the discussions respecting their origin have no significance any more than if they related to rocks or crystals, because they relate merely to the organism considered as a machine, and not to that which may be supposed to be more important, namely, the great determining power of mind and will. That this is a mere evasion by which we really gain nothing, will appear from a characteristic extract of an article by an eminent biologist in the new edition of the Encyclopedia Britannica, a publication which, I am sorry to say, instead of its proper ro/e as a repertory of facts, has admitted partisan papers, stating extreme and unproved speculations as if they were conclusions of science. The statement referred to is as follows : — " A mass of living protoplasm is simply a molecular machine of great complexity, the total results of the working of which, or its vital phenomena, depend on the one hand on its construction, and on the other, on the energy supplied to it ; and to speak of vitality as anything but the name for a series of operations is as if one should talk of the horologity of a clock." It would, I think, scarcely be possible to put into the same number of words a greater amoun. of unscientific assumption and unproved statement than in this sentence. Is " living protoplasm " different in any way from dead protoplasm, and if so, what causes the difference ? What is a " machine " ? Can we conceive of a self-produced or uncaused machine, or one not intended to work out some definite results ? The results of the machine in question are said to be " vital phenomena " ; WORLD-MAKING 29 ism, "? I or lults certainly most wonderful results, and greater than those of any machine man has yet been able to construct. But why *' vital " ? If there is no such thing as life, surely they are merely physical results. Can mechanical causes produce other than physical effects ? To Aristotle life was " the cause of form in organ- isms." Is not this quite as likely to be true as the converse pro- position ? If the vital phenomena depend on the " construction " of the machine, and the "energy supplied to it," whence this construction and whence this energy ? The illustration of the clock does not help us to answer this question. The construc- tion of the clock depends on its maker, and its energy is de- rived from the hand that winds it up. If we can think of a clock which no one has made, and which no one winds, a clock constructed by chance, set in harmony with the universe by chance, wound up periodically by chance, we shall then have an idea parallel to that of an organism living, yet without any vital energy or creative law ; but in such a case we should certainly have to assume some antecedent cause, whether we call it "horologity " or by some other name. Perhaps the term evolution would serve as well as any other, were it not that common sense teaches that nothing can be spontaneo:'sly evolved out of that in which it did not previously exist. There is one other unsolved problem in the study of life by the geologist to which it is still necessary to advert. This is the inability of palaeontology to fill up the gaps in the chain of being. In this respect we are constantly taunted with the im- perfection of the record, a matter so important that it merits a separate treatment ; but facts show that this is much more complete than is generally supposed. Over long periods of time and many lines of being we have a nearly continuous chain, and if this does not show the tendency desired, the fault is as likely to be in the theory as in the record. On the other hand, the abrupt and simultaneous appearance of new types in many specific and generic forms and over wide and 1'^ 30 WORLD-MAKING u> separate areas at one and the same time, is too often repeated to be accidental. Hence pala:ontologist.s, in endeavouring to establish evolution, have been obliged to assume periods of exceptional activity in the introduction of species, alternating with others of stagnation, a doctrine differing very little from that of special creation, as held by the older geologists. The attempt has lately been made to account for these breaks by the assumption that the geological record relates only to periods of submergence, and gives no information as to those of elevation. This is manifestly untrue, in so far as marine life is concerned, the periods of submergence are those in which new forms abound for very obvious reasons, already hinted ; but the periods of new forms of land and fresh-water life are those of elevation, and these have their own records and monuments, often very rich and ample, as, for example, the swamps of the Carboniferous, the transition from the great Cretaceous sub- sidence, when so much of the land of the Northern Hemisphere was submerged, to the new continents of the Tertiary, the Tertiary lake-basins of Western America, the Terraces and raised beaches of the Pleistocene. Had I time to refer in detail to the breaks in the continuity of life which cannot be explained by the imperfection of the record, I could show at least that nature in this case does advance />er saltuiu — by leaps, rather than by a slow continuous process. Many able reasoners, as Le Conte, in America, and Mivart and Collard in England, hold this view. Here, as elsewhere, a vast amount of steady conscientious work is required to enable us to solve the problems of the history of life. But if so, the more the hope for the patient student and investigator. I know nothing more chilling to re- search, or unfavourable to progress, than the promulgation of a dogmatic decision that there is nothing to be learned but a merely fortuitous and uncaused succession, amenable to no law, and only to be covered, in order to hide its shapeless and r I WORLD-MAKING uncertain proportions, by the mantle of bold and gratuitous hypothesis. So soon as we find evidence of continents and oceans ve raise the (juestion, Have these continent? existed from the first in their present position and form, or have the land and water changed places in the course of geological time? This ques- tion also deserves a separate and more detailed consideration. In reality both statements are true in a certain limited sense. On the one hand, any geological map whatever suffices to show that the general outline of the existing land began to be formed in the first and oldest crumplings of the crust. On the other hand, the greater part of the surface of the land consists of marine sediments which must have been deposited when the continents were in great part submerged, and whose materials must have been derived from land that has perished in the process, while all the continental surfaces, except, perhaps, some high peaks and ridges, have been many times submerged. Both of these apparently contradictory statements are true ; and without assuming both, it is impossible to explain the existing contours and reliefs of the surface. In exceptional cases even portions of deep sea have been elevated, as in the case of the Polycistine deposits in the West Indies ; but these exceptions are as yet scarcely sufficient to prove the rule. In the case of North America, the form of the old nucleus of Laurentian rock in the north already marks out that of the finished continent, and the successive later formations have been laid upon the edges of this, like the successive loads of earth dumped over an embankment. But in order to give the great thickness of the Palaeozoic sediments, the land must have been again and again submerged, and for long periods of time. Thus, in one sense, the continents have been fixed ; in another, they have been constantly fluctuating. Hall and Dana have well illustrated these points in so far as eastern North America s. e;. 3 r 32 WORLD-MAKING a. is concerned. Prof. Hull of the Geological Survey of Ireland has had the boldness to reduce the fluctuations of land and water, as evidenced in the British Islands, to the form of a series of maps intended to show the physical geograi)hy of eac^h successive period. The attempt is probably premature, and has been met with much adverse criticism ; but there can be no doubt that it has an element of truth. When we attempt to calculate what could have been sui)plied from the old Eozoic nucleus by decay and a(]ueous erosion, and when we take into account the greater local thickness of sediments towards the present sea-basins, we can scarcely avoid the conclusion that extensive areas once occupied by high land are now under the sea. But to ascertain the precise areas and position of these perished lands may now be impossible. In point of fact we are obliged to believe in the contempo- raneous existence in all geological periods, except perhaps the very oldest, of three sorts of areas on the surface of the earth : (i) Oceanic areas of deep sea, which must always have oc- cupied the bed of the present ocean, or parts of it ; (2) Conti- nental plateaus sometimes existing as low flats, or as higher table-lands, and sometimes submerged ; (3) Areas of plication or folding, more especially along the borders of the oceans, forming elevated lands rarely submerged and constantly afford- ing the material of sedimentary accumulations. We shall find, however, that these have changed places in a remarkable man- ner, though always in such a way that neither the life of the land nor of the waters was wholly extinguished in the process. Every geologist knows the contention which has been occasioned by the attempts to correlate the earlier Palaeozoic deposits of the Atlantic margin of North America with those forming at the same time on the interior plateau, and widi those of intervening lines of plication and igneous disturbance. Stratigraphy, lithology and fossils are all more or less at fault in dealing with these questions, and while the general nature WORLD- MAKING 33 ligher [cation [ceans, fford- |1 find, man- f the fcess. been lozoic [those wiih lance. fault lature of the problem is understood by many geologists, its solution in particular cases is still a source of apparently endless debate. The causes and mode of operation of the great movements of the earth's crust which have produced mountairi.:, plains and table-lands, are still involved in some mystery. One patent cause is the unequal settling of the crust towards the centre ; but it is not so generally understood as it should be, that the greater settlement of the ocean-bed has necessitated its pressure against the sides of the continents in the same manner that a huge ice-floe crushes a ship or a pier. The geological map of North America shows this at a glance, and impresses us with the fact that large portions of the earth's crust have not only been folded but bodily pushed back for great distances. On looking at the extreme north, we see that the great Laurentian mass of central Newfoundland has acted as a projecting pier to the space immediately west of it, and has caused the gulf of St. Lawrence to remain an undisturbed area since Palaeozoic times. Immediately to the south of this, jva Scotia and New Brunswick are folded back. Still farther south, as Guyot has shown, the old sediments have been crushed in sharp folds against the Adirondack mass, which has sheltered the table-land of the Catskills and of the great lakes. South of this again the rocks of Pennsylvania and Maryland have been driven back in a great curve to the west. Move- ments of this kind on the Pacific coast of America have been still more stupendous, as well as more recent. Dr. O. M. Dawson^ thus refers to the crushing action of the Pacific bed on the rocks of British Columbia, and this especially at two periods, the close of the Triassic and the close of the Cretace- ous : "The successive foldings and crushings which the Cor- dillera region has suffered have resulted in an actual change of position of the rocks now composing its western margin. * Trans. Royal Society of Canada, 1S90. — o jp'w ■*»iiM»t'«»!'W»i"«>ir p^ ^ 34 WOKLD-MAKING This change may have amounted since the beginning of Mesozoic time to one-third of its whole jiresent width, which would i)lace the line of the coast ranges about two degrees of longitude farther west." Here we have evidence that a tract of country 400 miles wide and consisting largely of mountain ranges and table-lands, has been crushed bodily back o\e.v two degrees of longitude ; and this applies not to British Columbia merely, but to the whole west coast from Alaska to Chili. Yet we know that any contraction of the earth's nucleus can crumple up only a very thin superficial crust, which in this .use must have slid over the pasty mass below.^ Let it be observed, however, that the whole lateral pressure of vast areas has been condensed into very narrow lines. Nothing, I think, can more forcibly snow the enormous pressure to which the edges of the continents have been exposed, and at the same time the great sinking of the hard and resisting ocean- beds. Complex and difficult to calculate though these move- ments of plication are, they are more intelligible than the apparently regular pulsations of the flat continental areas, whereby they have alternately been below and above the waters, and which must have depended on somewhat regularly recurring causes, connected either with the secular cooling of the earth or with the gradual retardation of its rotation, or with both. There is, however, good reason to believe that the suc- cessive subsidences alternated with the movements of plication, and der on upward bandings of the ocean floor, and also gradual slackening of the rotation of the earth. Th jut these changes, each successive elevation exposed the luoks for long ages to the decomposing influence of the atmosphere. Each submergence swept away and deposited as * This view is quite consistent with the practical solidity of the earth, and with the action of local expansion by heat, of settlement of areas overloaded with sediment, and of primitive or downward sliding of beds. This we shall see in the sequel. I WORLD-MAKINd 35 sediment the material accumulated by decay. Every change of elevation was accompanied with changes of climate, and with modifications of the habitats of animals and plants. Were it possible to restore accurately the physical geography of the earth in all these respects, for each geological period, the data for the solution of many difficult (juestions would be furnished. We have wandered through space and time sufficiently for one chapter, and some of the same topics must come ui) later in other connections. Let us sum up in a word. In human history we are dealing with the short lives and limited plans of man. In the making of worlds Wv, are conversant with the plans of a Creator with whom one day is as a thousand years, and a thousand years as one day. We must not measure such things by our microscopic scale of time. Nor should we fail to see that vast though the ages of the earth are, they are parts of a continuous plan, and of a plan probably reaching in space and time immeasurably beyond our earth. AV'hen we trace the long history from an incandescent fire-mist to a finished earth, and vast ages occupied by the dynasties of plant and animal life, we see not merely a mighty maze, an almost endless pro- cession of changes, but that all of these were related to one another by a chain of causes and effects leading onward to greater variety and complexity, while retaining throughout the traces of the means employed. The old rocks and the ancient lines of folding and the perished forms of Vii?. are not merely a scaffolding set up to be thrown down, but the foundation stones of a great and symmetrical structure. Is it yet com- pleted ? Who can tell ? The earth may still be young, and infinite ages of a better history may lie before it. Ri:i'ERE\CES ' : Presidential Address to the American Association for the Advancement of Science, meeting at ^Minneapolis, l8Sj. "The Story of the Eartli and Man." Nintli edition, London, 18S7. ' The references in this and succeeding chapters are exclusively to papers and works by the author, on which the several chapters are based. f-;" \ ">'*H?*»**M«»'-'« THE IMPERFECTION OF THE GEOLOGICAL RECORD. DEDICATED TO THE MEMORY OF JOACHIN BARRANDE, One oi- THE most successful Labourers IN THE Completion of the Histopv ok Lh k IN its earlier Stages. \ ' i Hi Nature ok the Lmi>eri'i;ction — Questions as to its ARISINC FROM WaNT OK CONTINUITY, KROM I.ACK OK TrESERVATION, KROM iMlM'.UKEfl' COI.I.ECTINO. EX- AMPLES—LaND Snails, Cart-onikerois Hatrachians, Pal.i:ozou: Sponges, Pli:istocene Smells, Devonian AND Carboniferous Plants — Compara iive Perkec^ TioN IN THE Case ok Mapixe Shells, etc.— Possip.le Cambrian Sijuids — Questions as lo \\'ant ok First Chapters ok thi'. Record - PRAtiicAi. ''oxclusions \i ") ITS K OK -X- lANS. NIAN KIX'^ IV.LK IRST l\S V a, y. s ^ o O •vj o s 4J ►*; ^^ •v.k "oj •^ 3 « O^ "^ g o 'n u. ui C; O »* A u P ■4-» ■f. «r 3 y. * **» < 'sj CHAPTER III. THE IMPERFECTION OF THE GEOLOGICAL RECORD. COMPLAINTS of tl c .nperfection of the geological record are rife among those biologists who expect to find continuous series of fossils representing the gradual trans- mutation of speci^^ , No doubt these gaps are in some cases portentous, and unfortunately they often occur just where it is most essential to certain general conclusions that they should be filled up. Instead, however, of making vague lamentations on the subject, it is well to inquire to what causes these gaps may be due, to what extent they invalidate the completeness of geological history for scientific purposes, and how they may best be filled. Here we may first remark that it is not so much the physical record of geology that is imperfect as the organic record, l-^ver since the time of Hutton and Playfair we have learned that the processes of mineral detrition and deposition are contin- uous, and have been so throughout geological time. The erosion of the land is constantly going on, every shower carries its tribute of earthy matter toward the sea, and every wave that strikes against a beach or cliff does some work toward the grinding of shells, pebbles or stone. Thus, everywhere around our continents there is a continuous deposition of beds of earthy matter, and it is this which, when elevated into \w.\s land, has given us our chronological series of geological forma- tions. True, the elevating process is not continuous, Init, so 39 M 40 IMPERFECTION' OF THE GEOLOGICAL RECORD far as we know, intermittent ; but it has been so often repeated that we have no reason to doubt that the wasting continents afford a complete series of aqu(^ous deposits, since the time when the dry land first appeared. In recent years the Challenger expedition and similar dredg- ings have informed us of still another continuity of deposition in the depths of the ocean. There, where no detritus from the land, or only a very little fine volcanic ash or pumice has ever reached, we have, going on from age to age, a deposit of the hard parts of abyssal animals and of those that swim in the open sea ; so that if it were possible to bore or sink a shaft in some parts of the ocean, we should find not only a continu- ous bed, but a continuous series of pelagic life from the Laurcntian to the present day. Thus we have continuous physical records, could we but reach or completely put them together, and eliminate the disturbing influence of merely local vicissitudes. It is when we begin to search the geological formations for fossils, that imperfection in our record first becomes painfully manifest. In the case of many groups of marine animals, as, for example, the shell-fish and the corals, and I may add the bivalve crustaceans, so admirably worked up by my friend Prof. Rupert Jones, we have very complete series. With the land snails the case is altogether different. As stated in an- other paper of this series, a few species of these animals appear in the later Paloiozoic age, and after that they have no suc- cessors known to us in all the great periods covered by the Permian, the Trias, and the earlier Jurassic. A few air-breath- ing water-snails appear in the upper Jurassic, and true land snails are not met with again until the Tertiary. Were there no land snails in this vast lapse of time? Have we two suc- cessive creations, so to speak, of these creatures at distant intervals ? Were they only diminished in numbers and distri- bution in the intervening lime? Is the hiatus owing merely IMPERFECTION OF THE CEOLOCICAL RECORD 4 1 to the unlikelihood of such shells being preserved? Or is it owing to the lack of diligence and care in collecting ? In this particular case we are, no doubt, disposed to say 1'. it the series must have been continuous. But we cannot be sure of this. In whatever way a few species of land snails were so early introduced in the lime of the Devonian or of the Coal formation, if from physical vicissitudes or lack of proper pabulum they became extinct, there is no reason known to us why, when circumstances again became favourable, they should not be reintroduced in the same manner as at first, whether by development from allied types or otherwise. The fact that the few Devonian and Carboniferous species are very like those diat still exist, perhaps makes against this supposition, but does not exclude it. If we suppose that new forms of life of low grade are introduced from time to time in the course of the geological ages, and if we adopt the L^arwinian hypo- thesis of evolution, we arrive, as Naegeli has so well pointed out, at the strange paradox, that the highest forms of life must be the oldest of all, since they will be the descendants of the earliest of the lower animals, whereas the animals now of low grade may have been introduced later, and may not have had time to improve. But all our attempts to reduce nature to one philosophic expression necessarily lead to such paradoxes. On the other hand, the chances of the preservation of land snails in aqueous deposits are vastly less than those in favour of the preservation of aquatic species. The first Carboniferous species found ^ had been preserved in the very exceptional circumstances afforded by the existence of hollow trunks of Sigillarias on the borders of the Coal formation flats, and the others subsequently found were in beds no doubt receiving the drainage of neighbouring land areas. Still it is not un- common on the modern sea-shore, anywhere near the mouths of rivers, to find a few freshwater shells here and there. The ' Pupa vctusta of the Nova Scotia coal formation. 42 IMPERFECTION OF THE GEOLOGICAL RECORD • I carbonaceous beds of the Trias, the fossil soils of the Portland series, the estuarine Wealden beds would seem to be as favour- ably situated as those of the coal formation for preserving land shells, though possil)ly the flora of the Mesozoic was less suit- able for feeding such creatures than that of the Coal period, and they may consequently have become few and local. After all, perhaps more diligent collecting and more numerous col- lectors might succeed, and may succeed in the future, in filling this and similar gaps. It is a great mistake to suppose that discoveries of this kind are made by chance. It is only by the careful and painstaking examination of much material that the gaps in the geological record can be filled up, and I propose in the sequel of this article to note a few instances, in a country where the range of territory is altogether out of proportion to the number of observers, and which have come within my own knowledge. It was not altogether by accident that Sir C. Lyell and the writer discovered a few reptilian bones and a land snail in breaking up portions of the material filling an erect Sigillaria in the South Joggins coal measures. We were engaged in a deliberate survey of the section, to ascertain as far as might be the conditions of accumulation of coal, and one point which occurred to us was to inquire as to the circumstances of preservation of stumps of forest trees in an erect position, to trace their roots into the soils on which they stood, and to ascertain the circumstances in which they had been buried, had decayed, and had been filled with mineral matter. It was in questioning these erect trees on such subjects — and this not without some digging and hammering — that we made the dis- covery referred to. But we found such remains only in one tree, and they were very imperfect, and indicated only two species of batrachians and one land snail. There the discovery might have rested. But I undertook to follow it up. In successive visits to the TMPERFFXTIOX OF THE GEOLOGICAL RECORD 43 coast, a large number of trees standing in the cliff and reefs, or fallen to the shore, were broken up and examined, the result being to discover that, with one unimportant exception, the productive trees were confined to one of the beds at Coal Mine Point, that from which the original specimens had been obtained. Attention was accordingly concentrated on this, and as many as thirty trees were at different times extracted from it, of which rather more than one-half proved more or less productive. By these means bones representing about sixty specimens and twelve species were extracted, besides numerous remains of land shells, millipedes, and scorpions. In this way a very complete idea was obtained of the land life, or at least of the smaller land animals, of this portion of the coal formation of Nova Scotia. It is not too much to say that if similar repositories could be found in the succeeding forma- tions, and properly worked when found, our record of the history of land quadrupeds might be made very complete. When in 1855 I changed my residence from Nova Scotia to Montreal, and so was removed to some distance from the carboniferous rocks which I had been accustomed to study, I naturally felt somewhat out of place in a Cambro-Silurian dis- trict, more especially as my friend Billings had already almost exhausted its fossils. I found, however, a congenial field in the Pleistocene shell beds ; more especially as I had given some attention to recent marine animals when on the sea coast. The very perfect series of Pleistocene deposits in the St. Lawrence valley locally contain marine shells from the bottom of the till or boulder clay up to the overlying sands and gravels. The assemblage was a more boreal one than that on the coast of Nova Scotia, though many of the species were the saine, and both the climatal and bathymetriil conditions differed in different parts of the Pleistocene beds themselves. The gap in the record here could at that time be filled up onb- by col- lecting recent shells. In addition to what could be obtained 44 IMI'ERFKCTION OK Tllli GKOLOGK'AL RECORD i I by exchanging with naturahsts who had c-ollectcd in (Irecnland, Labrador, and Norway, I employed myself, summer after summer, in dredging both on the south and north shore of the St. Lawrence, until able at length to discover in a living state, but under different conditions as to temperature and dei)th, nearly every species found in the beds on the laiid, from the lower boulder clay to the top of the formation, and from the sea-level to the beds six hundred feet high on the hills. Not only so : 1 could ascertain in certain places and conditions all the peculiar varieties of the species, and the special modes of life which they indicated. Thus, in the cases of the Peter Redpath Museum, and in notes on the Post- pliocene of Canada, the gap between the Modern and the Glacial age was completely filled up in so far as Canadian marine species are concerned. The net result was, as 1 have elsewhere stated, that no change other than varietal had occurred. In studying the fossil plants of the Carboniferous, so abundant in the fine exposures of the coal formation in Nova Scotia, two defects struck me painfully. One was the fragmentary and imperfect state of the specimens procurable. Another was the question, \\^hat preceded these plants in the older rocks? The first of these was to be met only by thorough exploration. When a fragment of a plant was disclosed it was necessary to inquire if more existed in the same bed, and to dig, or blast away or break up the rock, until some remaining ])ortions were disclosed. In this way it has been possible to obtain entire specimens of many trees of the Carboniferous ; and to such an extent has the laborious and somewhat costly process been effectual, that more species of carboniferous trees are probably known in their entire forms from the Coal forma- tions of Nova Scotia than from any other part of the world. I have been amused to find that so little are experiences of this kind known to some of my confreres abroad, that they IMPERFECTION OF THE CIEOLOGICAL RECORD 45 are disposed to look with scepticism on the information obtained by this laborious but certain process, and to suppose that they are being presented with imaginary "restorations." I think it right here to copy a remark of a German botanist, who has felt himself called to criticise my work : *' Dawson's description of the genus {Psilophyton) rests chiefly on the impression made on him in his repeated researches," etc. " He puts us off with an account of the general idea which he has drawn from the study of them." This is the remark of a closet naturalist, with reference to the kind of work above referred to, which, of course, cannot be represented in its entirety in figures or hand specimens.^ As to the precursors of the Carboniferous flora, in default of information already acquired, I proceeded to question the Erian or Devonian rocks of Canada, in which Sir William Logan had already found remains of plants which had not, however, been studied or described. Laboriously coasting along the cliffs of Gaspe and the Baie des Chaleurs, digging into the sandstones of Eastern Maine, and studying the plants collected by the New York Survey, I began to find that there was a rich Devonian flora, and that, like that of the Carboni- ferous, it presented different stages from the base to the summit of the formation. But here a great advance was made in a somewhat unexpected way. My then young friends, the late Prof. Hartt and Mr. Matthew, of St. John, had found a few remains of plants in the Devonian, or at least pre-Carboniferous beds of St. John, which were placed in my hands for descrip- tion. They were so novel and curious that inquiry was stimu- lated, and these gentlemen, with some friends of similar tastes, explored the shales exposed in the reefs near St. John, and when they found the more productive beds, broke them up by * Solms-Laubacli, " Fossil Botany." A pretentious book, which should not have been translated into English without thorough revision and correction. S. E. 4 .^-J m m 46 IMPERFECTION OF THE GEOLOGICAL RECORD II 11 U actual quarrying operations in such a way that they soon obtained the rirhc.>c Devonian plant collections ever known. I think I niiiy truly say that these young and enthusiastic explorers worked the St. John plant-beds in a manner pre- viously unexampled in the world. Their researches were not only thus rewarded, but incidentally they discovered the first known Devonian insects, which could not have been fountl by a less painstaking process, and one of them discovered what I believe to be the oldest known land shell. Still more, their studies led to the separation from the Devonian beds of the Underlying Cambrian slates, previously confounded with them ; and this, followed up by the able and earnest work of Mr. Matthew, has carried back our knowledge of the older rocks in Canada several stages, or as far as the earliest Cambrian previously known in Europe, but not before fully recognised in America, and has discovered in these old rocks the precursors of many forms of life not previously traced so far back. The moral of these statements of fact is that the imper- fections of the record will yield only to patient and painstaking work, and that much is in the power of local amateurs. I would enforce this last statement by a reference to a little research, in which I have happened to take part at a summer resort on the Lower St. Lawrence, at which I have from time to time spent a few restful vacation weeks. Little Metis is on the Quebec Oroup of Sir William Logan, that peculiar local representative of the lower part of the Cambro-Silurian and Upper Cambrian formations which stretches along the south side of the St. Lawrence all the way from Quebec to Cape Rosier, near Gaspe, a distance of five hundred miles. 'Hiis great series of rocks is a jumble of deposits belonging at that early time to the marginal area of what is no .v the American continent, and indicating the action not merely of ordinary causes of aqueous deposit, but of violent volcanic ejections, IMPERFECTION OF THE GEOLOGICAL UECOKD 47 accompanied perhaps by earthquake waves, and not improb- ably by the action of heavy coast ice. The result is that mud rocks now in the form of black, grey, and red shales and slates alternate with thick and irregular beds of hard sandstone, sometimes so coarse that it resembles the angular di'hris of the first treatment of quartz in a crusher. With these sandstones are thick and still more irregular conglomerates formed of pebbles and boulders of all sizes, up to several feet in diameter, some of which are of older limestones containing Cambrian fossils, while others are of cpiartzite or of igneous or volcanic rocks. The whole formation, as presented at Metis, is of the most unpromising character as regards fossils, and after visiting the place for ten years, and taking many long walks along the shore and into the interior, and scrutinising every exposure, I had found nothing more interesting than a few fragments of graptolites, little zoophytes, ancient representatives of our sea mosses, and which are quite characteristic of several portions of the Quebec Group. With these were some marks of fucoids and tracks or burrows of worms. 