UC-NRLF B 3 T25 flflfl THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PROF. CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID EARTH SCIENCES LIBRARY s <^ t (->'! * w P H ^* P4 M LIFE'S DAWN ON EARTH BEING THE AND THEIR RELATIONS TO GEOLOGICAL TIME AND TO THE DEVELOPMENT OF THE ANIMAL KINGDOM. BT J. W. DAWSON, LL.D., F.R.S., F.G.S., ETC., PRINCIPAL AND~"VlCE-CHANCELLOR OF M'GILL UNIVERSITY, MONTREAL AUTHOR OF "ARCHAIA," "ACADIAN GEOLOGY," "THE STORY OF THE EARTH AND MAN," ETC. SECOND THOUSAND. LONDON : HODDER & STOUGHTON, 27, PATERNOSTER ROW. MDCCGLXXV. Butler & Tanner, Th Selwood Printing Works, Frome, and London. EARTH SCIENCES UBRARY 0f SIR WILLIAM EDMOND LOGAN, LL.D., F.R.S., F.G.S., THIS WORK IS DEDICATED, Not merely as a fitting acknowledgment of his long and successful labours in the geology of those most ancient rocks, first named by him Laurentian, and which have afforded the earliest known traces of the beginning of life, but also as a tribute of sincere personal esteem and regard to the memory of one who, while he attained to the highest eminence as a student of nature, was also distinguished by his patriotism and public spirit, by the simplicity and earnestness of his character, and by the warmth of his friendships. "" '.' 1 PREFACE. AN eminent German geologist has characterized the discovery of fossils in the Laurentian rocks of Canada as " the opening of a new era in geological science." Believing this to be no exaggeration, I have felt it to be a duty incumbent on those who have been the apostles of this new era, to make its significance as widely known as possible to all who take any interest in scientific subjects, as well as to those naturalists and geologists who may not have had their atten- tion turned to this special topic. The delivery of occasional lectures to popular audiences on this and kindred subjects, has convinced me that the beginning of life in the earth is a theme having attractions for all intelligent persons ; while the numerous inquiries on the part of scientific students with reference to the fossils of the Eozoic age, show that the subject is yet far from being familiar to their minds. I offer no apology therefore for attempting to throw into the form of a book accessible to general readers, what is known as to Vlll PREFACE. the dawn of life, and cannot doubt that the present work will meet with at least as much acceptance as that in which I recently endeavoured to picture the whole series of the geological ages. I have to acknowledge my obligations to Sir W. E. Logan for most of the Laurentian geology in the second chapter, and also for the beautiful map which he has kindly had prepared at his own ex- pense as a contribution to the work. To Dr. Car- penter I am indebted for much information as to foraminiferal structures, and to Dr. Hunt for the chemistry of the subject. Mr. Selwyn, Director of the Geological Survey of Canada, has kindly given me access to the materials in its collections. Mr. Billings has contributed specimens and illustrations of Palaeozoic Protozoa; and Mr. Weston has aided greatly by the preparation of slices for the micro- scope, and of photographs, as well as by assistance in collecting. J. W. D. McGiLL COLLEGE, MONTREAL. April, 1875. CONTENTS. PAGE CHAPTER I. INTRODUCTORY 1 CHAPTER II. THE LAURENTIAN SYSTEM .... 7 NOTES : LOGAN ON STRUCTURE OF LAURENTIAN ; HUNT ON LIFE IN THE LAURENTIAN; LAURENTIAN GRAPHITE; WESTERN LAURENTIAN ; METAMORPHISM ... 24 CHAPTER III. THE HISTORY OF A DISCOVERY . . . 35 NOTES: LOGAN ON DISCOVERY OF EOZOON, AND ON ADDITIONAL SPECIMENS 48 CHAPTER IV. WHAT is EOZOON? 59 , NOTES: ORIGINAL DESCRIPTION; NOTE BY DR. CAR- PENTER ; SPECIMENS FROM LONG LAKE ; ADDITIONAL STRUCTURAL FACTS 76 CHAPTER V. PRESERVATION OF EOZOON .... 93 NOTES: HUNT ON MINERALOGY OF EOZOON; SILICI- FIED FOSSILS IN SILURIAN LIMESTONES; MINERALS ASSOCIATED WITH EOZOON ; GLAUCONITES . . . 115 CHAPTER VI. CONTEMPORARIES AND SUCCESSORS . . 127 NOTES : ON STROMATOPORID^ ; LOCALITIES OF EOZOON 165 CHAPTER VII. OPPONENTS AND OBJECTIONS . ; . 109 NOTES: OBJECTIONS AND EEPLIES; HUNT ON CHEMICAL OBJECTIONS ; REPLY BY DR. CARPENTER 184 CHAPTER VIII. THE DAWN-ANIMAL AS A TEACHER IN SCIENCE 207 APPENDIX . . 235 INDEX . 237 LIST OF ILLUSTEATIONS. FULL PAGE ILLUSTRATIONS. TO FACE PAGK I. CAPE TRINITY, FROM: A PHOTOGRAPH (Frontispiece). II. MAP OF THE LAURENTIAN EEGION ON THE RIVER OTTAWA 7 III. WEATHERED SPECIMEN OF EOZOON, FROM A PHOTOGRAPH 35 IV. RESTORATION OF EOZOON . ' . ' -'. ' ' . . .59 V. NATURE -PRINT OF EOZOON " . ' . . . .93 VI. CANALS OF EOZOON, MAGNIFIED, FROM PHOTOGRAPHS 127 VII. NATURE -PRINT OF LARGE LAMINATED SPECIMEN . 169 VIII. EOZOON WITH CHRYSOTILE, ETC. .... 207 WOODCUTS. FIG- PAGE 1. GENERAL 'SECTION 9 2. LAURENTIAN HILLS 11 3. SECTION OF LAURENTIAN . .,.,,. . . 