'I'he explorers of the (leological Survey had been equally unsuccessful. Quite accidentally a new light broke upon these unpromis- ing rocks. My friend, Dr. Harrington, strolling one day on the shore, sat down to rest on a stone, and picked up a piece of black slate lying at his feet. He noticed on it some faintly traced lines which seemed peculiar. He put it in his pocket and showed it to me. On examination with a lens it proved to have on it a few spicules of a hexactinellid sponge— little crosses forming a sort of mesh or lattice-work similar to that which Salter had many years before found in the Cambrian rocks of Wales, and had named Protospongia — the first sponge. The discovery seemed worth following up, and we took an early opportunity of proceeding to the place, where, after some search, we succeeded in tracing the loose pieces to a ledge of r^j m It! If 48 IMI'ERFECrKJN OK TIIIC (ilOOLOGICAL RECORD shale on the beach, wlierc there was a Httlc band, only about an inch thick, stored with remains ofs[)ongcs, a small bivalve shell and a slender branching seaweed. This was one small layer in reefs of slate more than one hundred feet thick. We sub- seijucntly found two other thin layers, but less productive. Tools and workmen were i)rocured, and we [)rocecded to (juarry in the reef, taking out at low tide as large slabs as possible of the most productive layer, and carefully splitting these up. The results, as [)ublished in the Transactions of the Royal Society of Canada,^ show more than twelve species of siliceous sponges belonging to six genera, besides fragments indicating other species, and all of these living at one time on a very limited space of what is practically a single surface of muddy sea-bottom.^ 'J'he specimens show the parts of these ancient sponges nuich more [)crfectly than they were previously known, and indeed, enable many of them to be perfectly re- stored. They for the first time connect the modern siliceous s[)onges of the deei) sea with tlujse tiiat flourished on the old sea-bottom of the early Cambro-Silurian, and thus bridge over a great gap in the history of this low form of life, showing that the [)rinciples of construction embodied in the remarkable and beautiful siliceous sponges, like I'Aiplectella, the " Venus llower-basket," now dredged from the deep sea, were already l)erfectly carried out in this far-back beginning of life. This little discovery further indicates that jjortions of the older Pakeozoic sea-bottoms were as well stored with a varied sponge life as those of any part of the modern ocean. 1 figure ^ a number of species, remains of all of which may be gathered from a few yards of a single surface at Little Metis. The multitude of interesting details embodied in all this it is impossible to enter into here, but may be judged of from ' AddUional collections made in 1892 show two or three ailditional species, one of them the type of a new and remarkable genus. * 1889, section iv. p. 39. Frontispiece to chapter. old over that able onus ready This Ider aried 1 ly be let is. i it is from IMPEkl'ECTION OF TIIK (;i:OLOGIC/CT;-.KiiCOKlJ- ^rr> -^ ?, Os h „..._.. .^ ._., '/ the forms reproduced. 'I'hesc examples tend to slunv tlint.thc -^fi imperfection of the record may not depend on the record ilVwif, but on the incom[)letcne.ss of our work. We must make la|;ge allowance for im[)erfect collecting, and especially U)r the too l)rcvalent habit of remaining content with few and inconn)lete specimens, and of grudging the time and labour necessary to explore thoroughly the contents of special beds, and to work out all the j)arls of forms found more or less in fragments. The i)oint of all liis at ])resent is that [)alicnt w(jrk is needed lo fill u[) the breaks in our record. A collector |)assing along the shore at Metis might have |)i(ked u[) a fragment oi a fossil sponge, and recorded it as a fossil, or j)ossil)ly described IIk- fragment. This fact alone would ha\e been \ahiablr, but to make it bear its full fruit it was necessary to trace the fragment to its source, and then to s{)en(l time and labour in extracting^ from the stul>born rock the story it had to tell. Instances of this kind crowd on my memory as coming within my o^vn r\- |)('rience and obser\"ation. It is hopeful to think th.il tin' re- ( ord is da-l\' becoming less im[)erfect ; it is stinuilating to know that so much is onl)' waiting for investigation. The his lory never can be abs(;lulely com[)Iele. I'rac'ically, to us il is iiifmile. \'et ewry series of facts known may be coni|ilele in itself for certain purposes, ho\ve\er many gaps there may be in the j.tory. I'A'en if we cannot fmd a continuous series )»e tween the sn lils o( the Ca/ SorA-^y of Canada, iSoo! Resume of the Carboniferous Land SIcs of North America '' • Amencan Journal of Science, iSSo. "Burrows and Tracks of L,- vejlebrate An.mals": /,..;-../ Geological Society of London, ,890. Aotes on the I'l -stocene of Canada " : Canadian Naturalist, ,870. Air-breathers of the Coal Period " : Ibid., 1S63. \i ) m t THE HISTORY OF THE NORTH ATLANTIC, DEDICATED TO THE MEMOR^• OF PROF. JOHN IMULLIPS, OF OXFORD, OXK ,.r THK MUST Am.K. KAKNKVr, AM. (;kX,AL OF English GKoi.ociisTs ; AXU OF OTHEK Em.NE:-t..r:^.--- I - '.- ■•"slS- • ll:.';;::n';::n:...„ ^i ^^-'0:.v;LiiB?H^::;;:ii-!!i!iii!!i!t;!!J=;'/;;.: '.■;r;; ^ .?K;.'';«f»!»" /■ft. ■-:t^iW:---"' rcrv ■ ■. ■ . . .- • ■■ 'I. •• ■•'!!:!,''■■«<•«•«■''-•■■«••]£;:.!':.■ "J*:. ;i:ii!iii ;pvi.«;:'x' SwiiiiMiii''-:: ;^ t I >. V^^^-' Ji ... ■.:,;::.-|.S??-;.|,./^'; : : :. iN>' w--, .■..■;i;.-.u.;:.;. i t I \ :: ■ > *n Vj\ I-./ «>*<> > o 8 •^ ^ n • v^ fi ■.*". oj X i* -*-» •— • 3 "J n U4 tfi o C t/J '■$■ OJ o ^ r^ rt /. , r^ •% CJ ^ 5; L /', ■^i -i; o 'A 1/ :■: ,■ 1- -^■% - '\, , \ Ecn z^''. 1 s s o iiiS 'I'V'hu JU. I/! ■*-' &. 3 0) X "^ u t/3 u "-» A *-• < ^ ^ V-( •—1 H -• O ;^ !i] w4 »*^ H U^ o Ch < — f^ CHAPTER IV. THE HISTORY OF THE NORTH ATLANTIC. T HAD the pleasure of being present at the meeting of the A British Association at Birmingham, in 1865 : a meeting attended by an unusually large number of eminent geologists under the presidency of my friend Phillips. I had the further p easure of being his successor at the meeting \n the same pace, in 1886; and the subject of this chapter is that to which I directed the attention of the Association in my Presidential address. I fear it is a feeble and imperfect utter- ance compared with that which might have been given forth by any of the great men present in 1865, and who have since left us, could they have spoken with the added knowledge of the mtervening twenty years. The geological history of the Atlantic appeared to be a suitable subject for a trans-Atlantic president, and to a Society which had vindicated its claim to be British in the widest •sense by holding a meeting in Canada, while it was also meditating a visit to Australia-a visit not yet accomplished but in which It may now meet with a worthy daughter in the Australian Association formed since the meeting of 1886. The subject is also one carrying our thoughts very far back in geological time, and connecting itself with some of the latest and most important discussions and discoveries in the science of the earth, furnishing, indeed, too many salient points to be profitably occupied in a single chapter. If we imagine an observer contemplating the earth from a 57 1 , 58 Till-: HISTORY 01' THE NORTH ATLANTIC f ^i i 'h convenient distance in space, and scrutinizing its features as it rolls before him, we may suppose him to be struck with the fact that eleven-sixteenths of its surface are cove"cd with water, and that the land is so unequally distributed that from one point of view he would see a hemisphere almost exclusively oceanic, while nearly the whole of the dry land is gathered in the opposite hemisphere. He might observe that large portions of the great oceanic areas of the Pacific and Antarctic Oceans are dotted with islands — like a shallow pool with stones rising above its surface — as if the general depth were small in com- parison with the area. Other portions of these oceans he might infer, from the colour of the water and the absence of islands, cover deep depressions in the earth's surface. He might also notice that a mass or belt of land surrounds each pole, and that the northern ring sends off to the soutliward three vast tongues of land and of mountain chains, terminating respectively in South America, South Africa, and Australia, towards which feebler and insular processes are given off by the antarctic cont-'^iental mass. This, as some geographers have observed, ^ gives a rudely three-ribbed aspect to the earth, though two of the ribs are crowded together, and form the Eurasian mass or double continent, while the third is isolated in the single continent of America. He might also observe that the northern girdle is cut across, so that the Atlantic opens by a wide space into the Arctic Sea, while the Pacific is contracted toward the north, but confluent with the Antarctic Ocean, The Atlantic is also relatively deeper and less cum- bered with islands than the Pacific, which has the highest ridges near its shores, constituting what some visitors to the Pacific coast of America have not inaptly called the " back of the world," while the wider slopes face the narrower ocean. The Pacific and Atlantic, though both depressions or flat- * Dana, •' Manual of Geology," introductory part. CJreen, •' Vestiges of a Molten Globe," has summed up these facts. THE HISTORY OF THE NORTH ATLANTIC 50 tenings of the earth, are, as we shall find, different in age, character, and conditions; and the Atlantic, though the smaller, is the older, and, from the geological point of view, in some respects, the more important of the two ; while, by virtue of lis lower borders and gentler slope, it is, though the smaller basin, the recipient '" the greater rivers, and of a j)r()p(irti()nately great amount of the drainage of the land.' If our imaginary observer had the means of knowing any- thing of the rock formations of the continents, he would notice that those bounding the North Atlantic are, in general, of great age — some belonging to the Laurentian system. On the other hand, he would see that many of the mountain ranges along the Pacific are comparatively new, and that modern igneous action occurs in connection with them. 'Thus he might see in the Atlantic, though comparatively narrow, a more ancient feature of the earth's surface ; while the Pacific belongs to more modern times, l^ut he would note, in con- nection with this, that the oldest rocks of the great continental masses are mostly toward their northern ends ; and that the borders of the northern ring of land, and certain ridges en- tending southward from it, constitute the most ancient and permanent elevations of the earth's crust, though now greatly surpassed by mountains of more recent age nearer the equator, so that the continents of the northern hemisphere seem to have grown progressively from north to south. If the attention of our observer were directed to more modern processes, he might notice th? while the antarctic continent freely discharges its burden of ice to the ocean north of it, the arctic ice has fewer outlets, and that it mainly dis- charges itself through the North Atlantic, where also the great mass of Greenland stands as a huge condenser and cooler, ^ Mr. Mellard Reade, in two Presidential addresses before the Geo- logical Society of Liverpool, has ilhistrated this point and its geological consequences. S. E. 5 ' 6o THE HISTORY OF THR NORTH ATLANTIC I ' I''' si : £• I' '^ I unexampled elsewhere in the world, throwing every spring an immense (quantity of iee into the North Atlantic, and more es[)ecially into its western part. On the other hand, he might learn from the driftage of weed and the colour of the water, that the present great continuous extension and lOrm of the American continent tend to throw northward a powerful branch of the equatorial current, which, revolving around the North Atlantic, counteracts the great flow of ice which otherwise would condemn it to a perpetual winter. Further, such an observer would not fail to notice that the ridges which lie along the edges of the oceans and the ebul- litions of igneous matter which proceed, or have proceeded from them, are conseqiiences of the settling downward of the great oceanic depressions, a settling ever intensified by their receiving more and more of deposit on their surfaces ; and that this squeezing upward of the borders of these depressions into folds has been followed or alternated with elevations and depressions without any such folding, and proceeding from other causes. On the whole, it would be apparent that these actions are more vigorous now at the margins of the Pacific area, while the Atlantic is backed by very old foldings, or by plains and slopes from which it has, so to speak, dried away without any internal movement. Thus it would appear that the Pacific i^s the great centre of earth-movemjnt, while the Atlantic trench is the more potent regulator of temperature, and the ocean most likely to be severel> affected in this respect by small changes of its neighbouring land. Last of all, an observer, such as I have supposed, would see that "^he oceans are the producer' of moisture and the conveyors of heat to the northern regions of the world, and that in this respect and in the immense condensation and delivery of ice at its north end, the Atlantic is by far the more active, though the smaller of the two. So much could be learned by an extra-mundane observer ; i THE HISTORY OF THE NORTH ATLANTIC 6l but unless he had also enjoyed opportunities of studying the rocks of the earth in detail and close at hand, or had been favoured by some mundane friend with a perusal of " I yell's Elements," or "Dana's Manual," he would not be able to ap- preciate as we can the changes which the Atlantic has seen in geological time, and in which it has been a main factor. Nor could he learn from such superficial observation certain secrets of the deep sea, which have been unveiled by the soundin- lead, themequalitiesof the ocean basin, its few profound depths'" like mverted mountains or table-lands, its vast nearly flat abyssmal floor, and the sudden rise of this to the hundred fathom hne, forming a terrace or shelf around the sides of the continents. These features, roughly represented in the map prefixed, he would be unable to perceive. l^efore leaving this broad survey, we may make one further remark. An observer, looking at th.^ earth from without, would notice that the margins of the Atlantic and the main lines of direction of its mountain chains are north-east and south-west, and north-west and south-east, as if some early causes had determined the occurrence of elevations alon- great circles of the earth's surface tangent to the polar circles" \Ve are invited by the preceding general glance at the surface of the earth to ask certain questions respecting the Atlantic (i) What has at first determined its position and form? (2) What changes has it experienced in the lapse of geological time ? (^) What relations have these changes borne to the development of life on the land and in the water? (4) \\hat IS its probable future ? Before attempting to answer these (luestions, which I shall not take up formally in suca^ssion, but rather in connection with each other, it is necessary to state, as briefly as possible certain general conclusions respecting the interior of the earth' It IS popu'ir^> supposed that we know nothing of this beyond a superf 1 crust perhaps averaging 50,000 to 100,000 feet in 62 THE HISTORY OF THE NORTH ATLANTIC h 1 1 thickness. It is true we have no means of exploration in the earth's interior, but the conjoined labours of physicists have now proceeded sufficiently far to throw much inferential light on the subject, and to enable us to make some general affirma- tions with certainty ; and these it is the more necessary to state distinctly, since they are often treated as mere subjects of speculation and fruitless discussion. (i) Since the dawn of geological science, it has been evi- dent that the crust on which we live must be supported on a plastic or partially liquid mass of heated rock, approximately uniform in quality under the whole of its area. This is a legitimate conclusion from the wide distribution of volcanic phenomena, and f*rom the fact that the ejections of volcanoes, while locally of various kinds, are similar in every part of the world. It led to the old idea of a fluid interior of the earth, but this seems now generally abandoned, and this interior heated and plastic layer is regarded as merely an under-crust, resting on a solid nucleus. ^ (2) We have reason to believe, as the result of astronomical investigations,^ that, notwithstanding the plasticity or liquidity of the under-crust, the mass of the earth — its nucleus as we may call it — is practically solid and of great density and hardness. Thus we have the apparent paradox of a solid yet fluid earth ; solid in its astronomical relations, liquid or ' I do not propose to express any definite opinion as to this question, as cither conchision will satisfy the demands of geology. It would seem, however, that astronomers now admit a slight periodical deformation of the crust. See Lord Kelvin's Anniversary Address to Royal Society, 1892. 2 Hopkins, Mallet, Lord Kelvin, and Prof. Cr. II. Darwin maintain the solidity and rigidity of the earth on astronomical grounds ; but different conclusions have been reached by Fisher, Hennesey, Delaunay, and Airy. In America, Hunt, Barnard and Crosby, Dutton, Le Conte and Wadsworth have discussed these questions. Bonney has suggested that a mass may be slowly mobile under long-continued pressure, while rigid with reference to more sudden movements. THE HISTORY OF THE NORTH ATLANTIC 63 plastic for the purposes of volcanic action and superficial move- ments. (3) Tlie plastic sub-crust is not in a state of dry igneous fusion, but in that condition of ac^ueo-igneous or hydrothermic fusion which arises from the action of heat on moist substances, and which may either be regarded as a fusion or as a species of solution at a very high temperature. This we learn from the phenomena of volcanic action, and from the composition of the volcanic and plutonic rocks, as well as from such chemical experiments as those of Daubree, and of Tilden, and Shenstone. ^ It follows that water or steam, as well as rocky matter, may be ejected from the under-crust. (4) The interior sub-crust is not perfectly homogeneous, but may be roughly divided into two layers or magmas, as they have been called ; an upper, highly silicious or acidic, of low specific gravity and light-coloured, and corresponding to such kinds of plutonic and volcanic rocks as granite and trachyte ; and a lower, less silicious or more basic, more dense, and more highly charged vith iron, and corres[)onding to such igneous rocks as the doled tes, basalts, and kindred lavas. It is interesting here to note that this (-onclusion, elaborated by Durocher and Von \Valtershausen, and usually connected with their names, appears to have been fust announced by John Phillips, in his " Cicological Manual," and as a mere common- sense deduction from the observed phenomena of volcanic action and the probable results of the gradual cooling of the earth. It receives striking confirmation from the observed succession of acidic and basic volcanic rocks of all geological periods and in all localities. It would even seem, from recent spectroscopic investigations of Lockyer, that there is evidence of a similar succession of magmas in the heavenly l)odies, and the discovery by Nordenskiold of native iron in (Ireenland * Phil. 7 rails., 1884. Also Crosby in Proc. Boston Soi. Nat. Ilist.^ 1S83. f; I 64 THE HISTORY OF THE NORTH ATLANTIC basalts, affords a probability that the inner magma is in part metallic, and possibly, that vast masses of unoxidised metals exist in the central portion of the earth. (5) Where rents or fissures form in the upper crust, the material of the lower crust is forced upward by the pressure of the less supported portions of the former, giving rise to volcanic phenomena either of an explosive or quiet character, as may be determined by contact with water. The underlying material may also be carried to the surface by the agency of heated water, producing those quiet discharges which Hunt has named crenitic. It is to be observed here that explosive volcanic phenomena, and the formation of cones, are, as Prestwich has well remarked, characteristic of an old and thickened crust ; quiet ejection from fissures and hydro- thermal action may have been more common in earlier periods and with a thinner over-crust. This is an important con- sideration with reference to those earlier ages referred to in chapter second. (6) The contraction of the earth's interior by cooling and by the emission of material from below the over-crust, has caused this crust to press downward, and therefore laterally, and so to effect great bends, folds, and plications ; and these, modified subsequently by surface denudation, and the piling of sediments on portions of the crust, constitute mountain chains and continental plateaus. As Hall long ago pointed out,^ such lines of folding have been produced more especially where thick sediments had been laid down on the sea-bottom, and where, in consequence, internal expansion of the crust had occurred from heating below. Thus we have here another apparent paradox, namely, that the elevations of the earth's crust occur in the places where the greatest burden of de- * Hall (American Association Address, J 857, subsequently republislicd, with additions, as "Contributions to the Geological History of the American Continent"), Mallet, Rogers, Dana, La Conte, etc. #, ^ I » ■ fcWWi TIIIL HISTORY OF THE NORTH ATLAXTIC 65 tritushas been laid down upon it, and where, conseciiiently, the crust has been softened and depressed. We must beware, in this connection, of exaggerated notions of the extent of con- traction and of crumpling required to form mountains. Bonney has well shown, in lectures delivered at the London Institu- tion, that an amount of contraction, almost inappreciable in comparison with the diameter of the earth, would be sufficient ; and that, as the greatest mountain chains are less than .jioth of the earth's radius in height, they would, on an artificial globe a foot in diameter, be no more important than the slight inequalities that might result from the paper gores overlapping each other at the edges. This thinness of the crushed crust agrees with the deductions of physical science as to the shallowness of the superficial layer of compression in a cooling globe. It is perhaps not more than five miles in thickness. A singular proof of this is seen by the extension of straight cracks filled with volcanic rock in the Laurentian districts of Canada.^ The beds of gneiss and associated rocks are folded and crumpled in a most complex manner, yet they are crossed by these faults, as a crack in a board may tear a sheet of paper or a thin veneer glued on it. ^\'e thus see that the crumpled Laurentian crust was very thin, while the uncrushed sub-crust determined the line of fracture. (7) The crushing and sliding of the over-crust implied in these movements raise some serious (questions of a physical character. One of these relates to the rapidity or slowness of such movements, and the consequent degree of intensity of the heat developed, as a possible cause of metamorphism of rocks. Another has reference to the possibility of changes in the equilibrium of the earth itself, as resulting froni local collapse and ridging. These questions in connection with the ' As, for instance, the great dyke lunniiig nearly in a straight line from near St Jerome along the Ottawa to Templeton, on the Ottawa, and be- yond, a distance of more tlian a hundred niles. I r 66 THE HISTORY OF THE NORTH ATLANTIC f I lif 1^ present dissociation of the axis of rotation from the magnetic poles, and witii changes of climate, have attracted some atten- tion,* and probably deserve further consideration on the part of physicists. In so far as geological evidence is concerned, it would seem that the general association of crumpling with metamorphism indicates a certain rapidity in the process of mountain-making, and consequent development of heat ; and the arrangement of the older rocks around the Arctic basin for- bids us from assuming any extensive movement of the axis of rotation, though it does not exclude changes to a limited extent. (8) It appears from the above that mountain? and conti- nental elevations may be of three kinds, (a) They may con- sist of material thrown out of volcanic rents, like earth out of a mole burrow. Mountains like Vesuvius and .Etna are of this kind. {/>) They may be parts of wide ridges or chains variously cut and modified by rains and rivers. The Lebanon and the Catskill Mountains are cases in point. (/) They may bo lines of crumpling by lateral pressure. The greatest moun- tains, like the Cordillera, the Alps, and the Appalachians are of this kind, and such mountains may represent lateral pressure occurring at various times, and whose results have been greatly modified subsequently. I wish to formulate these principles as distinctly as possible, and as the result of all the long series of observations, calcu- lations, and discussions since the time of Werner and Hutton, and in which a vast number of able physicists and naturalists have borne a part, because they may be considered as certain deductions from our actual knowledge, and because they lie at the foundation of a rational physical geology. We may roughly popularise these deductions by comparing the earth to a drupe or stone-fruit, such as a plum or peach ' See rcccrit papers of Uldhnm and Fisher, in Ccv/o^icul A/a^'er, shortly glance at the changes of the three kinds of surface already referred to. The bed of the ocean seems to have remained, on the whole, abyssal ; but there were probably periods when those shallow reaches of the Atlantic which stretch across its most northern portion, and partly separate it from the Arctic basin, presented connecting coasts or continuous chains of islands sufficient to permit animals and plants to pass over.^ At certain periods also there were, not unlikely, groups of volcanic islands, like the Azores, in the temperate or tropical Atlantic. More especially might this be the case in that early time when it was more like the present Pacific ; and the line of the great volcanic belt of the Mediterranean, the mid-Atlantic banks, the Azores and the West Ipdia Islands point to the possibility of such partial con- nections. These were stepping stones, so to speak, over which land organisms might cross, and some of these may be con- nected with the fabulous or pre-historic Atlantis. In the Palceozoic period, the distinctions already referred to. into continental plateaus, mountain ridges, and ocean depths, were first developed, and we find, already, great masses of sedi- ment accumulating on the seaward sides of the old Laurentian ridges, and internal deposits thinning away from these ridges over the submerged continental areas, and presenting dissimilar * It would seem, from Geikie's description of the Faroe Islands, that they may be a remnant of such connecting land, dating from the Cretaceous or Eocene period. alh^VJifciM a fc ITT ii»1 THE HISTORY OF THE NORTH ATLANTIC 17 conditions of sedimentation. It would seem also that, as Hicks has argued for Europe, and Logan and Hall for America, this Cambrian age was one of slow subsidence of the land previously elevated, accompanied with or caused by thick deposits of detritus along the borders of the subsiding shore, which was probably covered with the decomposing rock arising from long ages of subaerial waste. In the coal formation age its characteristic swampy flats stretched in some places far into the shallower parts of the ocean. ^ In the Permian, the great plicated mountain margins were fully developed on both sides of the Atlantic. In the Jurassic, the American continent probably extended farther to the sea than at present. In the Wealden age there was much land to the west and north of Great Britain, and Professor Bonney has directed attention to the evidence of the existence of this land as far back as the Trias, while Mr. Starkie Gardiner has insisted on connecting links to the southward, as evidenced by fossil plants. So late as the Post-glacial, or early human period, large tracts, now submerged, formed portions of the continents. On the other hand, the interior plains of America and Europe were often submerged. Such submergences are indicated by the great limestones of the Palaeozoic, by the chalk and its representative beds in the Cretaceous, by the Num- mulitic formation in the Eocene, and lastly, by the great Pleis- tocene submergence, one of the most remarkable of all, one in which nearly the whole northern hemisphere participated, and which was probably separated from the present time by only a few thousands of years.- These submergences and clc- * I have shown the evidence of tliis in the remnants of CaiboiiifeiDiis dibtricts once more extensive on the Atlantic coast of Nova Scotia and Cape Breton ("Acadian Geology "). ' The recent surveys of the Falls of Niagara coincide with a great many evidences to which I have elsewhere referred in proving that the I'leistoceiie submergence of America and Europe came to an end not more than ten ^r 1 7^ TIIK HISTORY OF THE NORTH ATLANTIC I i ii- . \ r vations were not always alike on the two sides of the Atlantic. The Salina period of the Silurian, for example, and the Ju'assic, show continental elevation in America not shared by Europe. The great subsidences of the Cretaceous and the Eocene were proportionally deeper and wider on the eastern continent, and this and the direction of the land being from north to south, cause more ancient forms of life to survive in America. These elevations and submergences of the plateaus alternated with the periods of mountain-making plication, which was going on at intervals, at the close of the Eozoic, at the beginning of the Cambrian, at the close of the Siluro-Cambrian, in the Permian, and in Europe and Western America in the Tertiary. The series of changes, however, affecting all these areas was of a highly complex character in detail.^ We may also note a fact which I have long ago insisted on,^ the regular pulsation of the continental areas, giving us alter- nations in each great system of deep-sea and shallow-water beds, so that the successive groups of formations may be di- vided into triplets of shallow-water, deep-water, and shallow- water strata, alternating in each period. This law of succession applies more particularly to the formations of the continental plateaus, rather than to those of the ocean margins, and it shows that, intervening between the great movements of plica- tion there were subsidences of those plateaus, or elevations of the sc"^ bottom, which allowed the waters to spread themselves over all the inland spaces between the great folded mountain ranges of the Atlantic borders. In referring to the ocean basins we should bear in mind that there are three of these in the northern hemisphere — the Arctic, the Pacliic, and the Atlantic. De Ranee has ably thousand years ago, and was itself not of very great duration. Thus in Pleistocene times the land must have been submerged and re-elevated in a very rapid manner. ' *' Acadian Geology." -.-■^ij^gSMCT .,=» -jLii,-.!. ^Jistc- THE HISTORY OF THE NORTH ATLANTIC 79 summed up the known facts as to Arctic geology in a series of articles in Nature^ from which it appears that this area pre- sents from without inwards a succession of older and newer formations from the Eozoic to the Tertiary, and that its extent must have been greater in former periods than at present, while it must have enjoyed a comparatively warm climate from the Cambrian to the Pleistocene period. The relations of its deposits and fossils are closer with those of the Atlantic than with those of the Pacific, as might be anticipated from its wider opening into the former. Blandford has recently remarked on the correspondence of the marginal deposits around the Pacific and Indian oceans,^ and Dr. Dawson informs me that this is equally marked in comparison with the west coast of America, but these marginal areas have not yet gained much on the ocean. In the North Atlantic, on the other hand, there is a wide belt of comparatively modern rocks on both sides, more especially toward the south and on the American side ; but while there appears to be a perfect correspondence on both sides of the Atlantic, and around the Pacific respectively, there .seems to be less parallelism between the dei)Osits and forms of life of the two oceans, as compared with each other, and less correspondence in forms of life, especially in modern times. Still, in the earlier geological ages, as might have been antici- pated from the imperfect development of the continents, the same forms of life characterise the whole ocean from Australia to Arctic America, and indicate a grand unity of Pacific and ^ Jouviu^l of Geological Society, May, 1886. Blandford's slatements re- specling the mechanical depcsits of the close of the Pala:ozoic in the Indian Ocean, whether these are glacial or not, would seem to show a correspond- ence with the Permian conglomerates ami earth movements of the Allan- tic area ; but since that time the Atlantic has enjoyed comparative repose. The Pacific seems to have reproduced the conditions of the Carboniferous in the Cretaceous age, and seems to have been less affected by the great changes of the Pleistocene. f^f^ b'o TIIK HISTORY OF TIIK NORTH ATI-ANTIC I Ailaniic life not equalled in later times/ and which speaks of true contemporaneity rather than of what has been termed homotaxis or mere likeness of orders. We may pause here for a moment to notice some of the effec::s of Atlantic growth on modern geography. It has given us rugged and broken shores, composed of old rocks in tlic north, and newer formations and softer features to- ward the south. It has given us marginal mountain ridges and internal plateaus on both sides of the sea. It has pro- duced certain curious and by no means accidental corre- spondences of the eastern and western sides. Thus the solid basis on which the British Islands stand may be compared with Newfoundland and Labrador, the English Channel with the Gulf of St. Lawrence, the Bay of Bieray with the Bay of Maine, Spain with the projection of the American land at Cape Hatteras, the Mediterranean with the Culf of Mexico. The special conditions of deposition and plication necessary to these results, and their bearing on the character and pro- ductions of the Atlantic basin, would require a volume for their detailed elucidation. Thus far our discussion has been limited almost entirely to physical causes and effects. If we now turn to the life history of the Atlantic, we are met at the threshold with the . (question of climate, not as a thing fixed and immutable, but as changing from age to age in harmony with geographical mutations, and producing long cosmic summers and winters of alternate warmth and refrigeration. AVe can scarcely doubt that the close connection of the Atlantic and Arctic oceans is one factor in those remarkable vicissitudes of climate experienced by the former, and in which the Pacific area has also shared in connection with the * Daintiee and Elheridge, " Queensland Geology, "y<;w;-«a/ Ceological Society, August, 1872 ; R. Elheridge, Junior, "Australian Fossils," Ivans. Phys. Soc, Edin., 1880. THE HISTORY OF THE NORTH ATLANTIC 8l 7 runs. Antarctic Sea. No geological facts are indeed at first sight more strange and ine.\i)licable than the changes of climate in the Atlantic area, even in comparatively modern periods. We know that in the early Tertiary temperate conditions reigned as far north as the middle of Clreenland, and that in the Pleisto- cene the Arctic cold advanced until an almost perennial winter prevailed half way to the equator. It is no wonder that nearly every cause available in the heavens and the earth has been invoked to account for these astounding facts. I shall, I trust, be excused if, neglecting most of these theoretical views, I venture to invite attention, in connection with this question, chiefly to the old Lyellian doctrine of the modificatio'x of climate by geographical changes. Let us, at least, consider how much these are able to account for. The ocean is a great equalizer of extremes of temperature. It does this by its great capacity for heat, and by its cooling and heating power when passing from the solid into the licpiid and gaseous slates, and the reverse. It also a( ts by its mobility, its currents serving to convey heat to great distanres, or to cool the air by the movement of cold icy waters. The land, on the other hand, cools or warms rapidly, and can transmit its influence to a distance only by the winds, and the influence so transmitted is rather in the nature of a disturbing than of an equalizing cause. It follows that any change in the distribution of land and water must affect climate, more espe- cially if it changes the character or course of the ocean currents. Turning to the Atlantic, in this connection we perceive that its present condition is peculiar and exceptional. On the one hand it is widely open to the Arctic Sea and the influence of its cold currents, and on the other it is supplied with a heating apparatus of enormous power to give a special elevation of temperature, more particularly to its eastern coasts. The great equatorial current running across from Africa is on its northern side embayed in the Gulf of Mexico, as in a great n \ !i 1 r'?! :ii r 82 THE HISTORY OF THE NORTH ATLANTIC cauldron, and pouring through the mouth of this in the Bahama channel, forms the gulf stream, which, widening out like a fan, forms a vast expanse of warm water, from which the pre- vailing westerly winds of the North Atlantic waft a constant supply of heated moist air to the western coasts of Europe, giving them a much more warm and uniform climate than that which prevails in similar latitude in Eastern America, where the cold Arctic currents hug the shore, and bring down ice from Baffin's Bay. Now all this might be differently arranged. \.e shall find that there were times, when the Isthmus of Panama being broken through, there was no Gulf Stream, and Norway and England were reduced to the conditions of (Ireenland and I-abrador, and when refrigeration was still further increased by subsidence of northern lands affording freer sweep to the Arctic currents. On the other hand, there were times when the Gulf of Mexico extended much farther north than at present, and formed an additional surface of warm water to heat all the interior of America, as well as the Atlantic. Geo- graphical changes of these kinds, have probably given us the glacial period in very recent times, and at an earlier era those warm climates which permitted temperate vegetation to flourish as far north as Greenland. These are, however, great topics, which must form the subject of other chapters. I am old enough to remember the sensation caused by the delightful revelations of Edward Eorbes respecting the zones of animal life in the sea, and the vast insight which they gave into the significance of the work on minute organisms pre- viously done by Ehrenberg, Lonsdale and Williamson, and into the meaning of fossil remains. A little later the sound- ings for the Atlantic cable revealed the chalky foraminiferal ooze of the abyssal ocean. Still more recently, the wealth of facts disclosed by the Challenger voyage, which naturalists have scarcely yet had time to digest, have opened up to us new worlds deep- THE HISTORY OF THE NORTH ATLANTIC S3 The bed of the deep Atlantic is covered, for the most part, by a mud or ooze, largely made up of the debris of foraniini- fera and other minute organisms mixed with fine clay. In the North Atlantic the Norwegian naturalists call tiiis the Biloculina mud. Farther south, the C/ia/Zciiji^cr naturalists j-peak of it as (llobigerina ooze. In point of fact it contains different species of foraminiferal shells, (ilobigcrina and Orbulina being in some localit.es dominant, and in others, other s[)ecies : and these changes r more apparent in the shallower portions of ihe ocean. On the other hand, there are means for dijfsen inating coarse material over parts of the ocean beds. There are, in the line of the Arctic current, on the American coast, great sand banks, and off the coast of Norway, sand constitutes a considerable part of the bottom material. Soundings and dredgins^s off Great Britain, and also off the American coast, have shown that fragmeiits of stone referable to Arctic lands are abundantly strewn over the bottom, along certain lines, and the Antarctic continent, otherwise almost unknown, makes its presence felt to the dredge by the abundant masses of crystalline rock drifted far from it to the north. These are not altogether new discoveries. I had inferred, many years ago, from stones taken up by the hooks of fishermen on the banks of Newfoundland, that rocky material from the north is dropped on these banks by the heavy ice which drifts over them every spring, that these are glaciated, and that after they fall to the bottom sand is drifted over them with sufficient velocity to polish the stones, and to erode the shelly coverings of Arctic animals attacher" to them.^ If, then, the Atlantic basin were upheaved into land, we should see beds of sand, gravel and boulders with clay flats and layers of marl and limestone. According to the Challenger- reports, in the Antarctic seas S. of 64° there is blue mud, with fragments of rock, in depths ^ "Notes on Post-Pliocine of Canada," 1872. 84 THE HISTORY OF THE NORTH ATLANTIC I ^\ >? t i it '■$ t of 1,200 to 2,000 fathoms. The stones, some of them glaci- ated, were granite, diorite, amphiboHte, mica schist, gneiss and quart/jt.. This deposit ceases and gives place to Globigerina oo/,e and red clay at 46° to 47° S., but even farther north there is sometimes as much as 49 percent, of crystalline sand. In the Labrador current a block of syenite, weighing 400 lbs., was taken up from 1,340 flithoms, and in the Arctic current, 100 miles from land, was a stony deposit, some stones being glaciated. Among these were smoky t^uartz, quartzite, lime- stone, dolomite, mica schist, and serpentine ; also particles of monoclinic and triclinic felspar, hornblende, augite, magnetite, mica and glauconite, the latter, no doubt, formed in the sea bottom, the others drifted from Eozoic and Palieozoic forma- tions to the north. ^ A remarkable fact in this connection is that the great depths of the sea are as impassable to the majority of marine animals as the land itself. According to Murray, while twelve of the Challenger-'' s dredgings, taken in depths greater than 2,000 fathoms, gave 9;- 'species, mostly new to science, a similar number of dredgings in shallower water near the land, give no less than 1,000 speckles. Hence arises another apparent para- dox relating to the distribution of organic beings. While at first, sight it might seem that the chances of wide distribution are exceptionally great for marine species, this is not so. Ex- cept in the case of those which enjoy a period of free locomo- tion when young, or are floating and pelagic, the deep ocean sets bounds to their migrations. On the other hand, the spores of cryptogamic plants may be carried for vast distances by the wind, and the growth of volcanic islands may effect connections which, though only temporary, may afford oppor- tunity for land animals and plants to pass over. With reference to the transmission of living beings across the Atlantic, we have before us the remarkable fact that from * Getterai Report, " Challenger''' Exprdition, Tin-: HISTORY of the north Atlantic 85 2,000 icross from the Cambrian age onwards there were, on the two sides of the ocean, many species of invertebrate animals which were either identical or so closely allied as to be possibly varietal forms, in- dicating probably the shallowness of the ocean in these periods. In like manner, the early plants of the Upper vSilurian, Devo- nian, and Carboniferous present many identical species ; but this identity is less marked in more modern times. Even in the latter, however, there arc remarkable connections between the floras of oceanic islands and the continents. Thus the Bermudas, altogether recent islands, have been stocked by the agency chiefly of the ocean currents and of birds, with nearly 150 species of continental plants ; and the facts col- lected by Helmsley as to the present facilities of transmission, along with the evidence afforded by older oceanic islands which have been receiving animal and vegetable colonists for longer periods, go far to show that, time being given, the sea actually affords facilities for the migration of the in- habitants of the land, comparable with those of continuous continents. In so far as plants are concerned, it is to be ol>served that the early forests were largely composed of cryptogamous plants, anf^ the spores of these in modern times have proved capable of transmission from great distances. In considering this, we cannot foil to conclude, that the union of simple cryp- togamous fructification with arboreal stems of high complexity, so well illustrated by Dr. Williamson, had a direct relation to the necessity for a rapid and wide distribution of these ancient trees. It seems alsocert^'in that some spores, as, for example, those of the Rhizocarps,^ a type of vegetation abundant in the PaUeozoic, and certain kinds of seeds, as those named Althoetesta and Pachytheca, were fitted for flotation. Further, the periods of Arctic warmth permitted the passage around ^ See paper by the author on Paljcozoic Rhizocarps, Chicago Traits., 1886. 86 THE HISTORY OF THE NORTH ATLANTIC I the northern belt of many temperate species of plants, just as now happens with the Arctic flora ; and when these were dis- placed by colder periods, they marched southward along both sides of the sea on the mountain chains. The same remark applies to northern forms of marine inver- tebrates, which arc much more widely distributed in longitude than those farther south. The late Mr. Gywn Jeffreys, in one of his latest communications on this subject, stated that 54 per cent, of the shallow-water mollusks of New England and Canada are also European, and of the deep-sea forms, 30 out of 35 ; these last, of course, enjoying greater facilities for migration than those which have to travel slowly along the shallows of the coast in order to cross the ocean and settle themselves on both sides. Many of these animals, like the common mussel and sand clam, are old settlers which came over in the Pleistocene period, or even earlier. Others, like the common periwinkle, seem to have been slowly extending them- selves in modern times, perhaps even by the agency of man. The older immigrants may possibly have taken advantage of lines of coast now submerged, or of warm periods, when they could creep round the Arctic shores. Mr. Herbert Carpenter and other naturalists employed on the ChaUeni:;er collections have made similar statements respecting other marine inverte- brates, as, for instance, the Echinoderms, of which the deep- sea crinoids present many common species, and my own collec- tions prove that many of the shallow-water forms are common. ])all and Whiteaves^ have shown that some mollusks and Echinoderms are common even to the Atlantic and Pacific coasts of North America ; a remarkable fact, testifying at once to the fixity of these species and to the manner in which they have been able to take advantage of geographical changes. Some of the species of whelks common to the Gulf of St. Lawrence and the Pacific are animals which have no special * Dall, Report on Alaska ; Whiieave;,, Trans. R, S, C. I [ |i . THE HISTORY OF THE NORTH ATLANTIC 87 locomotive powers, even when young, but they are northern forms not proceeding far south, so that they may have passed through the Arctic seas. In this connection it is well to re- mark that many species of animals have powers of locomotion in youth which they lose when adult, and that others may have special means of transit. I once found at Gaspe a specimen of the Pacific species of Coronula, or whale-barnacle, the C. regince of Darwin, attached to a whale taken in the Gulf of St. Lawrence, and which had possibly succeeded in making that passage around the north of America which so many navigators have essayed in vain.^ But it is to be remarked that while many plants and marine invertebrates are common to the two sides of the Atlantic, it is different with land animals, and especially vertebrates. I do not know that any palceozoic insects or land snails or millipedes of Europe and America are specifically identical, and of the numerous species of batrachians of the Carboniferous and reptiles of the Mesozoic, all seem to be distinct on the two sides. The same appears to be the case with the Tertiary mammals, until in the later stages of that great period we find such genera as the horse, the camel, and the elephant appear- ing on the two sides of the Atlantic ; but even then the species seem different, except in the case of a few northern forms. Some of the longer-lived mollusks of the Atlantic furnish suggestions which remarkably illustrate the biological aspect of these questions. Our familiar friend the oyster is one of these. The first-known oysters appear in the Carboniferous in Belgium and in the United States of America. In the Carboniferous and Permian they are few and small, and they do not culminate till the Cretaceous, in which there are no less than ninety-one so-called species in Amc-ica alone ; but some of the largest known species are found in the Eocene. The oyster, though * I am informed, however, tiiat the Coronula is found also in the Bis- cayan whales. r J 88 THE HISTORY OF THE NORTH ATLANTIC 'it. Ul ; ' ■ an inhabitant of shallow water, and very limitedly locomotive when young, has survived all the changes since the Carbon- iferous age, and has spread itself over the whole norther.' hemisphere,^ though a warm water rather than Arctic type. I have collected fossil oysters in the Cretaceous clays of the coulees of Western Canada, in the Lias shales of England, in the Eocene and the Cretaceous beds of the Alps, of Egypt, of the Red Sea coast, of Judea, and the heights of Lebanon. Everywhere and in all formations they present forms which are so variable and yet so similar that one might suppose all the so-called species to be mere varieties. Did the oyster originate separately on the two sides of the Adantic, or did it cross over so promptly that its appearance seems to be identical on the two sides ? Are all the oysters of a common ancestry, or did the causes, whatever they were, which introduced the oyster in the Carboniferous act over again in later periods ? Who can tell ? This is one of the cases where causation and develop- ment— the two scientific factors which constitute the basis of what is called evolution— cannot easily be isolated. I would recommend to those biologists who discuss these questions to devote themselves to the oyster. This familiar mollusk has successfully pursued its course, and has overcome all its enemies, from the flat-toothed selachians of the Carboniferous to the oyster dredges of the present day, has varied almost indefinitely, and yet has continued to be an oyster, unless, indeed, it may at certain portions of its career have temporarily assumed the guise of a Gryphcea or an Exogyra. The history of such an animal deserves to be traced with care, and much curious in- formation respecting it will be found in the report which I have cited in the note. But in these respects the oyster is merely an example of many forms. Similar considerations apply to all those Pliocene and Pleistocene rnoUusks which are found in the raised sea 1 White, J^e^ori U. S, Geo/. Sun'ey, 1882-83. THE HISTORY OF THE NORTH ATLANTIC 89 of bottoms of Norway and Scotland, on the top of Moel Tryfaen, in Wales, and at similar great heights on the hills of America, many of v.hich can be traced back to early Tert'ary *^^imes, and can be found to have extended themselves over all the seas of the northern hemisphere. They apply in like manner to the ferns, the conifers, and the broad-leaved trees, many of v\h'ch we can now trace without specific change to the Eocene and Cretaceous. Tiiey all show that the forms of living things are more stable than the lands and seas in which they live. If we were to adopt some of the modern ideas of evolution, we might cut the Gordian knot by supposing that, as like causes produce like effects, these types of life have originated more than once in geological time, and need not be genetically connected with each other. But while evolutionists repudiate such an appli- cation of their doctrine, however natural and rational, it w'ould seem that nature still more strongly repudiates it, and will not allow us to assume more than one origin for one species. Thus the great question of geographical distribution remains in all its force ; and, by still another of our geological paradoxes, mountains become ephemeral things in comparison with the delicate herbage which covers them, and seas are in their pre- sent extent but ot >csterday, when compared with the minute and feeble organisms that creep on their sands or swim in their waters. The question remains : Has the Atlantic achieved its des- tiny and finished its course, or are there other changes in store for it in the future ? The earth's crust is now thicker and stronger than ever before, and its great ribs of crushed and folded rock are more firm and rigid than in any previous period. The stupendous volcanic phenomena manifested in Alesozoic and early Tertiary times along the borders of the Atlantic have apparently died out. These facts are in so far guarantees of permanence. On the other hand, it is known that move- ments of elevation, along with local depression, are in progress TT 90 THE HISTORY OF THE NORTH ATLANTIC |! f ! / ' li. ^ ^^ l> in the Arctic regions, and a great weight of new sediment is being deposited along the borders of the Atlantic, especially on its western side ; and this is not improbably connected with the earthqr.ake shocks and slight movements of depression which have occurred in North America. It is possible that these slight and secular movements may go on uninterruptedly, or with occasional paroxysmal disturbances, until considerable changes are produced. It is possible, on the other hand, that after the long period ot quiescence which has elapsed, there may be a new settlement of the ocean bed, accompanied with foldings of the crust, es- pecially on the western side of the Atlantic, and possibly with renewed volcanic activity on its eastern margin. In either case, a long time relatively to our limited human chronology may intervene before the occurrence of any marked change. On the whole, the experience of the past would lead us to ex- pect movements and eruptive discharges in the Pacific rather than in the Atlantic area. It is therefore not unlikely that the Atlantic may remain undisturbed, unless secondarily and in- directly, until after the Pacific area shall have attained to a j eater degree of quiescence than at present. But this subject is one too much involved in uncertainty to warrant us in follow- ing it farther. In the meantime the Atlantic is to us a practically permanent ocean, varying only its tides, its currents, and its winds, which science has already reduced to definite laws, so that we can use if we cannot regulate them. It is ours to take advantage of this precious time of quietude, and to extend the blessings of science and of our Christian civilisation fr jm shore to shore, until there shall be no more sea, not in the sense of that final drying-up of old ocean to which some physicists look forward, but in the higher sense of its ceasing to be the emblem of un- rest and disturbance, and the cause of isolation. I must now close this chapter with a short statement of some THE HISTORY OF THE NORTH ATLANTIC 91 gene.al truths which I have had in view in directing attention to the geological development of the Atlantic. We cannot, I think, consider the topics to which I have referred with- out perceiving that the history of ocean and continent is an example of progressive design, quite as much as that of living beings. Nor can we fail to see that, while in some important directions we have penetrated the great secret of nature, in reference to the general plan and structure of the earth and its waters, and the changes through which they have passed, we have still very much to learn, and perhaps quite as much to unlearn, ana that the future holds out to us and to our suc- cessors higher, grander, and clearer conceptions than those to which we have yet attained. The vastness and the might of ocean and the manner in which it cherishes the feeblest and most fragile beings, alike speak to us of Him who holds it in the hollow of His hand, and gave to it of old its boundaries and its laws ; but its teaching ascends to a higher tone when we consider its origin and history, and the manner in which it has been made to build up continents and mountain-chains, and, at the same time, to nourish and sustain the teeming life of sea and land. References : — Presidential Address to the British Association for the Advancement of Science, Birmingham, 18S6. " Geology of Nova Scotia, New Brunswick, and Prince Edward Island." Fovntii Edition, London, 1S91. S. E. T I. } ' I I 1 11 II -t lit .1 ;: III ! . I THE DAWN OF LIFE. DEDICATED TO THE .MEMORY OF •SIR WILLIAM E. LO(;aN, The unwearied Explokek c,e tue Laiukxt.an Rocks, AND THE Founder OK THE Geological Survey or Canada. !''; < ni t -A PI i r; > I ) What are the Oidest Rocks, and where?— Conditions OF their Formation— Indications of Lifk— What its probable Nature ! t. ['IONS T ITS rr ii ' \ii it Nature-print of Eozoon, sho^-ing laminated, acervuline, and fragmental portions. This is printed from an electrotype taken from an etched slab of Eozoon, and not touched with a graver except to remedy some accidental flaws in the plate. The diagonal whitt line marks the course of a calcite vein. ■r* CHAPTER V. ental zoon, \vs in THE DAWN OF LIFE DO we know the first animal ? Can we name it, explain its structure, and state its relations to its successors ? Can we do this by inferencf: from the succeeding types of being ; and if so, do our anticipations agree with any actual reality disinterred from the earth's crust ? If we could do this , either by inference or actual discovery, how strange it would be to know that we had before us even the remains of the first creature that could feel or will, and could place itself in vital relation with the great powers of inanimate nature. If we believe in a Creator, we shall feel it a solemn thing to have access to the first creature into whii h He breathed the breath of life. If we hold that all things have been evolved from collision of dead forces, then the first molecules of matter which took upon themselves the responsibility of living, and, aiming at the enjoyment of happiness, subjected themselves to the dread alternatives of pain and mortality, must surely evoke from us that filial reverence which we owe to the authors of our own being ; if they do not involuntarily draw forth even a superstitious adoration. The veneration of the old Egv-.an for his sacred animals would be a comparatively reasonable idolatry, if we could imagine any of these animals to have been the first that emerged /rom the domain of dead matter, and the first link in a reproductive chain of being that produced all the population of the world. Independently of any such hypotheses, all students of nature must regard with surpassing 9^ ^!H^- 96 THE DAWN OF LIFE i f I i ;■ li« \ interest the first bright streaks of hght that break on the long reign of primeval night and death, and presage the busy day of teeming animal existence. No wonder, then, that geologists have long and earnestly groped in the rocky archives of the earth in search of some record of this patriarch of the animal kingdom. But after long and patient research there still remained a large residuum of the oldest rocks destitute of all traces of living beings, and designated by the hopeless name " Azoic," — the formations destitute of remains of life, the stony records of a lifeless world. So the matter remained till the Laurentian rocks of Canada, lying at the base of these old /./oic formations, afforded forms believed to be of organic origin. The dis- covery was hailed with enthusiasm by those who had been prepared by previous study to receive it. It was regarded with feeble and not very intelligent faith by many more, and was met with half-concealed or open scepticism by others. It pro- duced a copious crop of descriptive and controversial literature, but for the most part technical, and confined to scientific trans- actions and periodicals, read by very few except specialists. Thus, few even of geological and biological students have clear ideas of the real nature and mode of occurrence of these ancient organisms, if organisms they are, and of their relations to better known forms of life ; while the crudest and most in- accurate ideas have been current in lectures and popular books, and even in text-books. This state of things has long ceased to be desirable in the interests of science, since the settlement of the questions raised is in the highest degree important to the history of life. We cannot, it is true, affirm that Eozoon is in reality the long- sought prototype of animal existence ; but it was for us, at least until recently, the last organic foothold, on which we can poise ourselves, that we may look back into the abjss of the infi- nite past, and forward to the long and varied progress of life in 'M 1 THE DAWN OF LIFE 97 geological time. Now, however, we have announcements to be referred to in the sequel of other organisms discovered in the so-called Archcxan rocks ; and it is not improbable that these will rapidly increase. The discussion of its claims have also raised questions and introduced new points, certain, if properly entered into, to be fruitful of interesting and valuable thought, and to form a good introduction to the history of life in con- nection with geology. As we descend in depth and time into Lhe earth's crust, after passing through nearly all the vast senes of strata consti- tuting the monuments of geological history, we at length reach the Eozoic or Laurentian rocks,i deepest and oldest of all the formations known to the geologist, and more thoroughly altered or metamorphosed by heat and heated moisture than any others. These rocks, at one time known as Azoic, being sup- posed destitute of all remains of living things, but now more properly Eozoic, are those in which the first bright streaks of the dawn of life make their appearance. The name Laurentian, given originally to the Canadian development of these rocks by Sir William Logan, but now applied to them throughout the world, is derived from a range of hills lying north of the St. Lawrence valley, which the old French geographers named the Laurentides. In these hills the harder rocks of this old formation rise to considerable heights, and form the highlands separating the St. Lawrence valley from the great plain fronting on Hudson's Bay and the Arctic Sea. At first sight it may seem strange that rocks so ancient should anywhere appear at the surface, especially on the tops of hills ; but this is a necessary result of the mode of formation of our continents. The most ancient sediments deposited in the sea were those first elevated into land, and first altered and hardened. Upheaved in the folding of the earth's crust into high and rugged ridges, they have either re- * Otherwise named "Archaean." il 98 THE DAWN OF LIFE I Hi ' i. i (< i li I mained uncovered with newer sediments, or have had such as were deposited on them washed away ; and being of a hard and resisting nature, they have remained comparatively unworn when rocks much more modern have been swept off by denud- ing agencies.^ But the exposure of the old Laurentian skeleton of mother earth is not confined to the Laurentide Hills, though these have given the formation its name. The same ancient rocks appear in the Adirondack mountains of New York, and in the patches which at lower levels protrude from beneath the newer formations along the American coast from Newfoundland to Maryland. The older gneisses of Norway, Sweden, and the Hebrides, of Bavaria and Bohemia, of Egypt, Abyssinia and Arabia, belong to th*^ same age, and it is not unlikely that similar rocks in many other parts of the old continent will be found to be of as great antiquity. In no part of the world, however, are the Laurentian rocks more extensively distributed or better known than in Canada ; and to this as the grandest and most instructive development of them we may more especially devote our attention. The Laurentian rocks, associated with another series only a litde younger, the Huronian, form a great belt of broken and hilly country, extending from Labrador across the north of Canada to Lake Superior, and thence bending northward to the Arctic Sea. Everywhere on the lower St. Lawrence they appear as ranges of billowy rounded ridges on the north side of the river, and as viewed trom the water or the southern shore, especially when sunset deepens their tints to blue and violet, they present a grand and massive appearance, which, in the eye of the geologist, who knows that they have endured the battles and the storms of time longer than any other moun- ' This implies the permanence of continents in their main features, a doctrine the writer has maintained for thirty years, and which is discussed elsewhere. THE DAWN OF LIFE 99 tains, invests them with the dignity which their mere elevation would fail to give. (Fig. i.) In the isolated mass of the Adirondacks, south of the Canadian frontier, they rise to a still greater elevation, and form an imposing mountain group, almost equal in height to their somewhat more modern rivals, the White Mountains, which face them on the opposite side of Lake Champlain. The grandeur of the old Laurentian ranges is, however, best displayed where they have been cut across by the great trans- verse gorge of the Saguenay, and where the magnificent preci- pices, known as Capes Trinity and Eternity, look down from their elevation of 1,500 feet on the fiord, which at their feet is more than 100 fathoms deep. The name Eternity applied to such a mass is geologically scarcely a misnomer, for it dates back to the very dawn of geological time, and is of hoar antiquity in comparison with such upstart ranges as the Andes and the Alps. (See Frontisoiece.) On a nearer acquaintance, the Laurentian country appears as a broken and hilly upland and highland district, clad in its pristine state with magnificent forests, but affording few attrac- tions to the agriculturist, except in the valleys, which follow the lines of its softer beds, while it is a favourite region for the angler, the hunter, and the lumberman. Many of the Lauren- tian townships of Canada are, however, already extensively settled, and the traveller may pass through a succession of more or less cultivated valleys, bounded by rocks or wooded hills and crags, and diversified by running streams and roman- tic lakes and ponds, constituting a country always picturesque and often beautiful, and rearing a strong and hardy population. To the geologist it presents in the main immensely thick beds of gneiss, bedded diorite and quartzite, and similar crystalline rocks, contorted in the most remarkable manner, so that if they could be flattened out they would serve as a skin much too large for mother earth in her present state, so much has IH lOO THE DAWN OF LIFE S/ ;''ilPM ll.'