13 4. LAURENTIAN MAP . . .. .'.... . . 16 5. SECTION AT ST. PIERRE . . . . . .22 6. SKETCH OF ROCKS AT ST. PIERRE . , . .22 7. EOZOON FROM BURGESS 36 8. 9. EOZOON FROM CALUMET 39 10. CANALS OF EOZOON 41 11. NUMMULINE WALL 43 12. AM(EBA 60 13. ACTINOPHRYS. . 60 Xll LIST OP ILLUSTRATIONS. FIG. PAGE 14. ENTOSOLENIA 62 15. BILOCULINA 62 16. POLYSTOMELLA 62 17. POLYMORPHINA . . 63 18. ARCH^EOSPHERIN^E . . . . v . . . 67 19. NUMMULITES . . .73 20. CALCARINA . . . .' - - . ..... . 73 21. FORAMINIFERAL ROCK-BUILDERS 75 21a. CASTS OF CELLS. OF EOZOON hi, . . . .92 22. MODES OP MINERALIZATION . . . . ' . .96 23. SILURIAN ORGANIC LIMESTONE ..... 98 24. WALL OF EOZOON PENETRATED WITH CANALS . . 98 25. CRINOID INFILTRATED WITH SILICATE .... 103 26. SHELL INFILTRATED WITH SILICATE . . . .104 27. DIAGRAM OF PROPER WALL, ETC 106 28. 29. CASTS OF CANALS 107 30. EOZOON FROM TUDOR Ill 31. ACERVULINE VARIETY OF EOZOON 135 32. 33, 34. ARCH^OSPHERIN^B 137, 138 35. ANNELID BURROWS 140 36. ARCH^EOSPHERIN^ 148 37. EozooN BAVARICUM 149 38. 39, 40. ARCH^EOCYATHUS ..... 152, 153 41. ARCH^OCYATHUS (STRUCTURE OF) 154 42. STROMATOPORA 157 43. STROMATOPORA (STRUCTURE OF) 158 44. CAUNOPORA 159 45. CCENOSTROMA 160 46. EECEPTACULITES 162 47, 48. EECEPTACULITES (STRUCTURE OF) . . . . 163 49. LAMINAE OF EOZOON 176 THE DAWN OF LIFE, CHAPTER I. INTRODUCTORY. EVERY one lias heard of, or ought to have heard of, Eozoon Canadense, the Canadian Dawn-animal, the sole fossil of the ancient Laurentian rocks of North America, the earliest known representative on our planet of those wondrous powers of animal life which culminate and unite themselves with the spirit- world in man himself. Yet few even of those to whom the name is familiar, know how much it implies, and how strange and wonderful is the story which can be evoked from this first-born of old ocean. No one probably believes that animal life has been an eternal succession of like forms of being. We are familiar with the idea that in some way it was intro- duced; and most men now know, either from the testimony of Genesis or geology, or of both, that the lower forms of animal life were introduced first, and that these first living creatures had their birth in the waters, which are still the prolific mother of living things innumerable. Further, there is a general im- pression that it would be the most appropriate way that the great procession of animal existence should B 2 THE DAWN OF LIFE. commence with the humblest types known to us, and should march on in successive bands of gradually increasing dignity and power, till man himself brings up the rear. Do we know the first animal ? Can we name it, explain its structure, and state its relations to its suc- cessors ? Can we do this by inference from the suc- ceeding 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 which 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 them- selves 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 Egyptian for his sacred animals would be a comparatively reason- able idolatry, if we could imagine any of these animals to have been the first that emerged from the domain of dead matter, and the first link in a reproductive INTRODUCTORY. O chain o being that produced all the population of the world. Independently of any such hypotheses, all students of nature must regard with surpassing in- terest the first bright streaks of light that break on the long reign of primeval night and death, and pre- sage 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 desti- tute 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 Azoic formations, afforded forms believed to be of organic origin. The discovery was hailed with enthusiasm by those who had been prepared by previous study to re- ceive 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 con- fined to scientific transactions and periodicals, read by very few except specialists. Thus, few even of geo- logical and biological students have clear ideas of the real nature and mode of occurrence of these ancient organisms, and of their relations to better known forms of life ; while the crudest and most inaccurate 4 THE DAWN OF LIFE. ideas have been current in lectures and popular books^ and even in text-books, although to the minds of those really acquainted with the facts, all the disputed points have long ago been satisfactorily settled, and the true nature and affinities of Eozoon are distinctly and satisfactorily understood. 