.' S I, THE DAWN OF LIFE lOI she shrunk and wrinkled since those youthful days when the Laurentian rocks were her outer covering. I cannot describe such rocks, but their names, as given in the section. Fig. 2, will tell something to those who have any knowledge of the older crystalline^ materials of the earth's crust. To those who have not, I would advise a visit to some cliff on the lower St. Lawrence, or the Hebridean coasts, or the shore of Norwny, where the old hard crystalline and gnarled beds present their sharp edges to the ever raging sea, and show their endless alternations of various kinds and colours of strata, often diversified with veins and nests of crystalline minerals. He who has seen and studied such a section of Laurentian rock cannot forget it. The elaborate stratigraphical work of Sir William Logan has proved that these old crystalline rocks are bedded or stratified, and that they must have been deposited in succession by some process of aqueous action. They have, however, through geological ages of vast duration been subjected to pressure and chemical action, which have, as stated in a pre- vious chapter, much modified their struc- ture, while it is also certain that they must have differed originally from the sands, clays and other materials laid down in the sea in later times. w <: tyj CO 2 ^ k ii s ■** -^ ■!3 -^ \r 102 THE DAWN OF LIFE \ i"i i^r It is interesting to notice here that the Laurentian rocks thus interpreted show tiiat the oldest known portions of our continents were formed in the waters. They are oceanic sedi- ments deposited perhaps when there was no dry land, or very little, and that little unknown to us, except in so far as its ^3ris may have entered into the composition of the Lauren- tian rocks themselves. Thus the earliest condition of the earth known to the geologist is one in which old ocean was already dominant on its surface ; and any previous condition when the surface was heated, and the water constituted an abyss of vapours enveloping its surface, or any still earlier con- dition in which the earth was gaseous or vaporous, is a matter of mere inference, not of actual observation. The formless and void chaos is a deduction of chemical and physical prin- ciples, not a fact observed by the geologist. Still we know, from the great dykes and masses of igneous or molten rock which traverse the Laurentian beds, that even at that early period there were deep-seated fires beneath the crust ; and it is quite possible that volcanic agencies then manifested them- selves, not only with quite as great intensity, but also in the same manner, as at subsequent times. It is thus not unlikely that much of the land undergoing waste in the earlier Lauren- tian time was of the same nature with recent volcanic ejections, and that it formed groups of islands in an otherwise boundless ocean. However this may be, the distribution and extent of these pre-Laurentian lands is, and probably ever must be, unknown to us ; for it was only after the Laurentian rocks had been deposited, and after the shrinkage and deformation of the earth's crust in subsequent times had bent and contorted them, that the foundations of the continents were laid. The rude sketch map of America given in Fig. 3 will show this, and will also show that the old Laurentian mountains mark out the future form of the American continent. ri; THE DAWN OF LIFE 103 Some subsequent writers have, it is true, treated with dis- behef Logan's great discoveries ; but no competent geologist who has traced the regularly beddf 1 limestones and other rocks of his original fields of inves .gation could continue to doubt. On this subject I may quote from my friend Dr. Bonney, one of the most judicious of the builders who under- take hypothetically to lay the foundation stones of the earth's Fig. 3. — The Laurcntian Nucleus of the American Cuntincnt, cftcr I ana. crust for our enlightenment in these later days. In an address delivered at the Bath meeting of the British Association he says : — " The first deposits on the solidified crust of the earth would obviously be igneous. As water condensed from the atmo- sphere on the cooling surface, aqueous waste or condensation would begin, and stratified deposits in the ocean would become nr 104 THE DAWN OF LIFE : « i possible in addition to detrital volcanic material. But at that time the crust itself, and even later stratified deposits would often be kept for a considerable period at a high temperature. Thus, not only rocks of igneous origin (including volcanic ashes) would predominate in the lowest foundation stones, but also secondary changes would occur more readily, and even the sediments or precipitates might be greatly modified. As time went on, true sediments would predominate over volcanic materials, and these would be less and less affected by chemical changes, and would more and more retain their original char- acter. Thus we should expect that as we retraced the earth's course through * the corridor of time ' we should arrive at rocks which, though crystalline in structure, were evidently in great part sedimentary in origin, and should behind them find rocks of more coarsely crystalline texture and more dubious character, which, however, probably were in part of a like origin, and should at last reach coarsely crystalline rocks, in which, while occasional sediments would be possible, the majority were originally igneous, though modified at a very early period of their history, '"'"his corresponds with what we find in nature, when we apply, cautiously and tentatively, the principles of interpretation which guide us in stratigraphical geology." ^ This expresses very well the general result of the patient stratigraphical and chemical labours of Logan and Sterry Hunt, as applied to the vast areas of old crystalline stratified rocks in Canada, and which I have had abundant opportunities to verify on the ground. Under the undoubted Cambrian beds of Canada lies the Huronian, a formation largely of hardened sands, clays and gravels, now formirg sandstones, slates, and conglomerates, but with great beds of igneous or volcanic rock, and hardened and altered ash beds. Under » "The Foundation Stones of the Earth's Crust," 1888. The extract is slightly condensed. THE DAWN OF LIFE 105 this, in the upper portion of the Laurentian, we have regularly bedded rocks, quartzitcs, limestones, and quartzose, and gra- phitic and ferruginous gneisses, evidently altered aqueous sediments ; but intermixed with other rocks, as diorites and hornblendic gneisses, which are plainly of different origin. Lastly, on the bottom of all, we have nothing but coarse crystalline gneiss, representing perhaps the earliest crust of a cooling globe. Broadly, and without entering into details or theoretical views as to the precise causes of formation and alteration of these rocks, this is the structure of the Archccan or Eozoic system in Canada ; and it corresponds with that of the basement or foundation stones of our continents in eveiy country that I have been able to visit, or of which I have trustworthy accounts. In the lower or fundamental gneiss, and in the igneous beds which succeed it, we need not look for any indications of living beings ; but so soon as the sea began to deposit sand, mud, limestone, iron ore, carbon, there would be nothing to exclude the presence of some forms of marine life ; while, as land must have already existed, there would be a possibility of life on it. This, therefore, we may begin to look for so soon as we ascend to those beds of the Laurentian in which lime- stone, iron ore, and quartzite appear ; and it is precisely at this point in the Laurentian of Canada that indications of life are supposed to have been found. Certain it is that if we cannot find some sign of life in the Laurentian or Huronian, we shall have to face as the beginnings of life the swarms of marine creatures that appear all over the globe at once, in the early Cambrian age. Is it likely, then, that such rocks should atTord any traces of living beings, even if any such existed when they were formed? Geologists who had traced organic remains back to the lowest Cambrian might hope for such remains, even in the Lauren- tian ; but they long looked in vain for their actual discovery. S. E, 8 m n f ii Fig. 2. Fig. Fig. I. Small si'ECIMEN ok Eozoon, weathered out, natural size, from a photograph. Fig. 2. Canal System of Eozoon injected with serpentine (magni- fied). Fig. 3. Very eine Canals and Tuhuli fdled with Dolomite (magni- fied). (From Micio-photographs.) ■■ (\ 1 Hi y I If THE DAWN OF LIFE 113 with the exception of my friend, Professor Ramsay." In 1863 the general Report of the Geological Survey, summing up its Fig. 5. — Weathered Specimen of Eozoon from the Calumet. (Collected by Mr. McMullen.) Fig. 6. — Cross Section of the Specimen represented in Fig. 8. The dark parts are the lamina; of calcareous matter converging to the outer surface. r 114 THE DAWN OF LIFE i> t u[ » >. I u jl I ? »:■ < I work to that time, was published, under the name of the " Geology of Canada," and in this, at page 49, will be found two figures of one of the Calumet specimens, here reproduced, and which, though unaccompanied with any specific name or technical description, were referred to as probably Laurentian fossils. (Figs. 5 and 6.) About this time Dr. Hunt happened to mention to me, in connection with a paper on the mineralization of fossils which he was preparing, that he proposed to notice the mode of })rescrvation of certain fossil woods and other things with which I was familiar, and that he would show me the paper in proof, in order that I might give him any suggestions that occurred to me. On reading it, I observed, among other things, that he alluded to the supposed Laurentian fossils, under the impression that the organic part was represented by the serpentine or loganite, and that the calcareous matter was the filling of the chambers. I took exception to this, stating that though in the slices I had examined no structure was apparent, still my impression was that the calcareous matter was the fossil, and the serpentine or loganite the filling. He said — " In that case, would it not be well to re-examine the specimens, and try to discover which view is correct ? " He mentioned, at the same time, that Sir William had recently shown him some new and beautiful specimens collected by Mr. Lowe, one of the explorers on the staff of the Survey, from a third locality, at Grenville, on the Ottawa. It was supposed that these might throw further light on the subject ; and accordingly Dr. Hunt suggested to Sir William to have additional slices of these new specimens made by Mr. Weston, of the Survey, whose skill as a preparer of these and other fossils has often done good service to science. A few days thereafter some slices were sent to me, and were at once put under the microscope. I was delighted to find in one of the first specimens examined a beautiful group of tubuli penetrating THE DAWN OF LIFE 115 one of the calcite layers. Here was evidence, not only that the calcite layers represented the true skeleton of the fossil, but also of its affinities with the foraminifcra, whose tubulated supplemental skeleton, as described and figured by Dr. Car- penter, and represented in specimens in my collection, pre- sented by him, was apparently of the same type with that preserved in the canals of these ancient fossils. Fig. 7 is an accurate representation of the group of canals first detected by me. ^:.^. ^■^ •^ '■■(\.\ Fig. 7. — Group of Canals in the Supolemental Skeleton of Eozoon. Taken from the specimen in which they were first recognised. Magnified. (Camera tracing by Mr. H. S. Smith.) On showing the structures discovered to Sir ^\'illiam Logan, he entered into the matter with enthusiasm, and had a great number of slices, as well as decalcified specimens, prepared, which were placed in my hands for examination. Feeling that the discovery was most important, but that it would be met with determined scepticism by a great many geologists, I was not content with examining the typical speci- mens of Eozoon, but had slices prepared of every variety of ii6 THE DAWN OF LIFE Laurentian limestone, of altered limestones from the Primordial and Silurian, and of serpentine marbles of all the varieties furnished by our collections. They were examined with ordi- nary and polarized light, and with every variety of illumination. They were also examined as decalcified specimens, after the carbonate of lime had been removed by acids. An extensive series of notes and camera tracings were made of all the appearances observed ; and of some of the more important structures beautiful drawings were executed by the late Mr. H. S. Smith, the then palceontological draughtsman of the Survey. The result of the whole investigation was a firm con- viction that the structure was organic and foraminiferal, and that it could be distinguished from any merely mineral or crystalline forms occurring in these or other limestones. At this stage of the matter, and after exhibiting to Sir William all the characteristic appearances, in comparison with such concretionary, dendritic and crystalline structures as most resembled them, and also with the structure of recent and fossil Foraminifera, I suggested that the further prosecution of the matter should be handed over to Mr. Billings, as paleontologist of the Survey. I was engaged in other re- searches, not connected with the Survey or with this particular department, and I knew that no little labour must be devoted to the work and to its publication, and that some controversy might be expected. Mr. Billings, however, with his character- istic caution and modesty, declined. His hands were full of other work. He had not given any special attention to the microscopic appearances of Foraminifera or of mineral sub- stances. It was finally arranged that I should prepare a de scription of the fossil, which Sir William would take to London, along with the more important specimens, and a detailed list stating all the structures observed in each. Sir William was to submit the manuscript and specimens to Dr. Carpenter, or, failing him, to Prof. T. Rupert Jones, in the hope that these I ■' I V THE DAWN OF LIFE 117 eminent authorities would confirm my conclusions, and bring forward new facts v' " h I might have overlooked or been ignorant of. Sir William saw both gentlemen, who gave their testimony in favour of the organic and foraminiferal character of the specimens ; and Dr. Carpenter, in particular, gave much attention to the subject, and worked out more in detail many of the finer structures, besides contributing valuable suggestions as to the probable affinities of the supposed fossil. Dr. Carpenter thus contributed in a very important manner to the perfecting of the investigations begun in Canada, and on him fell the greater part of their illustration and defence,* in so far as Great Britain is concerned. The immediate result was a composite paper in the Pro- ceedings of the Geological Society, by Sir W. E. Logan, L"»r. Car- penter, Dr. Hunt, and myself, in which the geology, palaeonto- logy and mineralogy of Eozoon Canadr»<;e and its containing rocks were first given to the world.^ It cannot be wondered at that when geologists and palaeontologists were thus required to believe in the existence of organic remains in rocks regarded as altogether Azoic and hopelessly barren of fossils, and to carry back the dawn of life as far before those Primordial rocks, which were supposed to contain its first traces, as these are before the middle period of the earth's life history, some hesita- tion should be felt. Further, the accurate appreciation of the evidence for such a fossil as Eozoon required an amount of knowledge of minerals, of the more humble types of animals, and of the conditions of mineralization of organic remains, pos- sessed by few even of professional geologists. Thus Eozoon has met with some scepticism and not a little opposition, — though the latter has been weaker than we might have expected when ^ In Quarterly Jonrttal of Geological Society, vol. xxii. ; Froc. Royal Society, vol. xv. ; Intellectual Observer, 1S65. Annals and Magazine of Natural History, 1874 ; and other papers and notices. ^ Journal Ceohoical Society, February, 1865. .t"^ ii8 THE DAWN OF LIFE f we consider the startling character of the facts adduced, and has mostly come from men imperfectly informed. But what is Eozoon, if really of animal origin? The shortest answer to this question is, that this ancient fossil is supposed to be the skeleton of a creature belonging to that simple and humbly organized group of animals which are known by the name Protozoa. If we take as a familiar example of these the gelatinous and microscopic creature found in stagnant ponds, and known as the Ania'ba ^ (Fig. 8), it will form a convenient starting-point. Viewed under a low power, it a[)pcars as a little patch of jelly, irregular in form, and constantly changing its aspect as it moves, by the extension of parts of its body into finger-like processes or pseudopods which serve as extempore limbs. When moving on the surface of a slip of glass under the microscope, it seems, as it were, to flow along rather than creep, and its body appears to be of a semi-fluid consistency. It may be taken as an example of the least complex forms of animal life known to us, and is often spoken of by naturalists as if it were merely a little particle of living and scarcely organ- ized jelly or protoplasm. When minutely examined, Avever, it will not be found so simple as it at first sight appears. Its outer layer is clear and transparent, and more dense than the inner mass, which seems granular. It has at one end a curious vesicle which can be seen gradually to expand and become filled with a clear drop of liquid, and then suddenly to contract and expel the contained fluid through a series of pores in the adjacent part of the outer wall. This is the so-called pulsating vesicle, and is an organ both of circulation and excretion. In another part of the body may be seen the nucleus, which is a little cell capable, at certain times, of producing by its division new individuals. Food, when taken in through the wall of the body, forms little pellets, which become surrounded by a ^ The alternating animal, alluding to its change of form. fin' THE DAWN OF LIFE 119 digestive liquid exuded from the enclosing mass into rounded cavities or extemporised stomachs. Minute granules are seen to circulate in the gelatinous interior, and may be substitutes for blood-cells, and the outer layer of the body is capable of protrusion in any direction into long processes, which are very mobile, and used for locomotion and prehension. Further, this creature, though destitute of most of the parts which we are at.-istomed to regard as proper to animals, seems to exer- cise volition, and to show the same appetites and passions with animals of higher type. I have watched one of these animal- gan- ever, Its the lOUS come itract the ating In is a i^ision )f the by a Fig. 8. Amoeba. F/G. 9. Actinophrys. From original sketches. cules endeavouring to swallow a one-celled plant as long as its own body ; evidently hungry and eager to devour the tempting morsel, it stretched itself to its full extent, trying to envelope the object of its desire. It failed again and again ; but renewed the attempt, until at length, convinced of its hopelessness, it flung itself away as if in disappointment, and made off in search of something more manageable. With the Amoeba are found other types of equally simple Protozoa, but somewhat differently S, K. 9 i I 120 THE DAWN OF LIFE i W \1 1 >l ^!i 1 l!i organized. One of these, Actinophr-ys (Fig. 9), lias the body globular and unchanging in form, the outer wall of greater thick- ness ; the [)ulsating vesicle like a blister on the surface, and the j)seudopods long and thread-like. Its habits arc similar to those of the Amcxiba, and I introduce it to show the variations of form and structure possible even among the.se simple creatures. J The Amoeba and Actinophrys are fresh-water animals, and are destitute of any shell or covering. But in the sea there ex- ist swarms of similar creatures, equally simple in organization, but gifted with the power of secreting around their soft bodies beautiful little shells or crusts of carbonate of lime, having one orifice, and often in addition multitudes of microscopic pores through which the soft gelatinous matter can ooze, and form outside finger-like or thread-like extensions for collecting food. In some cases the shell consists of a single cavity only, but in most, after one cell is completed, others are added, forming a series of cells or chambers communicating with each other, and often arranged spirally or otherwise in most beautiful and symmetrical forms. vSome of these creatures, usually named Foraminifera, are locomotive, others sessile and attached. Most of them are microscopic, but some grow by multiplication of chambers till they are a quarter of an inch or more in breadth. The original skeleton or primary cell wall of most of these creatures is seen under the miscrosco]:)e to be perforated with innumerable pores, and is extremely thin. When, however, owing to the increased size of the shell, or other wants of the creature, it is necessary to give strength, this is done by add- ing new portions of carbonate of lime to the outside, and to these Ur. Carpenter has given the appropriate name of " sup- plemental skeleton " ; and this, when covered by new growths, becomes what he has termed an " intermediate skeleton." The supplemen«-al skeleton is also traversed by tubes, but these are THE DAWN 01- LIFE 121 often of larger size than the j)orcs of the cell-wall, and of greater length, and branched in a complicated manner. Thus there are microscopic characters by which these curious shells ran be distinguished from those of other marine animals ; and by applying these characters we learn that multitudes of creatures of this type have existed in former periods of the world's history, and that their shells, accumulated in the bottom of the sea, constitute large portions of many limestones. The manner in which such accumulation takes place we learn from what is now going on in the ocean, more especially from the result of the recent deep-sea dredging expeditions. The Foraminifera are vastly numerous, both near the surfiice and at the bottom of the sea, and multi[)ly rapidly ; and as suc- cessive generations die, their shells accumulate on the ocean bed, or are swept by currents into banks, and thus, in process of time, constitute thick beds of white chalky material, which may eventually be hardened into limestone. This process is now depositing a great thickness of white ooze in the bottom of the ocean ; and in times past it has produced such vast thicknesses of calcareous matter as the chalk and nummulitic limestone of Europe and the orbitoidal limestone of America. The chalk which alone attains a maximum thickness of i,ooo feet, and, according to Lyell, can be traced across Europe for i,ioo geographical miles, may be said to be entirely -composed of shells of Foraminifera imbedded in a paste of smaller calcareous bodies the Coccoliths, which are probably products of marine vegetable life, if not of some animal organism still simpler than the Foraminifera. Lastly, while we have in such modern forms as the masses of Polytrema attached to corals, and the Loftusa of the Eocene and the carboniferous, large fossil foraminiferal species, there is some reason to believe that in the earlier geo- logical ages there existed much larger animals of this grade than are found in our present seas ; and that these, always iJ ■ t 122 THE DAWN OF LIFE i \ t ' 1 ' 1 li K sessile on the bottom, grew by the addition of successive chambers, in the same manner with the smaller species.^ Let us, then, examine the structure of Eozoon, taking a typical specimen, as we find it in '.he limestone of Grenville or Petite Nation. In such specimens the skeleton of the animal is represented by a white crystalline marble, the cavities of the cells by green serpentine, the mode of whose introduction we shall have to consider in the sequel. The lowest layer of ser- pentine represents the first gelatinous coat of animal matter which grew upon the bottom, and which, if we could have seen it before any shell was formed upon its surface, must have resembled a minute patch of living slime. On this primary layer grew a delicate calcareous shell, perforated by innumer- able minute tubuH, and resting on the slimy matter of the animal, though supported also by some perpendicular plates or septa. Upon this again was built up, in order to strengthen it, a thickening or supplemental skeleton, more dense, and desti- tute of fine tubuli, but traversed by branching canals, through which the soft gelatinous matter could pass for the nourish- ment of the skeleton itself, and the extension of pseudopods be- yond it. (Figs. 11,12.) So was formed the first layer of Eozoon, which probably was at its beginning only of very small dimen- sions. On this the process of growth of successi^-e layers of animal sarcode and of calcareous skeleton was repeated again and again, till in some cases even a hundred or more layers were formed (nature-print, Chap. VI.) As the process went on, however, the vitality of the organism became exhausted, prob- ably by the deficient nourishmimt of the central and lower layers making greater and greater demands on those above, and so the succeeding layers became thinner, an J less sup- plemental skeleton was developed. Finally, toward the top, the regular arrangement in layers was abandoned, and the cells 1 I refer to some of the Stromatoporce of the Silurian and the Cryptozoon of the Cambrian. See note appended to this chapter. THE DAWN OF LIFE 123 became a mass of rounded chambers, irregularly piled up in what Dr. Carpenter has termed an " acervu'.ine " manner, and with very thin walls unprotected by supplemental skeleton. Then the growth was arrested, and possibly these upper layers gave off reproductive germs, fitted to float or swim away and to establish new colonies. We may have such reproductive germs in certain curious globular bodies, like loose cells, found m connection with Eozoon in many of the Laurentian lime- ' '' ■ , '; I! li I <^.'?ii'^A'i^V mmi li T ^;'*=-;°--^J'""l^' Foraminiferal forms from iIk Laurentian of Lom; Lake. Highly magnified, (a) Single cell, showing aibulated wall. (/>, n I ortions of same more highly magnified. (,/) Serpentine cast of a snnilar chamber, decalcified, and showing casts of tubuli. stones.i At St. Pierre, on the Ottawa, these bodies occur on the surface of layers of the limestone in vast numbers, as if they had been growing separately on the bottom, or had been drifted over it by currents. They may have served as repro- > It would be interesting to compare these bodies Nvith the forms re- cent ly found by Barrois and Cayeux in the - Azoic " quart^ite of Brittany, which should certainly now be called Eozoic. If J n m i 1 ■ I M m I n 124 THE DAWN OF LIFE ductive buds or germs to establish new colonies of the species. Such was the general mode of growth of Eozoon, and we may now consider more in detail som-^' questions as to its gigantic size, its precise mode of nutrition, the arrangement of its parts, its relations to more modern forms, and the effects of its growth in the Laurentian seas. With respect to the size of Eozoon, this was rivalled by some succeeding animals of the same humble type in later geo- logical ages ; and, as a whole, foraminiferal animals have been diminishing in size in the lapse of geological time. This is indeed a fact of so frequent occurrence that it may almost be regarded as a law of the introduction of new forms of life, that they assume in their early history gigantic dimensions, and are afterwards continued by less magnificent species. The relations of this to external conditions, in the case of higher animals, are often complex and difficult to understand ; but in organisms so low as Eozoon and its allies, they lie more on the surface. Such creatures may be regarded as the simplest and most ready media for the conversion of vegetable matter into animal tissues, and their functions are almost entirely limited tc chose of nutrition. Hence it is likely that they will be able to appear in the most gigantic forms under .such conditions as afford them the greatest amount of pabulum for the nourishment of their soft parts and for their skeletons. There is reason to believe, for example, that the occurrence, both in the chalk and the deep-sea mud, of immense quanti- ties of the minute bodies known as Coccoliths along with Foraminifera, is not accidental. The Coccoliths appear to be grains of calcareous matter formed in minute plants adapted to a deep-sea habitat ; and these, along with the vegetable and animal (f3n's constantly being derived from the death of the living things at the surface, afford the material both of sarcode and shell. Now if the Laurentian graphite represents an exuberance of vegetable growth in those old seas propor- THE DAWN OF LIFE 12; tionate to the great supplies of carbonic acid in the atmosphere and in the waters, and if the Eozoic ocean was even better suppHed with salts of lime than those Silurian seas whose vast limestones bear testimony to their richness in such material, we can easily imagine that the conditions may have been more favourable to a creature like Eozoon than those of any other period of geological time. Growing, as Eozoon did, on the floor of the ocean, and covering wide patches with more or less irregular masses, it must have thrown up from its whole surface its pseudopods to seize whatever floating particles of food the waters carried over it. There is also reason y.o believe, from the outline of certain specimens, that it often grew upward in conical or club- shaped forms, and that the broader patches were penetrated by large pits or oscula, admitting the sea-water deeply into the substance of the masses. In this way its growth might be rapid and continuous ; but it does not seem to have possessed the power of growing indefinitely by new and living layers covering those that had died, in the manner of some corals. Its life seems to have had a definite termination, and when that vi-as reached, an entirely new colony had to be commenced. In this it had more affinity with the Foraminifera, as we now know them, than with the corals, though practically it had the same power with the coral polyps of accumulating limestone m the sea bottom— a power indeed still possessed by its fora- miniferal successors. In the case of coral limestones we know that a large proportion of these consist not of continuous reefs, but of fragments of coral mixed with other calcareo.i" organisms, spread usually by waves and currents in continuous beds over the sea bottom. In like manner we find in the limestones containing Eozoon, layers of fragmental matter which show in places the characteristic structures, and which evidently represent the ifrfir/s swept from the Eozoic masses and reefs by the action of the waves. It is with this frag- i I 1. I ' 126 THE DAWN OF LIFE ). \ I? « •: AU I mental matter that the small rounded organisms already re- , ferred to most frecjuently occur ; and while they may be distinct animals, they may also be the fry of Eozoon, or small l)ortions of its acervuline upper surface floated off in a living state, and possibly capable of living independently and of founding new colonies. It is only by a somewhat wild poetical licence that Eozoon has been represented as a " kind of enormous composite animal stretching from the shores of Labrador to Lake Superior, and thence northward and southward to an unknown distance, and forming masses 1,500 feet in depth." We may, it is true, readily believe in the composite nature of masses of Eozoon, and we see in the corals evidence of the great size to which composite animals of a higher grade can attain. Li the case of Eozoon we must imagine an ocean floor more uniform and level than that now existing. On this the organism would establish itself in spots and patches. These might finally be- come confluent over large areas, just as massive corals do. As individual masses attained maturity and died, their pores would be filled up with limestone or silicious deposits, and thus could form a solid basis for new generations, and in this way limestone to an indefinite extent might be produced. Eurther, wherever such masses were high enough to be attacked by the breakers, or where portions of the sea bottom were elevated, the more fragile parts of the surface would be broken up and scattered widely in beds of fragments over the bottom of the sea, while here and there beds of mud or sand, or of volcanic debris would be deposited over the living or dead organic mass, and would form the layers of gneiss and other schistose rocks interstratified with the Laurentian limestone. In this way, in short, Eozoon would perform a function combining that which corals and Eoraminifera perform in the modern seas ; forming both reef limestones and exten- sive chalky beds, and probably living both in the shallow and ^ THE DAWN OF LIFE 127 the deeper parts of the ocean. If in connection with this we consider the rapidity with which the soft, simple, and ahnost structureless sarcode of these Protozoa can be built up, and the probabili':y that they were more abundantly supplied with food, both for nourishing their soft parts and skeletons, than any similar creatures in later times, we can readily understand the great volume and extent of the Laurcntian limestones which they aided in producing. I say aided in producing, because I would not care to commit myself to the doctrine hat the Laurentian limestones are wholly of this origin, here may have been other limestone builders than Eo/.oon, Fir,. II. — Section of ti Nummulite, from Eocene Limestone of Syria. Showing chambers, tubiili, and canals. Compare this and Fig. 12 with VVj:_. 