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 ani- mal existence; but it is for us at present the last organic foothold, on which we can poise ourselves, that we may look back into the abyss of the infinite past, and forward to the long and varied progress of life in geological time. Its consideration, therefore, is cer- tain, if properly entered into, to be fruitful of interest- ing and valuable thought, and to form the best possible introduction to the history of life in connection with geology. It is for these reasons, and because I have been connected with this great discovery from the first, and have for the last ten years given to it an amount of labour and attention far greater than could be ade- quately represented by short and technical papers, that I have planned the present work. In it I propose to give a popular, yet as far as possible accurate, ac- count of all that is known of the Dawn-animal of the Laurentian rocks of Canada. This will include, firstly: a descriptive notice of the Laurentian formation itself. INTRODUCTORY. Secondly : a history of the steps which led to the discovery and proper interpretation of this ancient fossil. Thirdly : the description of Eozoon, and the explanation of the manner in which its remains have been preserved. Fourthly: inquiries as to forms of animal life, its contemporaries and immediate succes- sors, or allied to it by zoological affinity. Fifthly: the objections which have been urged against its organic nature. And sixthly : the summing up of the lessons in science which it is fitted to teach. On these points, while I shall endeavour to state the substance of all that Las been previously published, I shall bring forward many new facts illustrative of points hitherto more or less obscure, and shall endeavour so to picture these in themselves and their relations, as to give distinct and vivid impressions to the reader. For the benefit of those who may not have access to the original memoirs, or may not have time to consult them, I shall append to the several chapters some of the technical details. These may be omitted by the general reader ; but will serve to make the work more complete and useful as a book of reference. The only preparation necessary for the unscientific reader of this work, will be some little knowledge of the division of geological time into successive ages, as represented by the diagram of formations appended to this chapter, and more full explanations may be obtained by consulting any of the numerous element- ary manuals on geology, or "The Story of the Earth and Man," by the writer of the present work. THE DAWN OF LIFE. S o 1 a 1 -S 3 OQ 03 3 1 .2 00 II o 1 "* ~ C IH O bO .2 ^ O rg e 'o S 'o Z bo ^ O ^ O X~* Q^ rK O *bfl 1-H 7 a 4 bC^ bo 1 H p4 2 O 1 h 3 1 DQ 5 1 PH ^ . P3 i v-^ DIOZOS3K OIOZCWIYd oiozoa "3.0 'QIOZONHO i 'Si i h^ 1 fe> 00 "3 S 03 a a .so cd" "^ N 5 5 . p o ^ 3 43 fl ^ 'e 1 1 I d 1 *- ^ i 11 PH ^ 5 "S CM Cj_i IM O T3 2 ^ " g IS O O rt 03 t? "3 bO bO 1 to & boO ^ c3 bO'C p II 2 'B 7; f^ " 1 o 10 THE DAWN OP LIFE. who knows that they have endured the battles and the storms of time longer than any other mountains, invests them with a dignity which their mere ele- vation would fail to give. (Fig. 2.) 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, how- ever, best displayed where they have been cut across by the great transverse gorge of the Saguenay, and where the magnificent precipices, known as Capes Trinity and Eternity, look down from their elevation of 1500 feet on a fiord, which at their base is more than 100 fathoms deep (see frontispiece). 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. 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 attractions to the agri- culturist, 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 Laurentian townships of Canada TtlE LAUEENTIAN EOCKS. 11 12 THE DAWN OF LIFE. 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 romantic 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, and similar metamorphic and crystal- line 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 she shrunk and wrinkled since those youthful days when the Laurentian rocks were her outer covering. (Fig. 3.) The elaborate sections of Sir William Logan show that these old rocks are divisible into two series, the Lower and Upper Laurentian ; the latter being the newer of the two, and perhaps separated from the former by a long interval of time ; but this Upper Laurentian being probably itself older than the Huronian series, and this again older than all the other stratified rocks. The Lower Laurentian, which attains to a thickness of more than 20,000 feet, con- sists of stratified granitic rocks or gneisses, of indu- rated sandstone or quartzite, of mica and hornblende schist, and of crystalline limestones or marbles, and iron ores, the whole interstratified with each other. The Upper Laurentian, which is 10,000 feet thick at least, consists in part of similar rocks, but associated and colours of strata often diversi- THE LAURENTIAN ROCKS. 