7 and Nature-print of Kozoon. and there may have been limestones formed by plants like the modern Nullipores, or by merely mineral deposition. Its relations to modern animals of its type have been very clearly defined by Dr. Carpenter. In the structure of its proper wall and its fine parallel perforations, it resembles the Numniulitcs and their allies ; and the organism may therefor-e be regarded as an aberrant member of the Nummulinc group, which affords some of the largest and most widely distributed of the fossil Foraminifera. This resemblance may be seen in Fig. II. To the Nummulites it also conforms in its tendency to form a supplemental or intermediate skeleton with canals. 'i E l« ^!l ^' ' m 1^; !' 128 THE DAWN OF LIFE though the canals themselves in the arrangement more nearly resemble Calcarina, which is represented in I'ig. 12. In its superposition of many layers, and in its tendency to a heaped up or acervuline irregular growth it resembles Poly! .na and Tinoporus^ forms of a different group in so far as shell-struc- ture is concerned. It may thus be regarded as a composite type, combining peculiarities now observed in two groups, or it may be regarded as representing one of these in another scries. At the time when Dr. Carpenter stated these Fig, 12. — Portion of shell of Calcarina. Mngni'lod, after Carpenter, (rt) Cells. (/') Original cell wnll with tubiUi. {c) Supplementary skeleton Avilh canals. affinities, it might be objected that Foraminifera of these families are in the main found in the modern and Tertiary periods. Dr. Carpenter has since shown that the curious oval Foraminifer called Fusuliiia, found in the coal formation, is allied to both Nummulites and Rotalines ; and Mr. Brady has discovered a true Nummulite in the Lower Carboniferous of Belgium. I have myself found small Foraminifera in the Silurian and Cambro-Silurian of Canada, This group being ■> THE DAWN OF LIKE 129 hese tiary oval now brought down to the Palaeozoic, we may hope to trace it to the Primordial, and thus to bn'ng it still nearer to Eozoon in time. ' Though Eozoon was probably not the only animal of the Laurentian seas, yet it was in all likelihood the most con- spicuous and important as a collector of calcareous matter, filling the same place afterwards occupied by the reef-building corals. Though probably less efficient than these as a con- structor of solid limestones, from its less permanent and con- tinuous growth, it formed wide floors and patches on the sea bottom, and when these were broken up, vast quantities of limestone were formed from their debris. It must also be borne in mind that Eozoon was not everywhere infiltrated with ser- pentine or other silicious minerals ; quantities of its substance were merely filled with carbonate of lime, resembling the chamber wall so closely that it is nearly impossible to make out the difference, and thus is likely to pass altogether unobserved by collectors, and to baffle even the microscopist. Although, therefore, the layers which contain well characterised Eozoon are few and far between, there is reason to believe that in the composition of the limestones of the Eaurentian it bore no small part, and as these limestones are some of them several hundred feet in thickness, and extend over vast areas, Eozoon may be supposed to have been as efficient a world-builder as the Stromatopora; of the Silurian and Devonian, the Globi- gerinai and their allies in the chalk, or the Nummulites and Miliolites in the Eocene. It is a remarkable illustration of the constancy of natural causes and of the persistence of animal types, that these humble Protozoans, which began to secrete calcareous matter in the Eaurentian period, have been continuing their work in the ocean through all the geological ages, and are still busy in accumulating those chalky muds with which recent dredging operations in the deep sea have made us so familiar. (See Note appended.) All this seems sufficiently reasonable, more especially since I' Ml lit 130 THE DAWN OF LIFE 4 i > I. f > 1 li t no mineralogist has yet succeeded in giving a feasible inor- ganic explanation of the combination of canals, laminte, tubu- lation and varied mineral character existing in Eozoon. But then comes the strange fact of its apparent isolation with- out companions in highly crystalline rocks, and with appa- rently no immediate successors. This has staggered many, and it certainly, if taken thus baldly, seems in some degree improbable. Recent discoveries, however, are removing this reproach from Eozoon. The Laurentian rocks have yielded other varieties, or perhaps species of the genus, those which I have described as variety Acervulina, and variety Minor, and still another form, more like a Stromatopora, which I have provisionally named II. latior^ from the breadth and uniformity of its plates. 1 There are also in the Taurentian limestone cylindrical bodies apparently originally tubular, and with the sides showing radiating markings in the manner of corals, or of the curious Cambrian Archoeocyathus. Matthew, a most careful observer, has found in the Laurentian limestone of New Brunswick certain laminated bodies of cylindrical form, constituting great reefs in the limestone, and in the slates linear flat objects resembling Alga^ or Graptolites, and spicular structures resembling those of sponges.'- }]ritton has also de- scribed from the Laurentian limestone of New Jersey certain ribbon-like objects of graphite which he regards as vegetable, and names AnJucopJiyio)i Ncivbcrryii? Should these objects prove to be organic, Eozoon will no longer be alone. Besides this the peculiar bodies named Cryptozoum by Hall, and which are intermediate in structure between Eozoon and Loftusia, have now been found as low as the Lower Cambrian.'^ Barrois * Notes on Specimens of Eozoon, " Memoirs of Peter Rei.lpatli Museum,"' 1888. 2 BuL Nat. Hist. Nlw Brunsxvick, No. IX., 1890. ^ Aiiiia/s N'.Y. Aiadeiiiy of Science, 1888. ^ Walcott, Lower Cambrian, 1892. THE DAWN OF LTFE 131 -1 ;ts iia. has also recently announced the discovery of forms which he regards as akin to the modern Radiolaria, creatures of a little higher grade than the Foraminifcra, in the " Archaean " rocks of Brittany.^ Thus Eozoon is no longer isolated, but has companions of the same great age with itself. The progress of discovery is also daily carrying the life of the Cambrian to lower beds, and thus nearer to the Laurcntian. It is not un- likely that in a few years a pre-Cambrian fauna will force itself on the attention of the most sceptical geologists. References: — "Life's Dawn on Earth," London, 1S75. (Now out of print.) ".Specimens of Eozoon Canadense in tlie Peter Redpath Museum, Montreal," 1888. (This memoir contains reference to pre- vious papers.) * Nalural Scieine, Oct., 1S92. Appended Notes. 1. Stroiiiatopora. — It has been usual of late to regard these as allies of the modern Millepores and Hydrcetinias ; but careful study of large series of specimens has convinced me that some species, notably the Stromato- ccrium of the Cambro-Silurian and the cryptozotivi of the Cambrian, cannot be so referred. I hope to establish this in the future, if time permit. 2. Modern Foraminifera. — The discovery by Brady and Lister of reproductive chamberlets at the margin of the modern orbitolites, tends to connect this with Eozoon. The gigantic foraminiferal species discovered by Agassiz at the Gallipagos, has points of affinity with Eozoon ; and its arenaceous nature does not affect this, as we know sandy species in this group closely allied to others that are calcareous. •OlS 111, ir r \ M % WHAT A/AV BE LEARNED FROM EOZOON. DKDICATED TO THE ME.\rORY OF DR. WILLIAM B. CARPENTER, Who, among nrs many Skrvtcks to SciENcE. DEVOTKD MUCH TiME AND LABOUR TO THE InVESTIOATIoN OK Eozoon, and ry his Knowledge of Foraminifera AND UNRIVALLED POVVER OF UNRAVELLING DIFFICULT Structures DID much TO Render it Intelligible, ■r ii^ t I ' t.l >'^i |.-^ il The Microscope in Geology — Contributions of the Study of Eozoon to our Kno\vledge of the Mode OF Preservation of Fossils — Its Teaching Rela- tively TO the Origin of Life and the Laws of its Introduction and Progress it'i THE ►lODE lELA- F ITS S. E. lO ^iP-UHBaai r' htu il. u § Si'EClMKX OK EozooN Canadense (Dawson), showing Genera Form and Osculiform Tubes. (Reproduced from riiotograph.) .r CHAPTER VI. miAT MAY BE LEARNED FROM EOZOON. -pHE »ieroscope has long been a recognised and valued table-^'M v\ a\ \ ! Internal Structure of Fossil Vege- a student . KdilXl It ^ atuai^^^r ^/t" " : p™ :«;!: 7 -'" ""'^ "°^^^^ ^- n'»' -^ ^v;,i ;u^e«evei,,oe,ea::rra:.^;rcrn:r— i:: o n,,croscop,c scrutiny, not as a mere specialist in tl,at"Ce of observation, or with the parade of methods and d M i , °t customary, but with the view of obtaining valuable la'ts beTr- ^ Edinburgh, i8jj^ »33 ^il I ffl Ml i |;^ 136 WHAT MAY BE LEARNED FROM EOZOON m IV. '1 ing on any investigation I might have in hand. It was this habit which induced my old friend, Sir "William Logan, in 1858 and subsequent years to ask my aid in the study of the forms believed or suspected to he organic, which had been discovered in the course of his surveys of the Laurentian rocks. In one respect this was unfortunate. It occupied much time, inter- fered to some extent with other researches, led to unpleasant controversies. But these evils were more than compensated by the insight which the study gave into the fact of the persistence of organic structures in highly crystalline rocks, and to the modes of ascertaining and profiting by these obscure remains, while it has guided and stimulated enquiry and thought as to the origin and history of life. These benefits entitle the re- searches and discussions on Eozoon to be regarded as marking a salient point in the history of geological discovery, and it is to these principally that I would attract attention in the pre- sent chapter. Perhaps nothing excites more sceptic sm as to the animal nature of Eozoon than the prejudice existing among geologists that no organism can be preserved in rocks so highly crystalline as those of the Laurentian series. I call this a prejudice, be- cause any one who makes the microscopic structure of rocks and fossils a special study, soon learns that fossils and the rocks containing them may undergo the most remarkable and complete mechanical and chemical changes without losing their minute structure, and that limestones, if once fossilife^'ous, are hardly ever so much altered as to lose all traces of the organisms which they contained, while it is a most common occurrence to find highly crystalline rocks of this kind abound- ing in fossils preserved as to their minute structur' Let us, however, look at the precise conditions under which this takes place. When calcareous fossils of irregular surface and porous or cellular texture, such as Eozoon may have been, or corals were •f^J WHAT MAY BE LEARNED FROM EOZOON 137 and are, become imbedded in clay, marl, or other soft sedi- ment, they can be washed out and recovered in a condition similar to that of recent specimens, except that their pores or cells, if open, may be filled with the material of the matrix, or if not so open that they can be thus filled, they may be more or less incrusted with mineral deposits introduced by water percolating the mass, or may even be completely filled up in this way. But if such fossils are contained in hard rocks, they usually fail, when these are broken, to show their external sur- faces, and, breaking across with the containing rock, they ex- hibit their internal structure merely, — and this more or less distinctly, according to the manner in which their cells or cavities have been filled with mineral matter. Here the microscope becomes of essential service, especially when the structures are minute. A fragment of fossil v\^ood which to the naked eye is nothing but a dark stone, or a coral which is merely a piece of grey or coloured marble, or a specimen of common crystalline limestone made up originally of coral frag- ments, presents, when sliced and magnified, the most perfect and beautiful structure. In such cases it will be found that ordinarily the original substance of the fossil remains in a more or less altered state. Wood may be represc ated by dark lines of coaly matter, or coral by its white or transparent calcareous lamince ; while the material which has been introduced, and which fills the cavities, may so differ in colour, transparency, or crystallization, as to act differently on light, and so reveal the original structure. These fillings are very curious. Sometimes they are mere earthy or muddy matter which has been washed into the cavities. Sometimes they are transparent and crystal- line. Often they are stained with oxide of iron or coaly materials. They may consist of carbonate of lime, silica or silicates, sulphate of baryta, oxides of iron, carbonate of iron, iron pyrite, or sulphides of copper or lead, all of which are common materials. They are sometimes so complicated that \m\ 133 WHAT MAY 15E LEARNED FROM EOZOON ;(,*'• ' n J I have seen even the minute cells of woody structures, each with several bands of differently coloured materials deposited in succession, like the coats of an onyx agate. A further stage of mineralisation occurs when the substance of the organism is altogether removed and replaced by foreign matter, either little by little, or by being entirely dissolved or decomposed, leaving a cavity to be filled by infiltration. In this state are some silicified woods, and those corals which have been not filled with but replaced by silica, and can thus sometimes be obtained entire and perfect by the solution in an acid of the containing limestone, or by its removal in weathering. In this state are the beautiful silicified corals ob- tained from the corniferous limestone of Lake Frie, which are so perfectly replaced by flinty matter that when weathered out of the limestone, or treated with acid till the latter is removed, we find the coral as perfect as when recent. It may be well to present to the eye these different stages of fossilization. I have attempted to do this in Fig. 13, taking a tabulate coral of the genus Favosites for an example, and supposing the material employed to be calcite and silica. Precisely the same illustra- tion would apply to a piece of wood, except that the cell wall would be carbonaceous matter instead of carbonate of lime. In this figure the dotted parts represent carbonate of lime, the diagonally shaded parts silica or a silicate. Thus we have in the natural state the walls of carbonate of lime and the cavities empty (a). When fossilized the cavities may be merely filled with carbonate of lime, or they may be filled with silica (/;, (■) ; or the walls themselves may be replaced by silica, and the cavities may remain filled with carbonate of lime (d) ; or both the walls and cavities may be represented by or filled with silica or silicates (c). The ordinary specimens of Eozoon are supposed to be in the third of these stages, though some exist in the second, and I have reason to believe that some have reached to the fifth. I have not met with any in the f • ■ ■- ^^^^ WHAT MAY DE LEARNED FROM E07.00N '39 fourth stage, though this is not uncommon in Silurian and Devonian fossils. I have further to remark that the reason why wood and the cells of corals so readily become silicified is that the organic .natter which they contain, becoming oxidized in decay, produces carbon dioxide, which, by its affinity for alkalies, can decompose soluble silicates and thus throw down their silica in an insoluble state. Thus a fragment of decay- ing wood imbedded in a deposit holding water and alkaline silicates almost necessarily becomes silicified. It is also to be remarked that the ordinary specimens of Eozoon have actually not attained to the extreme degree of mineralization seen in some much more recent silicified woods and corals, inasmuch a \'[- ill ; in I ( '-^-^1 i! t P •Mli |7,.t \J/ V''t yp '^»^'* '•///// ^T'Jfk l-'u;. 13. — Diagram sliowinq different States of Fossilization of a cell of a Tulnilate Coral, {a) Natural condition — w.-ilis coicitc, cell eniiity. i.^) Walls calcite, cell filled with the same, (r) Walls calcite, cell filled with silica or silicate, (c/) Walls silicified, cell filled with calcite. {e) Walls silicified, cell filled with silica or silicate. as the portion believed to have been the original calcareous test has not usually been silicified, but still remains in the state of calcium carbonate. With regard, then, to the calcareous organisms with which we have now more especially to do, when these are embedded in pure limestone and filled with the same, so that the whole rock, fossils and cavities, is one in composition, and when meta- morphic action has caused the whole to become crystalline, and has perhaps removed the remains of carbonaceous matter, it may be very difficult to detect any traces of structure. But / 140 WHAT MAY BE LEARNED FROM EOZOON 1 r i I; even in this case careful management of light may reveal some indications. In many instances, however, even where the limestones have become perfectly crystalline, and the cleavage planes cut freely across the fossils, these exhibit their forms and minute structures in great perfection. This is the case in many of the Lower Silurian limestones of Canada, as I have elsewhere shown. ^ The grey crystalline Trenton limestone of Montreal, used as a building stone, is an excellent illustration. To the naked eye it is a grey marble composed of cleavable crystals ; but when examined in thin slices, it shows its or- ganic fragments in the greatest beauty, and all their minute parts are perfectly marked out by delicate carbonaceous lines. The only exception in this limestone is in the case of the crinoids, in which the cellular structure is filled with trans- parent calc-spar, perfectly identical with the original solid matter, so that they ai)pear solid and homogeneous, but there are examples in which even the minute meshes of these become apparent. The specimen represented in Fig. 14 is a mass of Corals, Polyzoa, and Crinoids, and shows these under a low power, as represented in the figure. The specimen in Fig. 15 shows the Laurentian Eozoon in a similar state of preservation. It is from a sketch by Dr. Carpenter, and exhibits the delicate canals partly filled with calcite or dolomite, as clear and colour- less as that of the shell itself, and distinguishable only by careful management of the light. In the case of recent and fossil Foraminifers, these very frequently have their chambers filled solid with calcareous matter, and as Dr. Carpenter well remarks, even well preserved Tertiary Nummulites in this state often fail greatly in showing their structures, though in the same condition they occasionally show these in great perfection. Among the finest I have seen are specimens from the Mount of Olives, and Dr. Carpenter ^ Canadian Naturalist^ 1859: "Microscopic Structure of Canadian Limestones." i «D WHAT MAY BE LEARNED FROM EOZOON 141 mentions as equally good those of the London clay at Brackle- sham. But in no condition do modem J'braminifera, or those of the Tertiary and Mesozoic rocks appear in greater perfection than when filled with the hydrous silicate of iron and potash \V'"^['y, \:'"/^^^li^- Fig, 14. — Slice of Crystalline Lower Silurian Lime.stune ; showing Crinoids, Bryozoa, and Corals in fragments. ^:\}i-S^.^-'ik:^^^~^'s-^J^^'^=i^'CjZy^^^~ ''' /\ Fig. 15. — \Yalls of Eozoon penetrated with Canals. The unshaded portions filled with Calcite. (After Carpenter.) called glauconite or green earth, a substance now forming in some parts of the ocean, and which gives, by tli*^ abundance of its little bottle-green concretions the name of " greensand " to formations of the Cretaceous age both in Europe aiid America. 142 WHAT MAY I5K LEARNED EKOM EO/.OON ill- Inii I V' 1 I In some beds of greensand every grain seems to have been moulded into the interior of a microscopic shell, and has re- tained its form after the frail envelope has been removed. In some cases the glauconite has not only filled the chambers but has penetrated the fine tubulation, and when the shell is removed, either naturally or by the action of an acid, the silicious fillings of the interior of the tubes project in minute needles or bundles of threads of marvellous delicacy from the surface of the cast. It is in the warmer seas, and especially in the bed of the Egean and of the Gulf Stream, that such specimens are now most usually found.' If we ask why this mineral glauconite should be associated with foraminiferal shells, the answer is that they are both products of one kind of locality. The same sea bottoms in which Foraminifera most abound are also those in which the chemical conditions for the formation of glauconite exist. Hence, no doubt, the association of this mineral with the great foraminiferal forma- tion of the chalk. It is indeed by no means unlikely that the selection by these creatures of the pure carbonate of lime from the sea water or its minute plants, may be the means of setting free the silica, iron, and potash, in a state suitable for dieir combination. Similar silicates are found associated with marine limestones, as far back as the Cambro-Silurian age ; and Dr. Sterry Hunt, than whom no one can be a better authority on chemical geology, has argued on chemical grounds that the occurrence of serpentine with the remains of Eozoon is an association of the same character. However this may be, the infiltration of the pores of Eozoon with serpentine and other silicates has evidently been one main means of its preservation. When so infiltrated no meta- morphism short of the complete fusion of the containing rock ^ Beautiful specimens of Nummulites preserved in this way, from the Eocene of Kumpfen in Bavaria, have been communicated to me through the kindness of Dr. Otto Ilahn. n WHAT MAY I!K LEARN KU KKOM EOZOON 143 ith ta- Ick he could obliterate the minutest points of structure ; and that such fusion has not occurred, the preservation in the Laurentian rocks of the most delicate lamination of the beds shows con- clusively ; while, as already stated, it can be shown that the alteration which has occurred might have taken place at a temperature far short of that necessary to fuse limestone. Thus has it happened that these most ancient fossils hnve been handed down to our time in a state of preservation com- parable, as Dr. Carpenter states, to that of the best preserved fossil Foraminifera from the more recent formations that have come under his observation in the course of all his long ex- perience. Let us now look more minutely at the nature of the typical specimens of Eozoon as originally observed and described, and then turn to those preserved in other ways, or more or less de- stroyed or defaced. Taking a polished specimen from Petite Nation, we find the shell re})resented by white limestone, and the chambers by light green serpentine. By acting on the surface with a dilute acid we etch out the calcareous part, leaving a cast in serpentine of the cavities originally occupied by the soft animal substance, and when this is done in polished slices, these may be made to print their own characters on l)aper, as has actually been done in tlv:" i)late prefixed, which is an electrotype from an etched specimen, and shows both the laminated and acervuline parts of the fossil. If the pro- cess of decalcification has been carefully executed, we find in the excavated spaces delicate ramifying processes of opacjue serpentine or transparent dolomite, which were originally im- bedded in the calcareous substance, and which are often of extreme fineness and complexity.^ (Figs. 18, 19.) These are casts of the canals which traversed the shell when still inhabited by the animal, and have subsequently been filled with mineral * Very fine specimens can be produced by polishing thin slices, and then etching them slightly witli a very weak acid. (Plate prefixed.) >^ ■U , '^ I'i ■X 11 i-it 144 WHAT MAY IJE LEARNED FROM EOZOON matter. In evidence of this we sometimes find in a single canal an outer tubular layer of serpentine and an inner filling of dolomite, just as vessels of fossil plants are sometimes filled with successive coats of different materials. In some well preserved si)ecimens we find the original cell wall represented hy a delicate white film, which under the microscope shows minute needle-like parallel processes representing its still finer tubuli. It is evident that to have filled these tubuli, the ser- pentine must have been introduced in a state of actual solution, and must have carried with it no foreign impurities. Conse- quently we find that in the chambers themselves the serpentine is pure ; and if we examine it under polarized light, we see that it i)resents a singularly curdled or irregularly laminated a])pear- ance, as if it had an imperfectly crystalline structure, and had l)een deposited in irregular laminre, beginning at the sides of the chambers, and filling them toward the middle, and had afterward been cracked by shrinkage, and the cracks filled with a second deposit of serpentine.^ Now, serpentine is a hydrous silicate of magnesia, and all that we need to suppose is that in the waters of the Laurentian sea magnesia was present instead of iron, alumina or potash, and we can understand that the Laurentian fossil has been petrified by infiltration with ser- pentine, as more modern Foraminifera have been with glaucon- ite, which, though it does not contain magnesia, often has a considerable percentage of alumina. Further, in specimens of Fozoon from Burgess, the filling mineral is loganite, a com- pound of silica, alumina, magnesia and iron with water, while in other specimens the filling mineral is pyroxene. In like ^ The same structures may be well seen in thin slices polished, to be viewed as transparent objects. I may, however, explain that if these are made roughly, and heated in the process, they may often show only mineral structures and cleavage planes, whereas, if polished with great care and slowly, and afterwards cleaned with an acid, the} may show the canals in great perfection. WHAT MAY BE LEARNED FROM EOZOON 145 manner, in certain Silurian limestones from New Brunswick and Wale:>, in which the delicate microscopic pores of the skeletons of stalked starfishes or crinoids have been filled with mineral deposits, so that when decalcified these are most beau- tifully represented by their casts, Dr. Hunt has proved the filling mineral to be^ intermediate between serpentine and glauconite. We have, therefore, ample warrant for adhering to his con- ■ ' .a:. Ito be pe are only care iv the a,--:;;.".,".; 'j.!jE;jF^-..- >^^c....<.i {;.ii;'i; : ::'^^ ••' '»?""*■ \ "rfl-'-i l'.~,%;i-: ■ f.NS?r-.^.;;.u4ii'.::, _,, ?.■■■••. ^P^.'" '-■-•! ".•?;• "=3-''.'..\ \; ■. s. <-i.:.f \ V i : , -t ■( ■•• ■ . ■■_ « ' • .'•■-M Fig. 16. — ^Joint of a Crinoid, having its Pores injected with a Hydrous Silicate. Upper Silurian Limestone, Pole Hill, New Brunswick. Magni- fied 25 diameters. elusion that the Laurentian serpentine was deposited under conditions similar to those of the modern greensand. Indeed, independently of Eozoon, it is impossible that any geologist who has studied the manner in which this mineral is associated with the Laurentian limestones could believe it to have been ^ Silicate of alumina, iron, magnesia, and potash. •' \ »t - 146 WHAT MAY liE LEARNED FROM EOZOON formed in any other way. Nor need we be astonished at the fineness of the infiUration by whieh these minute tubes, perhaps ,yi,,o of an inch in diameter, are filled with mineral matter. The micro geologist well knows how, in more modern deposits, the finest pores of fossils are filled, and that mineral matter in solution can penetrate the smallest openings that the micro- scope can detect. Wherever the fluids of the living body can penetrate, there also mineral substances can be carried, and Fig. 17.— Shell from a Silurian Limestone, Wnles ; its cavity filled with Hydrous Silicate. Magnified 25 diameters. this natural injection, effected under great pressure and with the advantage of ample time, can surpass any of the feats of the anatomical manipulator. Fig. 16 represents a microscopic joint of a Crinoid from the Upper Silurian of New Brunswick, injected with the hydrous silicate already referred to, and Fig. 17 shows a microscopic chambered or spiral shell, from a \\'elsh Silurian limestone, with its cavities filled with a similar substance. Taking the specimens preserved by serpentine as typical, we now turn to certain other and, in some respects, less character- )) __JVnAT^MAYJ^^^UaRN^ KKO.M EOXOON ,47 !hff.'r"'T'"' "■'''''' •"' "^■verthdcss very h.strucrivr At lime and ma-nesi-i 'I'Nn /^ '^^?"'-' f " anhydrous silicate of seen part of a chamber or group of canals filled with Fig. i8.-Casts of Canals of E ozoon in Serpentine, clecalcified and hi-Mily magnified, '^ ^ vx^v v^~ C- Vi--^ F'f l9.