13 with great beds of triclinic felspar, especially of that peculiar variety known as labradorite, or Labrador ^ felspar, and which sometimes by its wonderful iridescent play of colours becomes a beautiful ornamental ^ stone. ; ls I cannot describe such rocks, js but their names will tell something ^ to those who have any knowledge of the older crystalline materials '1 of the earth's crust. To those who , have not, I would advise a visit 1 to some cliff on the lower St. Law- ^ rence, or the Hebridean coasts, or o the shore of Norway, where the ^ old hard crystalline and gnarled d beds present their sharp edges to ' Z the ever raging sea, and show their endless alternations of various kinds 3 ^ 5 fied with veins and nests of crystal- line minerals. He who has seen and studied such a section of Lau- rentian rock cannot forget it. All the constituents of the Lau- . g rentian series are in that state d|^ known to geologists as metamor- ^^ phic. They were once sandstones, clays, and limestones, such as ^ 14 THE DAWN OF LIFE. the sea now deposits, or such as form the common plebeian rocks of everyday plains and hills and coast sections. Being extremely old, however, they have been buried deep in the bowels of the earth under the newer deposits, and hardened by the action of pressure and of heat and heated water. Whether this heat was part of that originally belonging to the earth when a molten mass, and still existing in its interior after aqueous rocks had begun to form on its surface, or whether it is a mere mechanical effect of the intense compression which these rocks have suffered, may be a disputed question; but the ob- servations of Sorby and of Hunt (the former in con- nection with the microscopic structure of rocks, and the latter in connection with the chemical conditions o change) show that no very excessive amount of heat would be required. These observations and those of Daubree indicate that crystallization like that of the Laurentian rocks might take place at a temperature of not over 370 of the centigrade thermometer. The study of those partial alterations which take place in the vicinity of volcanic and older aqueous masses of rock confirms these conclusions, so that we may be said to know the precise conditions under which sediments may be hardened into crystalline rocks, while the bedded character and the alterna- tions of different layers in the Laurentian rocks, as well as the indications of contemporary marine life which they contain, show that they actually are such altered sediments. (See Note D.) THE LA.URENTIAN EOCKS. 15 It is interesting to notice here that the Laurentiaii rocks thus interpreted show that the oldest known portions of our continents were formed in the waters. They are oceanic sediments deposited perhaps when there was no dry land or very little, and that little unknown to us except in so far as its debris may have entered into the composition of the Laurentian 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 pre- vious condition when the surface was heated, and the water constituted an abyss of vapours enveloping its surface, or any still earlier condition 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 principles, 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 themselves, not only with quite as great intensity, but also in the same manner, as at subsequent times. It is thus not un- likely that much of the land undergoing waste in the earlier Laurentian 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 16 THE DAWN OF LIFE. must be, unknown to us ; for it was only after the Laurentian rocks had been deposited, and after the shrinkage 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. 4 will show this, and will also show that the old Laurentian mountains mark out the future form of the American continent. FIG. 4. The Laurentian Nucleus of the American Continent. Bocks so highly altered as the Laurentian beds can scarcely be expected to hold well characterized fossil remains, and those geologists who entertained any hope that such remains might have been preserved, THE LAURENTIAN EOCKS. 17 long looked in vain for their actual discovery. Still, as astronomers have suspected the existence of un- known planets from observing perturbations not accounted for, and as voyagers have suspected the approach to unknown regions by the appearance of floating wood or stray land birds, anticipations of such discoveries have been entertained and expressed from time to time. Lyell, Dana, and Sterry Hunt more es- pecially, have committed themselves to such specula- tions. The reasons assigned may be stated thus : Assuming the Laurentian rocks to be altered sedi- ments, they must, from their great extent, have been deposited in the ocean; and if there had been no living creatures in the waters, we have no reason to believe that they would have consisted of anything more than such sandy and muddy debris as may be washed away from wasting rocks originally of igneous origin. But the Laurentian beds contain other materials than these. No formations of any geo- logical age include thicker or more extensive lime- stones. One of the beds measured by the officers of the Geological Survey, is stated to be 1500 feet in thickness, another is 1250 feet thick, and a third 750 feet; making an aggregate of 3500 feet.* These beds may be traced, with more or less interruption, for hundreds of miles. Whatever the origin of such limestones, it is plain that they indicate causes equal in extent, and comparable in power and duration, with those which have produced the greatest lime- * Logan : Geology of Canada, p. 45. C 18 THE DAWN OF LIFE. stones of the later geological periods. Now, in later formations, limestone is usually an organic rock, accu- mulated by the slow gathering from the sea-water, or its plants, of calcareous matter, by corals, f oraminifera, or shell-fish, and the deposition of their skeletons, either .entire or in fragments, in the sea-bottom. The most friable chalk and the most crystalline limestones have alike been formed in this way. We know of no reason why it should be different in the Laurentian period. When, therefore, we find great and con- formable beds of limestone, such as those described by Sir William Logan in the Laurentian of Canada, we naturally imagine a quiet sea-bottom, in which multi- tudes of animals of humble organization were accumu- lating limestone in their hard parts, and depositing this in gradually increasing thickness from age to age. Any attempts to account otherwise for these thick and greatly extended beds, regularly interstratified with other deposits, have so far been failures, and have arisen either from a want of comprehension of the nature and magnitude of the appearances to be ex- plained, or from the error of mistaking the true bedded limestones for veins of calcareous spar. The Laurentian rocks contain great quantities of carbon, in the form of graphite or plumbago. This does not occur wholly, or even principally, in veins or fissures, but in the substance of the limestone and gneiss, and in regular layers. So abundant is it, that I have estimated the amount of carbon in one division of the Lower Laurentian of the Ottawa district at an THE LAURENTIAN ROCKS. 19 aggregate thickness of not less than twenty to thirty feet, an amount comparable with that in the true coal formation itself. Now we know of no agency existing in present or in past geological time capable of deoxidizing carbonic acid, and fixing its carbon as an ingredient in permanent rocks, except vegetable life. Unless, therefore, we suppose that there existed in the Laurentian age a vast abundance of vegetation, either in the sea or on the land, we have no means of explaining the Laurentian graphite. The Laurentian formation contains great beds of oxide of iron, sometimes seventy feet in thickness. Here again we have an evidence of organic action ; for it is the deoxidizing power of vegetable matter which has in all the later formations been the efficient cause in producing bedded deposits of iron. This is the case in modern bog and lake ores, in the clay iron- stones of the coal measures, and apparently also in the great ore beds of the Silurian rocks. May not similar causes have been at work in the Laurentian period ? Any one of these reasons might, in itself, be held insufficient to prove so great and, at first sight, un- likely a conclusion as that of the existence of abundant animal and vegetable life in the Laurentian j but the concurrence of the whole in a series of deposits un- questionably marine, forms a chain of evidence so powerful that it might command belief even if no fragment of any organic and living form or structure had ever been recognised in these ancient rocks. Such was the condition of the matter until the 20 THE DAWN 01 LIFE. existence of supposed organic remains was announced by Sir W. Logan, at the American Association for the Advancement of Science, in Springfield, in 1859; and we may now proceed to narrate the manner of this discovery, and how it has been followed up. Before doing so, however, let us visit Eozoon in one of its haunts among the Laurentian Hills. One of the most noted repositories of its remains is the great Grenville band of limestone (see section, fig. 3, and map), the outcrop of which may be seen in our map of the country near the Ottawa, twisting itself like a great serpent in the midst of the gneissose rocks ; and one of the most fruitful localities is at a place called Cote St. Pierre on this band. Landing, as I did, with Mr. Weston, of the Geological Survey, last autumn, at Papineauville, we find ourselves on the Laurentian rocks, and pass over one