-Ca„aUofKozoo„. ILVLly .Mag„if,«|. more remarkable as pyroxene is n,os. uLlly found , an t gred,ent of .gneous rocks ; bu. Dr. Hunt has shown tl,a.n /"' Laurent,an hn.estones, and also in veins traversing ^ ! P.'il Mo 111'' T^ mmmmm 148 WHAT MAY BE LEARNED FROM EOZOON I ' i r-L if; ■■' i li/ ,1; Ltn i ■id I {!' occurs under conditions which imply its deposition from water, either cold or warm. Giinibel remarks on this : — " Hunt, in a very ingenious manner, compares this formation and deposition of serpentine, pyroxene, and loganite, with tliat of glauconite, whose formation has gone on uninterruptedly from the Silurian to the Tertiary period, and is even now taking place in the depths of the sea ; it being well known that Ehrenberg and others have already shown that many of the grains of glauconite are casts of the interior of foraminiferal shells. In the light of this comparison, the notion that the serpentine and such-like minerals of the primitive limestones h ive been formed, in a similar manner, in the chambers of Eozoic Foraminifera, loses any traces of improbability which it might at first seem to possess." In many parts of the skeleton of Eozoon, and even in the best infiltrated serpentine specimens, there are portions of the cell wall and canal system which have been filled with cal- careous spar or with dolomite, so similar to the skeleton that it can be detected only under the most favourable lights and with great care (Fig. 15, supra). It is further to be remarked that in all the specimens of true Eozoon, as well as in many other calcareous fossils preserved in ancient rocks, the cal- careous matter, even when its minute structures are not pre- served, or are obscured, presents a minutely granular or cuidled appearance, arising, no doubt, from the original presence of organic matter, and not recognised in purely inorganic calcite. Other specimens of fragmental Eozoon from the Petite Nation localities have their canals filled with dolomite, which prcbably penetrated them after they were broken up and im- bedded in the rock. I have ascertained, with respect to these fragments of Eozoon, that they occur abundantly in certain layers of the Laurentian limestone, beds of some thickness being in j;reat part made up of them, and coarse and fine frag- -^- w 150 WHAT MAY BE LEARNED FROM EOZOON been victimized, by having under their consideration only specimens in which the actual characters had been too much defaced to be discernible. No mistake can be greater than to suppose that any and every specimen of Laurentian limestone must contain Eozoon. More especially have I hitherto failed to detect traces of it in those carbonaceous or graphitic lime- stones which are so very abundant in the Laurentian country. Perhaps where vegetable matter was very plentiful Eozoon did not thrive, or, on the other hand, the growth of Eozoon may have diminished the quantity of vegetable matter. It is also to be observed that much compression and distortion have oc- curred in the beds of Laurentian limestone and their contained fossils, and also that ths specimens are often broken by faults. some of which are so small as to api)ear only on microscopic examination, and to shift the plates of the fossil just as if they were beds of rock. This, though it sometimes produces puzzling appearances, is an evidence that the fossils were hard and brittle when this faulting took place, and is consequently an additional proof of their extraneous origin. In some speci- mens it would seem that the lower and older part of the fossil had been wholly converted into serpentine or pyroxene, or had so nearly experienced this change that only small parts of the calcareous wall can be recognised. These portions correspond with fossil woods altogether silicified, not only by the filling of the cells, but also by the conversion of the walls into silica. I have specimens which manifestly show the transition from the ordinary condition of filling with serpentine to one in which the cell-walls are represented obscurely by one shade of tiiis mineral and the cavities by another. In general, however, it will be gathered from the above explanations that the specimens of Eozoon fall short in thoroughness of mineralization of some fossils in much more modern rocks. I have specimens of ancient sponges whose si)icular skeletons, originally silicious, have been replaced by pyrite or bisulphide of iron, and of i\! WHAT MAY r>E LEARNKD FROM EOZOOX 151 I Tertiary fossil woods retaining perfectly their most minute struc- tures, yet entirely replaced by silica, so that not a particle of the original wood remains. The above considerations as to mode of preservation of Eozoon concur with those in the previous chapter in showing its oceanic character, if really a fossil ; but the ocean of the Eozoic period may not have been so deep as at present, and its waters were probably warm and well stocked with mineral matters derived from the newly formed land, or from hot springs in its own bottom. On this point the interesting in- vestigations of Dr. Hunt with reference to the chemical con- ditions of the Silurian seas allow us to suppose that the Lau- rentian ocean may have been much more richly stored, more especially with salts of lime and magnesia, than that of subse- quent times. Hence the conditions of warmth, light, and nutri- ment required by such gigantic Protozoans would all be present, and hence, also, no doubt, some of the peculiarities of their mineralization. I desire by the above statement of facts to show, on the one hand, that the study of Eozoon, regarded as probably an ancient form of marine life, aids us in understanding other ancient fossils, and their manner of preservation; and on the other hand, that those who deny the organic origin of Eozoon place us in the position of being unable, in any rational manner, to account for these forms, so characteristic of the Laurentian limestones, and set at naught the fair conclusions deducible from the mode of preservation of fossils in the later formations. The evidence of organic origin is perhaps not conclusive, and in the present state of knowledge it is certain to be m.et with much scepticism, uiore especially by certain classes of specialists, whose grasp of knowledge is not sufficiently wide to cover, on the one hand, fossilization and metamorphism, and on the other, to under- stand the lower forms of life. It may, however, be sufficient to (jualify us in turning our thoughts for a few moments to con- I \ :^ ti m w 152 WHAT I\IAY BE LEARNED FROM EOZOON siderations suggested by the probable origin of animal life in the seas of the Laurentian period. Looking down from the elevation of our physiological and mental superiority, it is (;Jifficult to realize the exact conditions in which life exists in creatures so simple as the Protozoa. There may perhaps be higher intelligences, that find it equally difficult to realize how life and reason can manifest themselves in such poor houses of clay as those we inhabit. But placing ourselves near to these creatures, and entering, as it were, into sympathy with them, we can understand something of their powers and feelings. In the first place it is plain that they can vigorously, if roughly, exercise those mechanical, chemical, and vegetative powers of life which are characteristic of the animal. They can seize, swallow, digest, and assimilate food ; and, employing its albuminous parts in nourishing their tissues, can burn away the rest in processes akin to our respi- ration, or reject it from their system. Like us, they can sub- sist only on food which the plant has previously produced ; for in this world, from the beginning of time, the plant has been the only organism which could use the solar light and heat as forces to enable it to turn the dead elements of matter into living, growing tissues, and into organic compounds capable of nourishing the animal. Like us, the Protozoa ex- pend the food which they have assimilated in the production of animal force, and in doing so cause it to be oxidized, or burnt away, and resolved again into dead matter. It is true that we have much more complicated apparatus for performing these functions, but it does not follow that these give us much real superiority, except relatively to the more difficult condi- tions of our existence. The gourmand who enjoys his dinner may have no more pleasure in the act than the Am. ba which swallows a Diatom ; and for all that the man knows of the subsequent processes to which the food is subjected, his in- terior might be a mass of jelly, with extemporised vacuoles, WHAT MAY BE LEARNED FROM EOZOON 153 inds ex- tion or true ling iich ndi- iner lich the i ti- les, like that of his humble fellow-animal. The clay is after all the same, and there may be as much difficulty in the making of a simple organism with varied powers, as a more complex frame for doing higher work. In order that we may feel, a complicated apparatus of nerves and brain cells has to be constructed and set to work ; but the Protozoon, without any distinct brain, is all brain, and its sensation is simply direct. Thus vision in these creatures is probably performed in a rough way by any part of their transparent bodies, and taste and smell are no doubt in the same case. Whether they have any perception of sound as distinct from the mere vibrations ascertained by touch, we do not know. Here, also, we are not far removed above the Pro- tozoa, especially those of us to whom touch, seeing and hear- ing are direct acts, wit lout any thought or knowledge of the apparatus employed. ^Ve might, so far, as well be Amcebas. As we rise higher we meet with more differences. Yet it is evident that our gelatinous fellow being can feel pain, dread danger, desire possessions, enjoy pleasure, and in a direct un- conscious way entertain many of the appetites and passions that affect ourselves. The wonder is that with so little of organization it can do so much. Yet, perhaps, lite can mani- fest itself in a broader and more intense way where there is little organization, and a highly strung and complex organism is not so much a necessary condition of a higher life as a mere means of better adapting it to its present surroundings. A similar lesson is taught by the complexity of their skeletons. We speak in a crude, unscientific way of these animals accumulating calcareous matter, and building up reefs of limestone. We must, however, bear in mind that they are as dependent on their food for the materials of their skeletons as we are, and that their crusts grow in the interior of the sarcode just as our bones do within our bodies. The provision even for nourishing the interior of the skeleton by k * I I 154 WHAT MAY J}E LEARNED FROM EOZOON tubuli and canals is in principle similar to that involved in the canals, cells, and canalicules of bone. 'I'he Amceba, of course, knows neither more nor less of this than the average English- man. It is altogether a matter of unconscious growth. The process in the Protozoa strikes some minds, however, as the more wonderful of the two. It is, says an eminent modern physiologist, a matter of " profound significance " that this '"particle of jelly [the sarcode of a Foraminifer] is capable of guiding physical forces in such a manner as to give rise to these exquisite and almost mathematically arranged structures." Respecting the structures themselves there is no exaggeration in this. No arch or dome framed by human skill is more perfect in beauty or in the realization of mechanical ideas than the tests of some Foraminifera, and none is so complete and wonderful in its internal structure. The particle of jelly, how- ever, is a figurj of speech. The body of the humblest Foram- inifer is much more than this. It is an organism with divers parts, and it is endowed with the mysterious forces of life which in it guide the physical forces, just as they do in building up phosphate of lime in our bones, or indeed, just as the will of the architect does in building a palace. The profound signi- ficance which this has, reaches beyond the domain of the physical and vital, even to the spiritual. It clings to all our conceptions of living things : "quite as much, for example, to the evolution of an animal with all its parts from a one-celled germ, as to the connection of brain cells with the manifesta- tions of intelligence." Viewed in this way, we may share with the author of the sentence I have quoted his feeling of venera- tion in the presence of this great wonder of animal life, " burn- ing, and not consumed," nay, building up, and that in many and beautiful forms. We may realize it most of all in the presence of the organism which was perhaps the first to mani- fest on our planet these marvellous powers. We must, how- ever, here also, beware of that credulity which makes too many I WHAT MAY HE LEARNED FROM JiOZOON 155 thinkers limit their conceptions altogether to physical force in matters of this kind. The merely materialistic physiologist is really in no better position than the savage who (luails before the thunderstorm, or rejoices in the solar warmth, and seeing no force or })ower beyond, fancies himself in the immediate presence of his (lod. In Eozoon we must discern not only a mass of jelly but a being endowed with that higher vital force which surpasses vegetable life, and also physical and chemical forces ; and in this animal energy we must see an emanation from a Will higher than our own, ruling vitality itself; and this not merely to the end of constructing the skeleton of a Protozoon, but of elaborating all the wonderful developments of life that were to follow in succeeding ages, and with re- ference to which the production and growth of this creature were initial steps. It is this mystery of design which really constitutes the "profound significance" of the foraminiferal skeleton. Another phenomenon of animality forced upon our notice by the Protozoa is that of the conditions of life in animals not individual, as we are, but aggregative and cumulative in in- definite masses. What, for instance, the relations to each other of the Polyps, growing together in a coral mass, or the separate parts of a Sponge, or the separate lobes of a Foram- inifer. In the case of the Polyps we may believe that there is special sensation in the tentacles and oral opening of each individual, and that each may experience hunger when in want, or satisfaction when it is filled with food, and that in- juries to one part of the mass may indirectly affect other pans, but that the nutrition of the whole mass may be as much unfelt by the individual Polyps as the processes r,oing on in our own liver are by us. So in the case of a large Sponge, or Foraminifer, there may be some special sensation in individual cells, pseudopods, or segments, and the general sensation may be very limited, while unconscious livmg powers pervade the 1'^ / Hi j i KM ■ ,!: I !|( Hi If? r « IP I 156 WHAT MAY BE LEARNED FROM EOZOON whole. In this matter of aggregiation of animals we have thus various grades. The Foraminifers and Sponges present us with the simplest of all, and that which most resembles the aggregation of buds in the plant. The Polyps and complex Bryozoons present a higher and more specialized type ; and though the bilateral symmetry which obtains in the higher animals is of a different nature, it still at least reminds us of that multiplication of similar parts which we see in the lower grades of being. It is worthy of notice here that the lower animals which shovv' aggregative tendencies present but im- perfect indications, cr none at all, of bilateral symmetry. Their bodies, like those of plants, are for the most part built up around a central axis, or they show tendencies to spiral modes of growth. It is this composite sort of life which is connected with the main geological function of the Foraminifer. While active sensation, appetite, and enjoyment pervade the pseudopods and external sarcode of the mass, the hard skeleton common to the whole is growing within ; and in this way the calcareous matter is gradually removed from the sea water, and built up in solid reefs, or in piles of loose foraminiferal shells. Thus it is the aggregative or common life, alike in Foraminifers as in Corals, that tends most powerfully to the accumulation of calcareous matter ; and those creatures whose life is of this complex character are best suited to be world builders, since the result of their growth is not merely a cemetery of their osseous remains, but a huge communistic ed^'ice, to which multitudes of lives have contributed, and in wnich successive generations take up their abode on the remains of their an- cestors. This process, so potent in the progress of the earth's geological history, began, as far as we know, with Eozoon. Whether, then, in questioning our proto-foraminifer, we have reference to the vital functions of its gelatinous sarcode, to the complexity and beauty of its calcareous test, or to its capacity -^•I*1 WHAT MAY BE LEARNED FROM EOZOON 157 ^■1 n- •e le for effecting great material results through the union of in- dividuals, we perceive that we have to do, not with a low condition of those powers which we designate life, but with their manifestation through the means of a simple organism ; and this in a degree of perfection wl"!.h we, from our point of view, would have in the first instance supposed impossible. If we imagine a world altogether destitute of life, we still might have geological formations in progress. Not only would volcanoes belch forth their liquid lavas and their stones and ashes, but t'>e waves and currents of the ocean and the rains and streams on the land, with the ceaseless decomposing action of the carbonic acid of the atmosphere, would be piling up mud, sand, and pebbles in the sea. There might even be some formation of limestone taking place where springs charged with bicarbonate of lime were oozing out on the land or the bottom of the waters. But in such a world all the carbon would be in the state of carbon dioxide, and all the limestone would either be diffused in small quantities through various rocks or in limited local beds, or in solution, perhaps as chloride of calcium, in the sea. Dr. Hunt has given chemical grounds for supposing that the most ancient seas v;ere largely supplied with this very soluble salt, instead of the chloride of sodium, or common salt, which now prevails in the sea water. Where in such a world would life be introduced ? on the land or in the waters ? All scientific probability would say in the latter.^ The ocean is now vastly more populous than the land. The waters alone afford the conditions necessary at once for the most minute and the grandest organisms, at once for the simplest and for others of the most complex character. Especially do they afford thi best conditions for * A recent writer (Simroth) has, however, undertaken to maintain the thesis tliat land life preceded tliat in the sea. It is unnecessary to say that he is an evolutionist, influenced by the necessity laid upon that philosophy to deduce whales, seals, etc., from land animals. 1^ II: m • r rt 158 WHAT MAV WE LKAKNKD 1- ROM EOZOOX those animals which suhsist in comijlcx coninuinilics, and which aggregate large (juantitics of mineral matter in their skeletons. So true is this that up to the j)resent time all the sjK'cies of Proto/:oa and of the animals most nearly allied to them are aquatic. Iwen in the waters, however, plant life, though possibly in very simple forms, must precede the animal. Let humble plants, then, be introduced in the waters, and they would at once begin to use the solar light for the purpose of decomposing carbonic acid, and forming carbon compounds which had not before existed, and which, indei)endcntly of vegetable life, would never have existed. At the same time lime and other mineral substances present in the sea water would be fixed in the tissues of these plants, either in a minute state of division, as little grains or Coccoliths, or in more solid masses like those of the Corallines and Nullipores. In this way a beginning of limestone formation might be made, and (juantities of carbonaceous and bituminous matter, resulting from the decay of vegetable substances might accumulate on the sea bottom. Now arises the opportunity for animal life. 'J'he plants have collected stores of organic matter, and rheir minute germs, along with microscopic species, are floating everywhere in the sea. The plant has fulfilled its function as far as the waters are concerned, and now a place is prepared for the animal. In what form shall it appear? Many of its higher forms, those which depend upon animal food or on the more complex plants for subsistence, would obviously be un- suitable. Further, the sea water is still too much saturated with saline matter to be fit for the higher animals of the waters. Still further, there may be a residue of internal heat forbidding coolness, and that solution of free oxygen which is an essential condition of existence to the higher forms of life. Something must be found suitable for this saline, imperfectly oxygenated, tepid sea. Something, too, is wanted that can aid in introduc- WHAT MAY j;i-: LEAKNKI) FROM KOZOON '59 ^ iiig conditions more favoiirahlL- to higher h'fc in the future. Our experience of the modern world shows us that all these conditions can be better fulfilled by the Protozoa than by any other creatures. They can live now ccjually in those great depths of ocean where the conditions are most unfavourable to other forms of life, and in tepid unhealthy pools overstocked with vegetable matter in a state of putridity. They form a most suitable basis for higher forms of life. They have re- markable powers of removing mineral matters from the waters and of fixing them in solid forms. So, in the fitness of things, a girantic Foraminifer is just what we need, and after it has spread itself over the mud and rock of the primeval seas, and built up extensive reefs therein, other animals may be intro- duced, capable of feeding on it, or of sheltering themselves in its stony masses, and thus we have the appropriate dawn of animal life. But what are we to say of the cause of this new series of facts, so wonderfully superimposed upon the merely vegetable and mineral ? Must it remain to us as an act of creation, or was it derived from some pre-existing matter in which it had been potentially present ? vScience fails to inform us, but con- jectural " phylogeny " steps in and takes its place. Haeckel, the prophet of this new philosophy, waves his magic wand, and simple masses of sarcodc spring from inorganic matter, and form diffused sheets of sea slime, from which are in time separated distinct amoeboid and foraminiferal forms. Ex- perience, however, gives us no facts whereon to build this supposition, and it remains neither more nor less scientific or certain than that old fancy of the Egyptians, which derived animals from the fertile mud of the Nile. If we fail to learn anything of the origin of Eozoon, and if its life processes are just as inscrutable as those of higher creatures, we can at least enquire as to its history in geolo- logical time. In this respect we find, in the first place, that r r m/^ IMAGE EVALUATION TEST TARGET (MT-3) 1.0 IM 112.5 I.I 1.25 M 1.8 u mil 1.6 V] <^ /a m /, f s .■» o / ^^ %. 4? V iV N> % V %^^ ;\ <«■ 7 I I ' I '■ . I I \% !' 1 ■ : ■ I P' '• i ! 1 Iff' ji ■ I ill l60 WHAT MAY BE LEARNED FROM EOZOON the Protozoa have not had a monopoly in their profession of accumulators of calcareous rock. Originated by Eozoon in the old Laurentian time, this pro- cess has been proceeding throughout the geological ages ; and while Protozoa, equally simple with the great prototype of the race, have been and are continuing its function, and producing new limestones in every geological period, and so adding to the volume of the successive formations, new workers of higher grades have been introduced, capable of enjoying higher forms of animal activity, and equally of labouring at the great task of continent building; of existing, too, in seas less rich in mineral substances than those of the Eozoic time, and for that very reason better suited to higher and more skilled artists. It is to be observed in connection with this, that as the work of the Foraminifers has thus been assumed by others, their size and importance have diminished, and the larger forms of more recent times have some of them been fain to build up their hard parts of cemented sand instead of limestone. When the marvellous results of recent deep-sea dredgings were first made known, and it was found that chalky foram- iniferal earth is yet accumulating in the Atlantic, with sponges and sea urchins, resembling in many respects those whose remains exist in the chalk, the fact was expressed by the state- ment that we still live in the chalk period. Thus stated the conclusion is scarcely correct. We do not live in the chalk period, but the conditions of the chalk period still exist in the deeper portions of the sea. We may say more than this. To some extent the conditions of the Laurentian period still exist in the sea, except in so far as they have been removed by the action of the Foraminifera and other limestone builders. To those who can realize the enormous lapse of time involved in the geological history of the earth, this conveys an impression almost of eternity in the existence of this oldest of all the families of the animal kingdom. •^^^^mTT^SBBT WHAT MAY BE LEARNED FROM EOZOON l6l We are still more deeply impressed with this when we bring into view the great physical changes which have occurred since the dawn of life. "When we consider that the skeletons of Eo; oon contribute to form the oldest hills of our continents ; that they have been sealed up in solid marble, and that they are associated with hard crystalline rocks contorted in the most fantastic manner ; that these rocks have almost from the beginning of geological time been undergoing waste to supply the material of new formations ; that they have witnessed in- numerable subsidences and elevations of the continents ; and that the greatest mountain chains of the earth have been built up from the sea since Eozoon began to exist, — we acquire a most profound impression of the persistence of the lower forms of animal life, and know that mountains may be removed and continents swept away and replaced, before the least of the humble gelatinous Protozoa can finally perish. Life may be a fleeting thing in the individual, but as handed down through successive generations of beings, and as a constant animating power in successive organisms, it appears, like its Creator, eternal. This leads to another and very serious question. How long did lineal descendants of Eozoon exist, and do they still exist ? We may for the present consider this question apart from ideas of derivation and elevation into higher planes of existence. Eozoon as a species, and even as a genus, may cease to exist with the Eozoic age, and we have no evidence whatever that any succeeding creatures are its modified descendants. As far as their structures inform us, they may as much claim to be original creations as Eozoon itself. Still descendants of Eozoon may have continued to exist, though we have not yet met with them. I should not be surprised to hear of a veritable speci- men being some day dredged alive in the Atlantic or the Pacific. It is also to be observed that in animals so simple as this many varieties may appear, widely different from the «^ I 1 / 1 r ' ' ^ 1 ' r,if ' I I . * i * i rf i I I , 162 WHAT MAY Bt LEARNED FROM EOZOON original. In these the general form and habit of life are the most likely things to change, the minute structures much less so. We need not, therefore, be surprised to find its descend- ants dim'nishing in size or altering in general form, while the characters of the fine tubulauon and of the canal system would remain. We need not wonder if any sessile Foraminifer of the Nummuline group should prove to be a descendant of Eozoon. It would be less likely that a Sponge or a Foraminifer of the Rotaline type should originate from it. If one could only secure a succession of deep-sea limestones with Foraminifers extending all the way from the Laurentian to the present time, I can imagine nothing more interesting than to compare the whole series, with the view of ascertaining the limits of descent with variation, and the points where new forms are introduced. We have not yet such a series, but it may be obtained ; and as these creatures are eminently cosmopolitan, occurring over vastly wide areas of sea bottom, and are very variable, they would afford a better test of theories of derivation than any that can be obtained from the more locally distributed and less variable animals of higher grade. I was much struck with this recently, in examining a series of Foraminifera from the Cretaceous of Manitoba, and comparing them with the varietal forms of the same species in the interior of Nebraska, 500 miles to the south, and with those of the English chalk and of the modern seas. In all these different times and places we had the same species. In all they existed under so many varietal forms passing into each other, that in former times every species had been multiplied by naturalists into several. Yet, in all, the identical varietal forms were repeated with the most minute markings the same. Here were at once constancy the most remarkable, and variations the most extensive. If we dwell on the one to the exclusion of the other, we reach only one-sided conclusions, imperfect and unsatisfactory. By taking both into connection we can alone realize the full significance ^aSttjU WHAT MAY UE LEARNED FROM EOZOON 163 e of the facts. We cannot yet obtain such series for all geological time ; but it may even now be worth v.hile to enquire, What do we know as to any modification in the case of the primeval Foraminifers, whether with reference to the derivation from them of other Protozoa or of higher forms of life ? There is no link in geological fact to connect Eozoon with any of the Mollusks, Radiates, or Crustaceans of the succeed- ing Cambrian. What may l)e discovered in the future we can- not conjecture ; but at present these stand before us as distinct creations. It would of course be more probable that Eozoon should be the ancestor of some of the Foraminifera of the Primordial age, but strangely enough it is very dissimilar from all these, exce; ^. Cryptozoum and some forms of Stromatopora ; and here, as alieady stated, the evidence of minute structure fails to a great extent. Of actual facts, therefore, we have none ; and those evolutionists who have regarded the dawn animal as an evidence in their favour have been obliged to have recourse to supposition and assumption. AVe may imagine Eozoon itself, however, to state its experi- ence as follows : — " I, Eozoon Canadense, being a creature of low organization and intelligence, and of practical turn, am no theorist, but have a lively appreciation of such facts as I am able to perceive. I found myself growing upon the sea bottom, and know not whence I came. I grew and flourished forages, and found no let or hindrance to my expansion, and abundance of food was always floated to me without my having to go in search of it. At length a change came. Certain creatures with hard snouts and jaws began to prey on me. AVhence they came I know not ; I cannot think that they came from the germs which I had disi ..rsed so abundantly throughout the ocean. Unfortunately, just at the same time Hme became a little less abundant in the waters, perhaps because of the great demands I myself had made, and thus it was not so easy as before to produce a thick supplemental skeleton for defence. li 7 i 1 : i It' If ml 164 WHAT MAY BE LEARNED FROM EOZOON So I had to give way. I have done my best to avoid extinc- tion ; but it is clear that I must at length be overcome, and must either disappear or subside into a humbler condition, and that other creatures better provided for the new conditions of the world must take my place." In such terms we may suppose that this ntriarch of the seas might tell his history, and mourn his destiny, though he might also congratulate himself on hav- ing in an honest way done his duty and fulfilled his function in the world, leaving it to other and perhaps wiser creatures to dispute as to his origin and fate, while perhaus much less perfectly fulfilling the ends of their own existence. Thus our dawn animal has positively no story to tell as to its own introduction or its transmutation into other forms of existence. It leaves the mystery of creation where it was, but in connection with the subsequent history of life we can learn from it a little as to the laws which have governed the succes- sion of animals in geological time. First, we may learn that the plan of creation has been progressive, that there has been an advance from the few low and generalized types of the primaeval ocean to the more numerous, higher, and more specialized types of more recent times. Secondly, we learn that the lower types, when first introduced, and before they were subordinated to higher forms of life, existed in some of their grandest modifications as to form and complexity, and that in succeeding ages, when higher types were replacing them, they were subjected to decay and degeneracy. Thirdly, we learn that while the species has a limited term of existence in geological time, any large type of animal existence, like that of the Foraminifera or Sponges, for example, once introduced, continues and finds throughout all the vicissitudes of the earth some appropriate residence. Fourthly, as to the mode of in- troduction of new types, or whether such creatures as Eozoon had any direct connection with the subsequent introduction of Mollusks, Worms, or Crustaceans, it is altogether silent, nor WHAT ^rAY BE LEARNED FROM EOZOON 165 fy, we ice in hat of [uced, earth |of in- )zoon iction It, nor can it predict anything as to the order or manner of their introduction. Had we been permitted to visit the Laurentian seas, and to study Eozoon and its contemporary Protozoa when alive, it is plain that we could not have foreseen or predicted from the consideration of such organisms the future development of life. No amount of study of the prototypal Foraminifer could have led us distinctly to the conception of even a Sponge or a Polyp, much less of any of the higher animals. Why is this ? The answer is that the improvement into such higher types does not take place by any change of the elementary sarcode, either in those chemical, mechanical, or vital properties which we can study, but in the adding to it of new structures. In the Sponge, which is perhaps the nearest type of all, we have the movable pulsating cilium and true animal cellular tissue, and along with this the spicular or fibrous skeleton, these structures leading to an entire change in th2 mode of life and subsistence. In the higher types of animals it is the same. Even in the highest we have white blood corpuscles and germinal matter, which, in so far as we know, carry on no higher forms of life than those of an Amoeba ; but they are now made subordinate to other kinds of tissues, of great variety and complexity, which never have been observed to arise out of the growth of any Protozoon. There would be only a few conceivable inferences which the highest finite intelligence could deduce as to the development of future and higher animals. He might infer that the Foraminiferal sarcode, once introduced, might be the substratum or founda- tion of other but unknown tissues in the higher animals, and that the Protozoon type might continue to subsist side by side with higher forms of living things, as they were successively introduced. He might also infer that the elevation of the animal kingdom would take place with reference to those new properties of sensation and voluntary motion in which the humblest animals diverge from the life of the plant. S. E. 12 T 1 66 WAHT MAY BE LEARNED FROM EOZOON ■i- i i ^. It is important that these points should be clearly before our minds, because there has been current of late among natural- ists a loose way of writing with reference to them, which seems to have imposed on many who are not naturalists. It has been said, for example, that such an organism as Eozoon may include potentially all the structures and functions of the higher animals, and that it is possible that we might be able to infer or calculate all these with as much certainty as we can calcu- late an eclipse or any other