of the great bands of gneiss for about twelve miles, to the village of St. Andre Avelin. On the road we see on either hand abrupt rocky ridges, partially clad with forest, and sometimes showing on their flanks the stratification of the gneiss in very distinct parallel bands, often contorted, as if the rocks, when soft, had been wrung as a washer- woman wrings clothes. Between the hills are little irregular valleys, from which the wheat and oats have just been reaped, and the tall Indian corn and yellow pumpkins are still standing in the fields. Where not cultivated, the land is covered with a rich second growth of young maples, birches, and oaks, among which still stand the stumps and tall scathed trunks of THE LAUEENTIAN EOCKS. 21 enormous pines, which constituted the original forest. Half way we cross the Nation Kiver, a stream nearly as large as the Tweed,, flowing placidly between wooded banks, which are mirrored in its surface ; but in the distance we can hear the roar of its rapids, dreaded by lumberers in their spring drivings of logs, and which we were told swallowed up five poor fellows only a few months ago. Arrived at St. Andre, we find a wider valley, the indication of the change to the limestone band, and along this, with the gneiss hills still in view on either hand, and often encroaching on the road, we drive for five miles more to Cote St. Pierre. At this place the lowest depression of the valley is occupied by a little pond, and, hard by, the limestone, protected by a ridge of gneiss, rises in an abrupt wooded bank by the roadside, and a little further forms a bare white promontory, projecting into the fields. Here was Mr. Lowe's original excavation, whence some of the greater blocks containing Eozoon were taken, and a larger opening made by an enter- prising American on a vein of fibrous serpentine, yielding "rock cotton," for packing steam pistons and similar purposes. (Figs. 5 and 6.) The limestone is here highly inclined and much contorted, and in all the excavations a thickness of about 100 feet of it may be exposed. It is white and crystalline, varying much however in coarseness in different bands. It is in some layers pure and white, in others it is traversed by many gray layers of gneissose and other matter, or by irregular bands and 22 THE DAWN OF LIFE. FIG. 5. Attitude of Limestone at St. Pierre. (a.) Gneiss band in the Limestone, (b.) Limestone with Eozoon. (c.) Diorite and Gneiss. FIG. 6. Gneiss and Limestone at St. Pierre, (a ) Limestone, (b ) Gneiss and Diorite. THE LAURENTIAN ROCKS. 23 nodules of pyroxene and serpentine, and it contains subordinate beds of dolomite. In one layer only, and this but a few feet thick, does the Eozoon occur in any abundance in a perfect state, though fragments and imperfectly preserved specimens abound in other parts of the bed. It is a great mistake to suppose that it constitutes whole beds of rock in an uninterrupted mass. Its true mode of occurrence is best seen on the weathered surfaces of the rock, where the serpentinous specimens project in irregular patches of various sizes, sometimes twisted by the contortion of the beds, but often too small to suffer in this way. On such surfaces the projecting patches of the fossil exhibit laminas of serpentine so precisely like the Stromatoporce of the Silurian rocks, that any collector would pounce upon them at once as fossils. In some places these small weathered specimens can be easily chipped off from the crumbling surface of the limestone ; and it is perhaps to be regretted that they have not been more extensively shown to palaeontologists, with the cut slices which to many of them are so problematical. One of the original specimens, brought from the Calumet, and now in the Museum of the Geological Survey of Canada, was of this kind, and much finer specimens from Cote St. Pierre are now in that col- lection and in my own. A very fine example is repre- sented, on a reduced scale, in Plate III., which is taken from an original photograph.* In some of the layers are found other and more minute fossils than Eozoon, * By Mr. Western, of the Geological Survey of Canada. 