physical phenomenon. Now, there is not only no foundation in fact for these assertions, but it is, from our present standpoint, not conceivable that they can ever be realized. The laws of inorganic matter give no data whence any a priori deductions or calculations could be made as to the structure and vital forces of the plant. The plant gives no data from which we can calculate the functions of the animal. The Protozoon gives no data from which we can calculate the specialties of the Mollusk, the Articulate, or the Vertebrate. Nor, unhappily, do the present conditions of life of themselves give us any sure grounds for pred'cting the new creations that may be in store for our old planet. Those who think to build a philosophy and even a religion on -:uch data are mere dreamers, and have no scientific basis for their dogmas. They are as blind guides as our primaeval Protozoon himself would be in matters whose real solution lies in the harmony of our own higher and immaterial naturo with the Being who is the Author of all life — the Father " from whom every family in heaven and earth is named." Kkferences: — "Life's Dawn on Earth." London, 1885. Specimens of Eozoon in the Peter Reclpath Museum, Montreal, 1888. THE APPARITION AND SUCCESSION OF ANIMAL FORMS. DEDICATED TO THE MEMORY OF THE EMINENT SWISS AND AMERICAN ZOOLOGIST LOUIS AGASSIZ, TnK Founder oi- the Modern School of American Biology, AND of SIR RICHARD OWEN, A Great ani:) Philosophical Naturalist, TO whose Teaching I and very many Others owe our earliest introduction to the Principle of Homology IN THE Animal Kingdom. ■ t ' ■ :l i I It « i ^>i! fi Old forms of Trilobites, from the Lower Cambrian (p. 173 e( set/.) Oletidlus 77ioinpsoni, Emmons. Agnosius vir, Matthew. ParndoxUcs legina, Matthew. CHAPTER VII. THE APPARITION AND SUCCESSION OF ANIMAL FORMS. TIME was when naturalists were content to take nature as they found it, without any over-curious inquiries as to the origin of its several parts, or the changes of which they might be susceptible, (jeology first removed this pleasant state of repose, by showing that all our present species had a beginning, and were preceded by others, and these again by others. Geologists were, however, too much occupied with the facts of the succession to speculate on the ultimate causes of the appearance and disappearance of species, and it re- mained for zoologists and botanists, or as some prefer to call themselves, biologists, to construct hypotheses or theories to account for the ascertained fact that successive dynasties of species have succeeded each other in time. I do not propose in this paper so much to deal with the various doctrines as to derivation and development now current, as to ask the ques- tion, What do we actually know as to the origin and history of life on our planet ? This great question, confessedly accompanied with many difficulties and still waiting for its full solution, has points of intense interest both for the Geologist and the Biologist. " If," says the great founder of the uniformitarian School of Geology, " the past duration of the earth be finite, then the aggregate of geological epochs, however numerous, must con- stitute a mere moment of the past, a mere infinitesimal portion of eternity." Yet to our limited vision, the origin of life fades I&9 W „l lyo THE SUCCESSION OF ANIMAL FORMS I ■1 ! » ■ away in the almost illimitable depths of past time, and we arc ready to despair of ever reaching, by any process of discovery, to its first steps of progress. At what time did life oegin ? In what form did dead matter first assume or receive those mysterious functions of growth, reproduction and sensation ? Only when we picture to ourselves an absolutely lifeless world, destitute of any germ of life or organization, can we realize the magnitude of these questions, and perceive how necessary it is to limit their scope if we would hope for any satisfactory answer. A\'e may here dismiss altogether that form in which these (juestions present themselves to the biologist, when he experi- ments as to the evolution of living forms from dead liquids or solids attacking the unsolved problem of spontaneous genera- tion. Nor need wc enter on the vast field of discussion as to ii'!odern animals and plants opened up by Darwin and others. I shall confine myself altogether to that historical or palceonto- logical aspect in which life presents itself when we study the fossil remains entombed in the sediments of the earth's crust, and which will enable me at least to show why some students of fossils liesitate to give in their adhesion to any of the cur- rent notions as to the origin of species. It will also be desir- able to avoid, as far as possible, the use of the term "evolution," as this has recently been employed in so many senses, whether of development or causation, as to have become nearly useless for any scientific purpose ; and that when I speak of creation of species, the term is to be understood not in the arbitrary sense forced on it by some modern writers, but as indicating the continuous introduction of new forms of life under definite laws, but by a power not emanating from within themselves, nor from the inanimate nature surrounding them.^ ' The terms Deri''ition, Development and Causation have clear and definite meanings, and it is preferable, wherever possible, to use one or other of these. ilrillliM.i I . THE SUCCESSION OF ANIMAL FORMS 171 If we were to follow the guidance of those curious analogies which present themselves when we consider the growth of the individual plant or animal from the spore or the ovum, and the development of vegetable and animal life in geological time — analogies which, however, it must be borne in mind can have no scientific value whatever, inasmuch as that similarity of conditions which alone can give force to reasoning from an- alogy in matters of science, is wholl) wanting — we should ex- pect to fm( in the oldest rocks embryon> forms alone, but of course embryonic forms suited to exist and reproduce them- selves independently.^ I need not say to palaeontologists that this is not what we actually find in the primordial rocks. I need but to remind them of the early and remarkable development of such forms as the Trilobites, the Lingulidce and the Pteropods, all of them highly complex and specialized types, and remote from the embryonic stages of the groups to which they several^ b'^long. In the case of the Trilobites, one need merely consider the beautiful symmetry of their parts, both transversely and longi- tudinally, their division into distinct regions, the necessary com- plexity of their muscular and nervous systems, their highly complex visual organs, the superficial ornamentation and micro- scopic structure of their crusts, their advanced position among Crustaceans, indicated by their strong affinity with the Arach- nidans or spiders and scorpions. (See figures prefixed.) * I may be pardoned for taking an example of the confusion of thought which this mode of reasoning has introduced into Biology from a clever article in tlie Contemporary written by a very able and much-esteemed biologist. lie says : " The morphological distance betwe>.n a newly hatched frog's tadpole and the adult frog is almost as great as that between the adult lancelet and the newly hatched larvx of the lamprey." The "mor- phological distance" truly, but what of the physiological distance between the young and adult of the same animal anil two adult animals between which is placed the great gulf of specific and generic diversity which with- in human experience neither has been known to pass ? j^' 172 THE SUCCESSION OF ANLMAL FORMS II t-*l All these characters give them an aspect far from embryonic, while, as Barrande has pointed out, this advanced position of the group has its significance greatly strengthened by the fact that in early primordial times we have to deal not with one species, but with a vast and highly differentiated group, embrac- ing forms of many and varied subordinate types. As we shall see, these and oiher early animals may be regarded as of generalized types, but not as embryonic. Here, then, meets us at the outset the fact that in as far as the great groups of annu- lose and molluscous animals are concerned, we can trace these back no fai her than to a period in which they appear already highly advanced, much specialized and represented by many diverse forms. Either, therefore, these great groups came in on this high initial plane, or we have scarcely reached half wny back in the life-history of our planet. We have, here, however, by this one consideration, attained at once to two great and dominant laws regulating the his- tory of life. First, the lav- of continuity, whereby new forms come in successively, throughout geological time, though, as we shall see, with periods of greater or ^Co-^ frequency. Secondly, the law of specialization of types, whereby general- ized forms are succeeded by those more special, and this pro- bably connected with the growing specialization of the inorganic world. It is this second law which causes the parallelism between the history of successive species and that of the embryo. We have already considered the claims which Eozoon and its contemporaries may urge to recognition, as beginnings of life ; but when we ascend from the Laurentian beds, we find ourselves in a barren series of conglomerates, sandstones, and other rocks, indicating shore rather than sea conditions, and remarkably destitute of indications of life. These are the Huronian beds, and possibly other series associated with them. They have afforded spicules of sponges, casts of burrows of ~" ' iiiWM THE SUCCESSION OF ANIMAL FORMS 173 worms, obscure forms, which may represent crustaceans or molhisks, markings of unknown origin, and some laminated forms which may perhaps represent remains of Eozoon, though their structures are imperfectly preserved. These are sufficient to show that marine life continued in some forms, and to en- courage the hope that a rich pre-Cambrian fauna may yet be discovered. But let us leave for the present the somewhat isolated case of Eozoon, and the few scattered forms of the Huronian, and go on farther to the early Cambrian fauna. This is graphi- cally presented to us in the sections in South Wales, as de- scribed by Hicks. Here we find a nucleus of ancient rocks, supposed to be Eaurentian, though in mineral character more nearly akin to the Huronian, but which have hitherto afforded no trace of fossils. Resting unconformably on these is a series of slates and sandstones, regarded as Lower Cambrian, the Caerfai group of Hicks, and which are the earliest holding organic remains. The lowest bed which contains indications of life is a red shale near the base of the series, which holds a few organic remains. The species are a Lingiilella^ worm bur- rows and a Trilobite.^ Supposing these to be all, it is remark- able that we have no Protozoa or Corals or Echiiioderms, and that the types of Brachiopods and Crustaceans are of compara- tively modern affinities. Passing upward through 1,000 feet of barren sandstone and shale, we reach a zone in which many Trilobites of at least five genera are found, along with Pteropods, Brachiopods and Sponges. Thus it is that life comes in at the base of the Cambrian in Wales, and it may be regarded as a fair specimen of the facts as they appear in the earlier fossiliferous beds succeeding the Laurentian. Taking the first of these groups of fossils, we may recognise in the worms representatives of those that si'U haunt our shores, in the Trilobite a Crustacean or Arachn(»id of no mean grade. ' Probably of the genus O.enelliis. \tr 1 f m i 1 i 1/4 THE SUCCESSION OF ANIMAL FORMS u I The Liiigukllce^ whether we regard them as molluscoids, or, with Professor Morse, as singularly specialized worms, represent a peculiar and distinct type, handed down, through all the vicissitudes of the geological ages, to the present day. Had the Primordial life begun with species altogether inscrutable and unexampled in succeeding ages, this would no doubt have been mysterious ; but next to this is the mystery of the oldest forms of life being also among the newest. One great fact shines here with the clearness of noon-dav. Whatever the origin of these creatures, they represent families which have endured till now in the struggle for existence without either elevation or degradation. Here, again, we may formulate an- other creative law. In every great group there are some forms much more capable of long continuance than others. Lingula among the Brachiopods is a marked instance. But when, with Hicks, we surmount the mass of barren beds underlying these remains, which from its unfossiliferous charac- ter is probably a somewhat rapid deposit of Arctic mud, like that which in all geological time has constituted the rough fill- ing of our continental formations, and have suddenly sprung upon us many genera of Trilobites, including the fewest-jointed anc most many-jointed, the smallest and the largest of their race, our astonishment must increase, till we recognise the fact that we are now in the presence of another great law of creation, which provides that every new type shall be rapidly extended to the extreme limits of its power of adaptation. That this is not merely local is evidenced by the researches of Matthew and Walcott in the oldest Cambrian of America, where a similar succession occurs, but with this difference, that in the wider area presented by the American continent we find a greater variety of forms of life. Walcott records up to 1892 no less than 67 genera and 165 species in the oldest Cambrian of America. These include representatives of the Sponges, Hydroids, Corals, Echinoderms, Worms, Brachiopods, Bivalve THE SUCCESSION OF ANIMAL FORMS ^75 ;!i and Univalve Mollusks and Crustaceans, or in other words, all the leading groups of invertebrate animals that we find in the sea at present. Of these the dominant group is the Crustaceans, including Trilobites, numbering one-third of the whole ; and these with the univalve Mollusks and the Brachiopods constitute the majority, the other groups having comparatively few species. AVhat a marvellous incoming of life is here ! Walcott may well say that on the theory of gradual development we must suppose that life existed at a period far before the Cambrian — as far, indeed, as the Cambrian is before our own time. But this would mean that we know only half of the history of life ; and perhaps it is more reasonable to suppose that when the conditions became favourable, it came in with a rush. Before considering the other laws that may be inferred from these facts, however, let us in imagination transfer ourselves back to the Primordial age, and suppose that we have in our hands a living specimen of one of the larger Trilobites, recently taken from the sea, flapping vigorously its great tail, and full of life and energy ; an animal larger and heavier than the modern king-crab of our shores, furnished with all the complexity of external parts for which the crustaceans are so remarkable, and no doubt with instincts and feelings and modes of action as pro- nounced as those of its modern allies, and, if Woodward's views are correct, on a higher plane of rank than the king-crab itself, inasmuch as it is a composite type connecting Limuli with Isopods, and even with scorpions. We have obviously here, in the appearance of this great Crustacean or Arachnoid, a repe- tition of the facts which we met with in Eozoon ; but how vast the interval between them in geological time, and in zoological rank ! Standing in the presence of this testimony, I think il is only right to say that we possess no causal solution of the appearance of these early forms of life ; but in tracing them and their successors upward through the succeeding ages, ,ve may hope at least to reach some expressions of the laws of T^T" u ■; * 176 THE SUCCESSION OF ANIMAL FORMS \ 1 I y their succession, in possession of which we may return to attack the mystery of their origin. First, it must strike every observer that there is a great same- ness of plan throughout the whole history of marine inverte- brate life. If we turn over the pages of an illustrated textbook of geology, or examine the cases or drawers of a collection of fossils, we shall find extending through every succeeding for- mation, representative forms of Crustaceans, Mollusks, Corals, etc., in such a manner as to indicate that in each successive period there has been a reproduction of the same type with modifications ; and if the series is not continuous, this appears to be due rather to abrupt physical changes ; since sometimes, where two formations pass into each other, we find a gradual change in the fossils by the dropping out and introduction of species one by one. Thus, in the whole of the great Palaeozoic Period, both in its Fauna and Flora, we have a continuity and similarity of a most marked character. It is evident that there is presented to us in this similarity of the forms of successive faunas and floras, a phenomenon which deserves very careful sifting as to the question of identity or diversity of species. The data for its comprehension must be obtained by careful study of the series of closely allied forms occurring in successive formations, and the great and undisturbed areas of the older rocks in America seem to give special facilities for this, which should be worked, not in the direction of constituting new species for every slightly diver- gent form, but in striving to group these forms into large specific types. ^ There is nothing to preclude the supposition that some of the groups mentioned in the note are really specific types, with * The Rynchonellai of the type of A', plena, the Oithids, of the type of 0, testtuiinaria, th^- Strophomeiue of the types of S. alteriiata and S. Rhoni- boidalis, the Atrypae of the type of A. rdicularis, furnish cases in point among the Brachiopods. •i( THE SUCCESSION OF ANIMAL FORMS -^77 numerous race modifications. My own provisional conclusion, based on the study of Palreozoic plants, is that the general law will be foi nd to be the existence of distinct specific types, in- dependent of each other, but liable in geological time to a great many modifications, which have often been regarded as distinct species.^ While this unity of successive faunce at first sight p/esents an appearance of hereditary succession, it loses much of this character when we consider the number of new types introduced without apparent predecessors, the necessity that there should be similarity of type in successive faunne on any hypothesis of a continuous plan ; and above all, the fact that the recurrence of representative species or races in large proportion marks times of decadence rather than of expansion in the types to which they belong. To turn to another period, this is very manifest in that singular resemblance which obtains between the modern mammals of South America and Australia, and their immediate fossil predecessors — the phenomenon being here manifestly that of decadence of large and abundant species into a few depauperated represe.itatives. This will be found to be a very general law, elevation being accompanied by the apparent abrupt appearance of new types and decadence by the apparent continuation of old species, or modifications of them. This resemblance with difference in successive faunas also connects itself very directly with the successive elevations and depressions of our continental plateaus in geological time. Every great Palaeozoic limestone, for example, indicates a depression with succeeding elevation. On each elevation marine animals were driven back into the ocean, and on each depression swarmed in over the land, reinforced by new species, either then introduced, or derived by migration from other localities. In like manner, on every depression, land » "Geological History of Plants." i i I' Vf i; I ( 1 78 THE SUCCESSION OF ANIMAI> FORMS plants and animals were driven in upon insular areas, and on re-elevation, again SDread themselves widely. Now I think it will be found to be a law here that periods of expansion were eminently those of introduction of new specific types, and periods of contraction those of extinction, and also of continu- ance of old types under new varietal forms. It must also be noticed that all the leading types of in- vertebrate life were early introduced, that change within these was necessarily limited, and that elevation could take place mainly by the introduction of the vertebrate orders. So in plants. Cryptogams early attained their maximum as well as Gymnosperms, and elevation occurred in the introduction of PhaenogL . and this not piecemeal, but as we shall see in a succeeding chapter, in great force at once. We may further remark the simultaneous appearance of like types of life in one and the same geological period, over widely separated regions of the earth's surface. This strikes us es- pecially in the comparatively simple and homogeneous life- dynasties of the Palaeozoic, when, for example, we find the same types of Silurian Graptolites, Trilobites and Brachiopods ap- pearing simultaneously in . istralia, America and Europe. Perhaps in no department is it more impressive than in the introduction of the Devonian and Carboniferous Ages of that grand cryptogamous ^and gymnospermous flora which ranges from Brazil to Spitzbergen, and from Australia to Scotland, accompanied in all by^the same groups of marine invertebrates. Such facts may depend either on that long life of specific types which gives them ample tirr.e to spread to all possible habitats, before their extinction, or on some general law where- by the conditions suitable to similar types of life emerge at one time in all parts of the world. Both causes may be influential, as the one does not exclude the other, and there is reason to believe that both are natural facts. Should it be ultimately proved that species allied and representative, but distinct in THE SUCCESSION OF ANIMAL FORMS 1/9 origin, come into being simultaneously everywhere, we shall arrive at one of the laws of creat'on, and one probably con- nected with the gradual chmge of the physical conditions of the world. Another general truth, obvious from the facts which have been already collected, is the periodicity of introduction of species. They come in by bursts or flood tides at particular points of time, while these great life waves are followed and preceded by times of ebb in which little that is new is being produced. We labour in our investigation of this matter under the disadvantage that the modern period is evidently one of the times of pause in the creative work. Had our time been that of the early Tertiary or early Mesozoic, our views as to the question of origin of species might have been very dif- ferent. It is a striking fact, in illustration of this, that since the glacial age no new species of mammal, except, possibly, man himself, can be proved to have originated on our continents, while a great number of large and conspicuous forms have disappeared. It is possible that the proximate or secondary causes of the ebb and flow of life production may be in part at least physical, but other and more important efficient causes may be behind these. In any case these undulations in the history of life are in harmony with much that we see in other departments of nature. It results from the above and the immediately preceding statement, that specific and generic types enter on the stage in great force, and gradually taper off towards extinction. They should so appear in the geological diagrams made to illustrate the succession of living beings. This applies even to those forms of life which come in with fewest species and under the most humble guise. What a remarkable swarming, for ex- ample, there must have been of Marsupial Mammals in ihe early Mesozoic, and in the Coal formation the only known Pulmonale snails, five or six in number, belong to four generic < i 3. E, 1.5 J^;i' i8o THE SUCCESSION OF ANIMAL FORMS 1! !P !Bt| J types, while the Myriapods and Amphibians alike appear in a crowd of generic forms. I have already referred to the permanence of species in geological time. We may now place this in connection with the law of rapid origination and more or less continuous transmission of varietal forms, A good illustration will be afforded by a group of species with which I am very familiar, that which came into our seas at the beginning of the Glacial age, and still exists. AVith regard to their permanence, it can be affirmed that th'^ shells now elevated in Wales to 1,200, and in Canada to 600 feet above the sea, and which lived be- fore the last great revolution of our continents — a period very remote as compared with haman history — differ in no tittle from their modern successors after hundreds or thousands of generations. It can also be affirmed that the more variable species appear under precisely the same varietal forms then as now, though these varieties have changed much in their local distribution. The real import of these statements, which might also be made with regard to other groups, well known to palae- ontologists, is of so great significance that it can be realized only after we have thought of the vast time and numerous changes through which these humble creatures have survived. I may call in evidence here a familiar New England animal, the common sand clam, Af)'a arenaria^ and its relative My a tnincata^ the short sand clarri, which now inhabit together all the northern seas ; for the Pacific specimens, from Japan and California, though differently named, are undoubtedly the same. Mya tnmcata appears in Europe in the Coralline Crag, and was followed by M. arenaria in the . Red Crag. Both shells occur in the Pleistocene of America, and their several varietal forms had already developed themselves in the Crag, and re- main the same to-day ; so that these humble mollusks, littoral in their habits, and subjected to a great variety of conditions, have continued for a very long period to construct their shells THE SUCCESSION OF ANIMAL FORMS l8l precisely as at present; while in many places, as on the Lower St. Lawrence, we find them living together on the same banks, and yet preserving their distinctness.' Nor are there any in- dications of a transition between the two species. I might make similar statements with regard to the Astartes, Bucci- nums and Tellinre of the drift, and could illustrate them by extensive series of specimens from my own collections. Another curious illustration is that presented by the Tertiary and modern faunae of some oceanic islands far separated from the continents. In Madeira and Porto Santo, for example, according to Lyell, we have fifty-six species of land shells in the former, and forty-two in the latter, only twelve being com- mon to the two, though these islands are only thirty miles apart. Now in the Pliocene strata of Madeira and Porto Santo we find thirty-six species in the former, and thirty-five in the latter, of which only eight per cent, are extinct, and yet only eight are common to the two islands. Further, there seem to be rto transitional forms connecting the species, and of some of them the same varieties existed in the Pliocene as now. The main difference in time is the extinction of some species and the introduction of others without known connect- ing links, and the fact that some species, plentiful in the Pliocene, are rare now, and vice versa. All these shells differ from those of modern Europe, but some of them are allied to Miocene species of that continent. Here we have a case of continued existence of the same forms, and in circumstances which, the more we think of them, the more do they defy all our existing theories as to specific origins. Perhaps some of the most remarkable facts in connection with the permanence of varietal forms of species are those furnished by that magnificent flora which burst in all its majesty on the American continent in the Cretaceous period, and still survives among us, even in some of its specific types. ^ Paper in Record of Science, on Shells at Little Metis. I :i 'il' I k .fi' IS2 THE SUCCESSION OF ANIMAL FORMS I say survives ; for wc have but a remnant of its forms living, and comparatively little that is new has probably been added since. The confusion which has obtained as to the age of this flora, and its mistaken reference to the Miocene Tertiary, have arisen in part from the fact that this modern flora was in its earlier times contemi)orary with Cretaceous animals, and survived the gradual change from the animal life of the Creta- ceous down to that of the Eocene, and even of the Miocene. In collections of these plants, from what may be termed beds of transition from the Cretaceous to the Tertiary, we fmd many l)lants of modern species, or so closely related that they may be mere varietal forms. Some of these will be mentioned in the next paper, and they show that modern plants, some of them small and insiguificantj others of gigantic size, reach back to a time when the Mesozoic Dinosaurs were becoming extinct, and the earliest Placental mammals being introduced. Shall we say that these plants have propagated themselves unchanged for half a million of years, or more ? ' Take from the western Mesozoic a contrasting yet illustrative fact. In the lowest Cretaceous rocks of Queen Charlotte's Island, Mr. Richardson and Dr. G. M. Dawson find Ammon- ites and allied Cephalopods similar in many respects to those discovered farther south by the California Survey, and Mr. Whiteaves finds that some of them are apparently not distinct from species described by the Palaeontologists of the Geological Survey of British India. On both sides of the Pacific these shells lie entombed in solid rock, and the Pacific rclls between, as of yore. Yet these species, genera, and even families are all extinct — why, no man can tell, while land plants that must have come in while the survivors of these Cephalopods still lived, reach down to the present. How mysterious is all this, * Among these are living species of ferns, one of them our common "Sensitive Fern," of Eastern America, two species of Hazel still extant, and Sequoias or giant pines, like those now surviving in California. THE SUvXESSION OF ANIMAL FORMS 183 and how strongly does it show the independence in some sense of merely physical agencies on the part of the manifestations of life ! We have naturally been orcupied hitherto with the lower tribes of animals and with plant life, because these are pre- dominant in the early ages of the earth. Let us turn now to the history of vertebrate or back-boned animals, which i)resents some peculiarities special to itself. Many years ago Pander ^ described and figured from the Cambro-silurian of Russia, a number of minute teeth, some conical and some comb-like, which he referred to fishes, and to that low form of the fish type represented by the modern lampreys. Much doubt was thrown on this determination, more especially a? the teeth seemed to be composed not of bone earth, but of carbonate of lime, and it was suggested that they may have belonged to marine worms, or to the lingual ribbons of Gastropod mol- lusks. Some confirmatory evidence seems to have been sup- plied by the discovery of great numbers of similar forms in the shales of the coal formation of Ohio, by the late Dr. Newberry. I have had an opportunity to examine these, and find that they consist of calcium phosphate,- or bone earth, and that their microscopic structure is not dissimilar from that of the teeth of some of the smaller sharks (l)iplodus) found with them. I have therefore been inclined to believe that there may have already been, even in the Cambrian or Lower Silurian seas, true fishes, related partly to the lampreys and partly to sharks ; so that the history of the back-boned animals may have gone nearly as far back as that of their humbler relations. This conjecture has recently received further support from the discovery in rocl:s of Lower Silurian age, in Colorada of a veritable bone bed, rich in fragmentary remains of fishes. * More recently Rohan has described conical teeth (St. Petersburg Academy, 1889), but I have not seen his paper. ^ Analysis of Dr. B. J. Harrington. wrr fr 184 THE SUCCESSION OF ANIMAL FORMS I «i>> 1 1 1 They are unfortunately so comminuted as to resemble the debris of the food of some larger animal ; but in so far as I can judge from specimens kindly given to me/ they resemble the bony coverings of som : of the familiar fishes of the Devonian. Thus they would indicate, with Pander's and Rohan's speci- mens, already two distinct types of fishes as existing almost as early as the higher invertebrates of the sea. In the Silurian (Upper Silurian of Murchison) we have un- doubted evidence of che same kind, on both sides of the Atlantic, in teeth and spines of sharks, and the plates which protected the heads and bodies of the plate-covered fishes (Placo-ganoids). But it is in the Devonian that these types appear to culminate, and we have added to th(M"n that remark- able type of " lung fish/' as the Germans call them, represented in our modern world only by the curious and exceptional Burramunda of Australia, and the mud lishes of Africa and South America,^ creatures which show, as do some of the mailed fishes, or ganoids, of equally great age, the intermediate stages between a swimming bladder and a lung, and thus ap- proach nearer to the air-breathing animals than any other fishes. Many years ago, in " Acadian Geology," I referred to the probability that the