24 THE DAWN OP LIFE. and these, together with its fragmental remains, as ingredients in the limestone, will be discussed in the sequel. We may merely notice here that the most abundant layer of Eozoon at this place, occurs near the base of the great limestone *band, and that the upper layers in so far as seen are less rich in it. Further, there is no necessary connection between Eozoon and the occurrence of serpentine, for there are many layers full of bands and lenticular masses of that mineral without any Eozoon except occasional fragments, while the fossil is sometimes partially mineralized with pyroxene, dolomite, or common lime- stone. The section in fig. 5 will serve to show the attitude of the limestone at this place, while the more general section, fig. 3, taken from Sir William Logan, shows its relation to the other Laurentian rocks, and the sketch in fig. 6 shows its appearance as a feature on the surface of the country. NOTES TO CHAPTER II. (A.) SIR WILLIAM E. LOGAN ON THE LATJEENTIAN SYSTEM. [Journal of Geological Society of London, February, 1865. ] After stating the division of the Laurentian series into the two great groups of the Upper and Lower Laurentian, Sir William goes on to say ; "The united thickness of these two groups in Canada can- not' be less than 30,000 feet, and probably much exceeds it. The Laurentian of the west of Scotland, acording to Sir Rode- rick Murchison, also attains a great thickness. In that region the Upper Laurentian or Labrador series, has not yet been THE LAUEENTIAN EOCKS. 25 separately recognised ; but from Mr. McCulloch's description, as well as from the specimens collected by him, and now in the Museum of the Geological Society of London, it can scarcely be doubted that the Labrador series occurs in Skye. The labradorite and hypersthene rocks from that island are identical with those of the Labrador series in Canada and New York, and unlike those of any formation at any other known horizon. This resemblance did not escape the notice of Em- mons, who, in his description of the Adirondack Mountains, referred these rocks to the hypersthene rock of McCulloch, although these observers, on the opposite sides of the Atlantic, looked upon them as unstratified- In the Canadian Naturalist for 1862, Mr. Thomas Macfarlane, for some time resident in Norway, and now in Canada, drew attention to the striking resemblance between the Norwegian primitive gneiss forma- tion, as described by Naumann and Keilhau, and observed by himself, and the Laurentian, including the Labrador group ; and the equally remarkable similarity of the lower part of the primitive slate formation to the Huronian series, which is a third Canadian group. These primitive series attain a great thickness in the north of Europe, and constitute the main features of Scandinavian geology. " In Bavaria and Bohemia there is an ancient gneissic series. After the labours in Scotland, by which he was the first to establish a Laurentian equivalent in the British Isles, Sir Roderick Mtirchison, turning his attention to this central European mass, placed it on the same horizon. These rocks, underlying Barrande's Primordial zone, with a great develop- ment of intervening clay-slate, extend southward in breadth to the banks of the Danube, with a prevailing dip towards the Silurian strata. They had previously been studied by Giimbel and Crejci, who divided them into an older reddish gneiss and a newer grey gneiss. But, on the Danube, the mass which is furthest removed from the Silurian rocks being a grey gneiss, Giimbel and Crejci account for its presence by an inverted fold in the strata ; while Sir Eoderick places this at the base, and regards the whole as a single series, in the normal funda- mental position of the Laurentian of Scotland and of Canada. 26 THE DAWN OF LIFE. Considering the colossal thickness given to the series (90,000 feet), it remains to be seen whether it may not include both the Lower and Upper Laurentian, and possibly, in addition, the Huronian. " This third Canadian group (the Huronian) has been shown by my colleague, Mr. Murray, to be about 18,000 feet thick, and to consist chiefly of quartzites, slate-conglomerates, diorites, and limestones. The horizontal strata which form the base of the Lower Silurian in western Canada, rest upon the upturned edges of the Huronian series ; which, in its turn, unconformably overlies the Lower Laurentian. The Huronian is believed to be more recent than the Upper Laurentian series, although the two formations have never yet been seen in con- tact. " The united thickness of these three great series may pos- sibly far surpass that of all the succeeding rocks from the base of the Palaeozoic series to the present time. We are thus carried back to a period so far remote, that the appearance of the so-called Primordial fauna may by some be considered a comparatively modern event. We, however, find that, even during the Laurentian period, the same chemical and mechani- cal processes which have ever since been at work disintegrat- ing and reconstructing the earth's crust were in operation as now. In the conglomerates of the Huronian series there are enclosed boulders derived from the Laurentian, which seem to show that the parent rock was altered to its present crystal- line condition before the deposit of the newer formation; while interstratified with the Laurentian limestones there are beds of conglomerate, the pebbles of which are themselves rolled fragments of a still older laminated sand-rock, and the formation of these beds leads us still further into the past. " In both the Upper and Lower Laurentian series there are several zones of limestone, each of sufficient volume to consti- tute an independent formation. Of these calcareous masses it has been ascertained that three, at least, belong to the Lower Laurentian. But as we do not as yet know with cer- tainty either the base or the summit of this series, these three may be conformably followed by many more. Although the THE LAUEENTIAN EOCKS. 