mailed and lung fishes of the Devonian and Carboniferous possessed airb ladders so constructed as to ena Die them to breatne air, as is the case with their modern representatives. In the modern species this, no doubt, enables them to haunt badly aerated waters, in swamps and sluggish streams, and in some cases even to survive when the water in which they live is dried up. In the Carboniferous and Devonian it may have served a similar purpose, fitting them to inhabit the lagoons and creeks of the coal swamps, the water of which must often have been badly aerated. It makes against this that some sharks follov/ed them into these waters, * By Mr. F. D. Adams and Dr. Walcotf. * Cciatodus, Lipidosiren, Protoptenis. I ale tlie s I can ale the /onian. speci- nost as ve un- of the which fishes : types emark- ■scnted ptional :a and of the lediate ms ap- fishes. to the in and as to lodern nables Liggish water s and them )s, the makes ^'aters, '^^''^^'^rrnffmiimmmii «HPH \h r*'-^ gaaaflfiijflrj^ ^'^^ '0(f, % ^OooaoBBm #}, r- h Two rRiMiriViC ViiRiEBRATFS, PahcospoiUylus (enlarged) and Ph'richthus ( red need ) , (After Woodward, with some modifications.) THE SUCCESSION OF ANIMAL FORMS 185 and the modem sharks have no swim-bladders. Possibly, however, the sharks habitually haunted the open sea, and only made occasional raids on the dangerous waters tenanted by the ganoids. It is also true that only certain genera of sharks are found to be represented in the carbonaceous shales, and they may have differed in this respect from the ordinary forms of the order. It has been suggested that only a small change would be necessary to enable some of these lung fishes to become Batrachians, and no doubt this is the nearest approach of the fish to the reptile ; but we have not yet found connecting links sufficient to bridge over the whole distance. The plate-bearing ganoids of the Silurian and Devonian, at one time supposed to be allied to Crustaceans, but whose dignity as " Forerur^ners of the back-boned animals " is now generally admitted,^ are clearly true fishes, and of somewhat high rank, their strange bony armour being evidently a special protection against the attacks of contemporary sharks and gigantic crustaceans ; and if we may judge by the Colorado specimens, their existence dates back almost to the close of the Cambrian, and they were probably contemporary with small sharks; while as early as the Silurian and Devonian, if we regard the scaly ganoids as a distinct type, we have already four types of fishes, and these akin to those which in modern time we must regard as the highest of their class. One very little fish of the Devonian, of which specimens have been kindly sent me by a friend in Scotland,^ the Pala;o- H * A. Smith Woodward, "Natural Science," 1S92, and Annals and Afaga. Nal, Hist., October, 1890. This able naturalist, in introihicing his subject, remarks, from the point of view of an evolutionist : — "Whether some form of 'worm' gave origin to the forerunners of the great bank-boned race, or whether a primeval relative of the King-crab turned upside down and rearranged limbs and head — these are questions still admitting of endless discussion, no doul)t fruitless in their main object, but desirable from the new lines of investigation they continually suggest."' - James Reed, Esq., of Allan House, Blairgowrie. T UK .1' u 1 86 THE SUCCESSION OF ANIMAL FORMS «it Ml ft . i spondylus of Traquair, may raise still higher hopes for the early vertebrates. It is a little creature, an inch to two inches in length, destitute or nearly destitute of bony covering, having a head which suggests the presence of external gills, large eyes, and even elongated nasal bones, ^ a long vertebral column composed of separate bony ri>igs, more than fifty in number, with possible indications of nbs in front and distinct neural and haemal processes behind. One cannot look at it with- out the suggestion occurring of some of the smaller snake- like Batrachians of the Carboniferous and Permian ; and I should not be surprised if it should come to be regarded either as a forerunner of the Batrachians or as a primitive tadpole. However this may be, the upper part of the Devon :n, though rich in fishes and plants, has afforded no higher vertebrates than its lower parts, and in the lowest Carboniferous beds we suddenly find ourselves in the presence of Batrachians with well-developed limbs and characters which ally them to the Lizards. True lizard-like reptiles appear in the Permian, and then we enter on that marvellous reign of reptiles, in which this class assumed so many great and remarkable forms, and asserted itself in a manner of which the now degraded reptilian class can afford no conception. The mammals and birds make their first appearance quietly in small and humble forms in the reign of reptiles, in which there was little place left for them by the latter ; but the mammals burst upon us in all their number and magnitude in the Eocene and Miocene, in which quadrupedal mammalian life may be said to have culminated in grandeur, variety, and geographical distribution ; far excelling in these respects the time in which we live. The development in time of the back-boned animals thus stands in some degree by itself; but it illustrates the same ' I am aware that Woodward regards these parts differently. THE SUCCESSION OF ANIMAL FORMS 187 laws of early generalised types, and sudden and wide introduc- tion of new forms, which we have seen in the case of the in- vertebrates and the plants. Such facts as those to which I have referred, and many others, which want of space prevents me from noticing, are in one respect eminently unsatisfactory, for they show us how difficult must be any attempts to explain the origin and succes- sion of life. For this reason they are quietly put aside or explained away in most of the current hypotheses on the sub- ject. But we must, as men of science, face these difficulties, and be content to search for facts and laws, even if they should prove fatal to preconceived views. A group of new laws, indeed, here breaks upon us. (i) The great vitality and rapid extension and variation of new specific types. (2) The law of spontaneous decay and mor- tality of species in time. (3) The law of periodicity and of simultaneous appearance of many allied forms. (4) The abrupt entrance and slow decay of groups of species. (5) The extremely long duration of some species in time. (6) The grand march of new forms landwards, and upwards in rank. Such general truths deeply impress us at least with the conclu- sion that we are tracing, not a fortuitous succession, but the action of po^v'er working by law. I have thus far said nothing of the bearing of the prevalent ideas of descent with modification on this wonderful pro- cession of life. None of these, of course, can be expected to take us back to the origin of living beings ; but they also fail J explain* why so vast numbers of highly organized species struggle into existence simultaneously in one age and disappear in another, why no continuous chain of succession in time can be found gradually blending species into each other, and why, in the natural succession of things, degradation under the influence of external conditions and final extinction seem to be laws of organic existence. It is useless here to appeal to the r ■5!" ;'.i i88 THE SUCCESSION OF ANIMAL FORMS ir I ; imperfection of tlie record, or to the movements or migrations of species. Tlie record is now, in many important parts, too complete, and the 'simultaneousness of the entrance of the faunas and floras too certainly established, and moving species from place to place only evades the difficulty. The truth is that such hypotheses are at present premature, and that we require to have larger collections of facts. Independently of this, however, it appears to me that from a philosophical point of view it is extremely probable that all theories of evolution, as at present applied to life, are fundamentally defective in being too partial in their character; and perhaps I cannot better group the remainder of the facts to which I wish to refer than by using them to illustrate this feature of most of our attempts at generalization on this subject. First, then, these hypotheses are too partial, in their tendency to refer numerous and complex phenomena to one cause, or to a few causes only, when all trustworthy analogy would indicate that they must result from many concurrent forces and deter- minations of force. We have all, no doubt, read those ingenious, not to say amusing, speculations in which some entomologists and botanists have indulged with reference to the mutual relations of flowers and suctorial insects. Geologically the facts oblige us to begin with Cryptogamous plants and chewing insects, and out of the desire of insects for non-existent honey, and the adaptations of plants to the requirements of non- existent suctorial apparatus, we have to evolve the marvellous complexity of floral form and colouring, and the exquisitely delicate apparatus of the mouths of haustellate insects. Now, when it is borne in mind that this theory implies a mental con- fusion on our part precisely similar to that which, in the depart- ment of mechanics, actuates the seekers for perpetual motion, that we have not the smallest tittle of evidence that the changes required have actually occurred in any one case, and that the thousands of other structures and relations of the plant and the i*U THE SUCCESSION OF ANIMAL FORMS 189 insect have to be worked out by a series of concurrent develop- ments GO complex and absolutely incalculable in the aggregate, that the cycles and epicycles of the Ptolemaic astronomy were child's play in comparison, we need not wonder that the com- mon sense of mankind revolts against such fancies, and that we are accused of attempting to construct the universe by methods that would baffle Omnipotence itself, because they are simply absurd. In this aspect of them, indeed, such speculations are necessarily futile, because no mind can grasp all the com- plexities of even any one case, and it is useless to follow out an imaginary line of development which unexplained facts must contradict at every step. This is also, no doubt, the reason why all recent attempts at constructing " Phylogenies " are so changeable, and why no two experts can agree about almost any of them. A second aspect in which such speculations are too partial, is in the unwarranted use which they make of analogy. It is not unusual to find such analogies as that between the em- bryonic development of the individual animal and the succes- sion of animals in geological time placed on a level with that reasoning from analogy by which geologists apply modern causes to explain geological formations. No claim could be more unfounded. When the geologist studies ancient lime- stones built up of the remains of corals, and then applies the phenomena of modern coral reef? to explain their origin, he brings the latter to bear on the former by an analogy which in- cludes not merely the rpparent results, but the causes at work, and the conditions of their action, and it is on this that the validity of his comparison depends, in so far as it relates to similarity of mode of formation. But when we compare the development of an animal from an embryo cell with the pro- gress of animals in time, though we have a curious analogy as to the steps of the process, the conditions and causes at work are known to be altogether dissimilar, and therefore we have no fpr^ r.'^A^-y/jrj .■ I -J 190 THE SUCCESSION OF ANIMAL FORMS 1 i i f 1! •/ 1/ 11 I evidence whatever as to identity of cause, and our reasoning becomes at once the most transparent of fallacies. Further, we have no right here to overlook the fact that the conditions of the embryo are determined by those of c. previous adult, and that no sooner does this hereditary potentiality produce a new adult animal, than the terrible external agencies of the physical world, in presence of which all life exists, begin to tell on the organism, and after a struggle of longer or shorter duration it succumbs to death, and its substance returns into inorganic nature, a law from which even the longer life of the species does not seem to exempt it. All this is so plain and manifest that it is extraordinary that evolutionists will continue to use such partial and imperfect arguments. Another illustration may be taken from that application of the doctrine of natural selection to explain the introduction of species in geological time, which is so elaborately discussed by Sir C. Lyell in the last edition of his " Principles of Geology." The great geolo- gist evidently leans strongly to the theory, and claims for it the " highest degree of probability," yet he perceives that there is a serious gap in it ; since no modern fact has ever proved the origin of a new species by modification. Such a gap, if it existed in those grand analogies by which he explained geo- logical formations through modern causes, would be admitted to be fatal. A third illustration of the partial character of these hypo- theses may be taken from the use made of the theory deduced from modern physical discoveries, that life must be merely a product of the continuous operation of physical laws. The assumption — for it is nothing more — that the phenomena of life are produced merely by some arrangement of physical forces, even if it be admitted to be true, gives only a partial explana- tion of the possible origin of life. It does not account for the fact that life, as a force, or combination of forces, is set in antagonism to all other forces. It does not account for the THE SUCCESSTON OF ANIMAL FORMS 191 y a rhe llifc 'es, |na- the in the marvellous connection of life with organization. It does not account for the determination and arrangement of forces implied in life. A very simple illustration may make this plain. If the problem to be solved were the origin of the mariner's compass, one might assert that it is wholly a physical arrangement, both as to matter and force. Another might assert that it involves mind and intelligence in addition. In some sense both would be right. The properties of magnetic force and of iron or steel are purely physical, and it might even be within the bounds of possibility that sc ■"^'where in the universe a mass of natural loadstone may have been so balanced as to swing in harmony with the earth's magnetism. Yet we would surely be regarded as very credulous if we could be in- duced to believe that the mariner's compass has originated in that way. This argument applies with a thousandfold greater force to the origin of life, which involves even in its simplest forms so many more adjustments of force and so much more complex machinery. Fourthly, these hypotheses are partial, inasmuch as they fail to account for the vastly varied and correlated interdepen- dencies of natural things and forces, and for the unity of plan which pervades the whole. These can be explained only by taking into the account another element from without. Even when it professes to admit the existence of a God, ^he evolu- tionist reasoning of our day contents itself altogether with the physical or visible universe, and leaves entirely out of sight the power of the unseen and spiritual, as if this were something with which science has nothing to do, but which belongs only to imagination or sentiment. So much has this been the case, that when recently a few physicists and naturalists have referred to the " Unseen Universe," they have seemed to be teaching new and startling truths, though only reviving some of the oldest and most permanent ideas of our race. From the dawn of human thought it has been the conclusion ahke of philoso- 'U H '?♦! rmitnal London Geological Society ^ vol, xxviii. 2IO THE GENESIS AND MIGRATIONS OF PLANTS 1. !,!■' 'J , f coal formation, the floras of the Lower Carboniferous (Sub- carboniferous of some American geologists) and the Millstone Grit, and in a report upon these ^ similar deductions were ex- pressed. It was stated that in Newfoundland and Northern Cape Breton the coal formation species come in at an early part of that period, and as we proceed southward they belong to progressively newer portions of the Carboniferous system. The same fact is observed in the coal l)eds of Scotland, as compared with '' ose of England, and it indicates that the coal formation flora, like that of the Devonian, spread itself from the north, and this accords with the somewhat extensive occurrence of Lower Carboniferous rocks and fossils in the Parry Islands and elsewhere in the Arctic regions.^ Passing over the comparatively poor flora of the earlier Mesozoic, consisting largely of cycads, pines, and ferns, which, as we have seen, is probably of southern origin, and is as yet little known in the arctic, though represented, according to Heer, by the supposed Jurassic flora of Cape Boheman, we find, especially at Kome and Atane in Greenland, an interest- ing occurrence of those earliest precursors of the truly modern forms of plants which appear in the Cretaceous, the period of the English chalk, and of the New Jersey greensands. There are two plant groups of this age in Greenland, one, that of Kome consists almost entirely of ferns, cycads, and pines, and is of decidedly Mesozoic aspect. This was regarded by Heer as Lower Cretaceous. The other, that of Atane, holds remains of many modern temperate genera, as Popidus^ Myrica, Ficiis^ Sassafras^ and Magnolia. This he regards as Middle Creta- ceous. Above this is the Patoot series, with many exogenous trees of modern genera, and representing the Upper Creta- ceous. Resting upon these Upper Cretaceous beds, without I 1 '» \ * " Fossil Plants of Lower Carboniferous and Millstone Grit Formations of Canada," pp. 47, 10 plates. Montreal, 1873. * G. M. Dawson, '* Report on Arctic Regions of Canada." _._^>^. * ■^- --I i'THftalMl THE GENESIS AND MIGRATIONS OF PLANTS 211 the intervention of any other formation,^ are beds rich in plants of much more modern appearance, and referred by Heer to the Miocene period, a reference which appeared at the time to be warranted by comparison with the Tertiary plants of Europe, but, as we shall see, not with those of America. Still farther north this so-called Miocene assemblage of plants appears in Spitzbergen and Grinnell Land ; but there, owing to the predominance of trees allied to the spruces, it has a decidedly more boreal character than in (ireenland, as might be anticipated from its nearer approach to the pole."' If now we turn to the Cretaceous and Tertiary floras of Western America, as described by Lesquereux, Newberry, and AVard, we fmd in the lowest Cretaceous rocks known there until very recently — those of the Dakota group, which may be in the lower part of the Middle Cretaceous — a series of plants '^ essentially similar to those of the Middle Cretaceous of Greenland. To these I have been able to add, through the researches of Mr. Richardson and Dr. G. M. Dawson, a still earlier flora, that of the Kootanie and Queen Charlotte Island formations, as old as the Gault and Wealden. It v.ants the broad-leaved plants of the Dakota, and consists mainly of pines, cycads, and ferns ; and only in its upper part contains a few forerunners of the exogens.*^ These plants occur in beds indicating shallow sea conditions as prevalent in the interior of America, causing, no doubt, a warm climate in the north. Overlying this plant-bearing formation we have an oceanic limestone (the Niobrara), corres})onding in many respects to * Nordenskiold, Expedition to Greenland, Gcologicul Auigaziiw, 1872. " Yet even here the Bald Cypress [Taxoditiin dislichtiin), or a tree nearly al'ed to it, is found, though this species is now limited to the Soutliern States. Fielden and Ue \<.:Kncc, Journal 0/ Gtvlogical Socic/y, 1878. ^ Lesquereux, Rejiort on Cretaceous Flora. The reader not interested in American details may pass over to the middle of page :?I3. * This flora has since been described in Virginia and Maryland ])y Fontaine, and has been recognised in Montana by Newberry. ■||l f m ;K I >', '■ f r 212 THE GENESIS AND MIGRATIONS OF PLANTS the European chalk, and containing similar microscopic organ- isms. This extends far north into the British territory,^ indi- cating farther subsidence and the prevalence of a vast Mediter- ranean Sea, filled with warm water from the equatorial cur- rents, and not invaded by cold waters from the north. This is succeeded by Upper Cretaceous deposits of clay and sand- stone, with marine remains, though very sparsely distributed ; and these show that further subsidence or denudation in the north had opened a way for the arctic currents, producing a fall of temperature at the close of the Cretaceous, and partially filling up the Mediterranean of that period. Of the flora of the Middle and Upper Cretaceous periods, which must have been very long, we know something in the interior regions through the plants of Dunvegan and Peace River ; ^ and on the coast of British Columbia we have the remarkable Cretaceous coalfield of Vancouver's Island, which holds the remains of plants of modern genera, including species of fan palm, ginkgo, evergreen oak, tulip tree, and other forms proper to a warm temperature or subtropical climate. They probably indicate a warmer climate as then prevalent on the Pacific coast than in the interior, and in this respect corre- spond with a meagre transition flora, intermediate between the Cretaceous and Eocene or earliest Tertiary of the interior re- gions, and named by Lesquereux the Lower Lignitic. Immediately above these Upper Cretaceous beds we have the great Lignite Tertiary of the west — the Laramie group oi recent American reports ^ — abounding in fossil plants, proper to a temperate climate, at one time regarded as Miocene, but now known to be Lower Eocene.*^ These beds, with their * G. M. Dawson, Report on Forty-ninth Parallel. 2 Trans. Royal Society of Canada. ^ Ward, Repts. and Bulletins Am. Geol. Survey. ■* Lesquereux's Tertiary Flora; White and Ward on the Laramie Group; Stevenson, Geological Relations of Lignitic CJroups, Am. Phil. SocTune, 1875. Ml I II iiii«iiTirinri'iii7'in''ard the arctic regions. The flora Avhich succeeds this in the sec- tions at Atane and Patoot has no special affinities with the southern hemisphere, and is of a warm, temperate and conti- nental character. It is very similar in its general aspect to that of the Dakota group farther to the south, and this is probably Middle Cretaceous. This flora must have originated either soniewhere in temperate America, or within the arctic circle, and it must have replaced the older one by virtue of increasing subsidence and gradual change of climate. It must therefore have been connected with the depression of the land which took i)lace in the course of the Cretaceous. During this movement it spread over all Western America, and as the land again arose from the sea of the Niobrara chalk, it assumed an aspect more suited to a cool climate, or moved southward, * Reports Geological Survey of Canadn. "^ Fontaine has well described the Mcsozoic flora of Virginia, AiiieHcan fotinial of Science, January, 1879. ■■ THE GENESIS AND MIGRATIONS OF PLANTS 21 5 and finally abandoned the Arctic regions, perhaps continuing to exist on the Pacific coast, and in sheltered places in the north, till the warm inland seas of the Upper Cretaceous had given place to the wide plains and landlocked brackish seas or fresh-water lakes of the Laramie period (Eocene). Thus the true Upper Cretaceous marks in the interior a cooler period intervening between the Middle Cretaceous and the Lower Eocene floras of (ireenland. This latter established itself in Greenland, and probably all around the Arctic circle, in the mild period of the earliest Eocene, and as the climate le northern hemisphere became gradually reduced from that time till the end of the Pliocene, it marched on over both r ■ ^.tinents to the southward, chased beh'nd by the modern arctic flora, and eventually by the frost and snow of the v .jxial age. This history may admit of cor- rection in details ; but, so far as present knowledge extends, it is in the main not far from the truth. Perhaps the first great question which it raises is that as to the causes of the alternations of warm and cold climates in the north, apparently demanded by the vicissitudes of the vegetable kingdom. Here we may set aside the idea that in former times plants were suited to endure greater cold than at present. It is true that some of the fossil Greenland plants are of un- known genera, and many are new species to us ; but we are on the whole safe in affirming that they must have required conditions simih.r to those necessary to their n^odern repre- sentatives, except within such limits as we now find to hold in similar cases among existing plants. Still we know that at the present time many species found in the equable climate of England will not live in Canada, though species to all appear- ance similar in structure are natives of the latter. There is also some reason to suppose that species, when new, may have greater hardiness and adaptability than when in old age, and verging toward extinction. In any case, these facts can account Wf ?/■ ) I'l 2l6 THE GENESIS AND MIGRATIONS OF PLANTS flV :1 for but a small part of the phenomena, which require to be ex- plained by physical changes affecting the earth as a whole, or at least the northern hemisphere. Many theoretical views have been suggested on this subject, which will be found dis- cussed elsewhere, and perhaps the most practical way to deal with them here will be to refer to the actual conditions known to have prevailed in connection with the introduction and distribution of the principal floras which have succeeded each other in geological history. If we can assume that all the carbon now sealed up in lime- stones and in coal was originally floating in the atmosphere as carbon dioxide, then wo would have a cause which might seriously have affected the earlier land floras — that, for instance, which may have existed in the Eozoic age, and those well known to us in the Palceozoic. Such an excess of carbonic acid would have required some difference of constitution in the plants themselves ; it would have afi'orded them a super- abundance of wood-forming nutriment, and it would have acted as an obstacle to the radiation of heat from the earth, almost equal to the glass roof of a greenhouse, thus constituting a great corrective of changes of temperature. Under such cir- cumstances we might expect a peculiar and exuberant vegeta- tion in the earlier geological ages, though this would not apply to the later in any appreciable degree. In addition to this we know that the geographical arrangements of our continents were suited to the production of a great uniformity of climate. Taking the American continent as the simpler, we know that in this period there existed in the interior plateau between the rudimentary eastern and western mountains a great inland sea, so sheltered from the north that its waters contained hun- dreds of species of corals, growing with a luxuriance unsur- passed in the modern tropics. On the shores and islands of such a sea we do not wonder that there should have been tree ferns and gigantic lycopods. In the succeeding Carboniferous, KMi • .* •-. m> -M-H-^ •— *« *'M . THE GENESIS AND MIGRATIONS OF PLANTS 21/ vast areas, both on the margins and in the interior of the continent, were occupied with swampy flats and lagoons, the atmosphere of which must have been loaded with vapour, and ich in compounds of carbon, though the temperature may have been lower than in the Devonian. There still remained, however, more especially in the west, a remnant of the old inland sea, which must have greatly aided in carrying a warm temperature to the north. If now we pass to the succeeding Jurassic age, we find a more meagre and less widely distributed flora, corresponding to less favourable geographical and climatal conditions, while in the Cretaceous and Eocene ages a return to the old con- dition of a warm Mediterranean in continuation of the Gulf of Mexico gave those facilities for vegetable growth, which carried plants of the temperate zone as far north as Greenland. It thus appears that those changes of physical geography and of the ocean currents to which reference is so often made in these papers, apply to the question of the distribution or plants in geological time. These same causes may help us to deal with the peculiarities of the great (ilacial age, which may have been rendered ex- ceptionally severe by the combination of several of the conti- nental and oceanic causes of refrigeration. We must not imagine, however, that the views of those extreme glacialists, who suppose continental ice caps reaching half way to the equator, are borne out by facts. In truth, the ice accumulat- ing round the pole must have been surrounded by water, and there must have been tree-clad islands in the midst of the icy seas, even in the time of greatest refrigeration. This is proved by the fact that in the lower Leda clay of Eastern Canada, which belongs to the time of greatest submergence, and whose fossil shells show sea water almost at the freezing point, there are leaves of poplars and other plants which must have been drifted from neighbouring shores. Similar remains occur in if: m ^ mmm N' mm II I i'i: ! if- n ^1 I! i 2l8 THE GENESIS AND MIGRATIONS OF PLANTS clays of similar origin in the basin of the great lakes and in the West, and are not Arctic plants, but members of the North Temperate flora.^ These have been called " interglacial," but there is no evidence to prove that they are not truly glacial. Thus, while the arctic flora must have continued to exist within the Arctic circle in the Glacial age, we have evidence that those of the cold temperate and subarctic zones continued to exist pretty far north. At the same time the warm temperate flora would be driven to the south, excent where sustained in insular spots warmed by the equatorial currents. It would return north- ward on the re-elevation of the land and the return of warmth. If, however, our modern flora is thus one that has returned from the south, this would account for its poverty in species as compared with those of the early Tertiary. Groups of plants descending from the north have been rich and varied. Re- turning from the south they are like the shattered remains of a beaten army. This, at least, has been the case with such re- treating floras as those of the Lower Carboniferous, the Per- mian, and the Jurassic, and possibly that of the Lower Eocene of Europe. The question of the supply of light to an Arctic flora is much less difticult than some have imagined. The long summer day is in this respect a good substitute for a longer season of growth, while a copious covering of winter snow not only protects evergreen plants from those sudden alternations of temperature which are more destructive than intense frost, and prevents the frost from penetrating to their roots, but by the ammonia which it absorbs preserves their greenness. According to Dr. Brown, the Danish ladies of Disco long ago solved this problem. ^ He informs us that they cultivate in * Pleistocene Plants of Cannda, Dawson and Pcnhallow, Bu//. Geo/. Socj'., America, 1890. In Europe the Arctic flora extended, relatively to present climate, farther south. ^ Florula Discoana, Botanical Society of Edinburgh, 1868. THE GENESIS AND MIGRATIONS OF PLANTS 219 their houses most of our garden flowers, as roses, fuchsias, and geranium;;, showing that it is merely warmth, and not light that is required to enable a subtropical flora to thrive in Green- land. Even in Canada, which has a flora richer in some re- spects than that of temperate Europe, growth is effectually arrested by cold for nearly six months, and though there is ample sunlight there is no vegetation. It is indeed not im- possible that in the plans of the Creator the continuous summer s n of the Arctic regions may have been made the means for the introduction, or at least for the rapid growth and multiplication, of new and more varied types of plants. It is a matter of familiar observation in Canada that our hardy garden flowers attain to a greater luxuriance and intensity of colour in those more northern latitudes where they have the advan- tage of long and sunny summer days. Much, of course, remains to be known of the history of the old floras whose fortunes I have endeavoured to sketch, and which seem to have been driven like shuttlecocks from north to south, and from south to north, especially on the American continent, whose meridional extension seems to have given a field specially suited for such operations. This great stretch of the western continent from north to south is also connected with the interesting fact that, when new floras are entering from the Arctic regions, they appear earlier in America than in Europe ; and that in times when the old floras are retreating from the south, old genera and species linger longer in America. Thus, in the Devonian and Cre- taceous new forms of those periods appear in America long before they are recognised in Europe, and in the modern epoch forms that would be regarded in Europe as Mioccne still exist. Much confusion in reasoning as to the geological ages of the fossil flora has arisen from want of attention to this circumstance. What we have learned respecting this wonderful history has ms^fmm^ «■ ri 220 THE GENESIS AND MIGRATIONS OF PLANTS if- I served strangely to change some of our preconc