27 Lower and Upper Laurentian rocks spread over more than 200,000 square miles in Canada, only about 1500 square miles have yet been fully and connectedly examined in any one district, and it is still impossible to say whether the numerous exposures of Laurentian limestone met with in other parts of the province are equivalent to any of the three zones, or whether they overlie or underlie them all." (B.) DR. STERRY HUNT ON THE PROBABLE EXISTENCE OF LIFE IN THE LAURENTIAN PERIOD. Dr. Hunt's views on this subject were expressed in the American Journal of Science, [2], vol. xxxi., p. 395. From this article, written in 1861, after the announcement of the exist- ence of laminated forms supposed to be organic in the Lauren- tian, by Sir W. E. Logan, but before their structure and affinities had been ascertained, I quote the following sen- tences : " We see in the Laurentian series beds and veins of metallic sulphurets, precisely as in more recent formations ; and the extensive beds of iron ore, hundreds of feet thick, which abound in that ancient system, correspond not only to great volumes of strata deprived of that metal, but, as we may suppose, to organic matters which, but for the then great diffusion of iron-oxyd in conditions favourable for their oxi- dation, might have formed deposits of mineral carbon far more extensive than those beds of plumbago which we actually meet in the Laurentian strata. All these conditions lead us then to conclude the existence of an abundant vegetation during the Laurentian period. (C.) THE GRAPHITE OF THE LAURENTIAN. The following is from a paper by the author, in the Journal of the Geological Society, for February, 1870: " The graphite of the Laurentian of Canada occurs both in beds and in veins, and in such a manner as to show that its origin and deposition are contemporaneous with those of the 28 THE DAWN OF LIFE. containing rock. Sir William Logan states* that 'the de- posits of plumbago generally occur in the limestones or in their immediate vicinity, and granular varieties of the rock often contain large crystalline plates of plumbago. At other times this mineral is so finely disseminated as to give a bluish- gray colour to the limestone, and the distribution of bands thus coloured, seems to mark the stratification of the rock.' He further states : * The plumbago is not confined to the limestones ; large crystalline scales of it are occasionally dis- seminated in pyroxene rock or pyrallolite, and sometimes in quartzite and in feldspathic rocks, or even in magnetic oxide of iron.' In addition to these bedded forms, there are also true veins in which graphite occurs associated with calcite, quartz, orthoclase, or pyroxene, and either in disseminated scales, in detached masses, or in bands or layers ' separated from each other and from the wall rock by feldspar, pyroxene, and quartz.' Dr. Hunt also mentions the occurrence of finely granular varieties, and of that peculiarly waved and corru- gated variety simulating fossil wood, though really a mere form of laminated structure, which also occurs at Warrensburgh, New York, and at the Marinski mine in Siberia. Many of the veins are not true fissures, but rather constitute a network of shrinkage cracks or segregation veins traversing in countless numbers the containing rock, and most irregular in their dimensions, so that they often resemble strings of nodular masses. It has been supposed that the graphite of the veins was originally introduced as a liquid hydrocarbon. Dr. Hunt, however, regards ifc as possible that it may have been in a state of aqueous solution ; f but in whatever way introduced, the character of the veins indicates that in the case of the greater number of them the carbonaceous material must have been derived from the bedded rocks traversed by these veins, while there can be no doubt that the graphite found in the beds has been deposited along with the calcareous matter or muddy and sandy sediment of which these beds were originally composed. * Geology of Canada, 1863. t Report of the Geological Survey of Canada, 1866. THE LAUEENTIAN ROCKS. 29 " The quantity of graphite in the Lower Laurentian series is enormous. In a recent visit to the township of Buckingham, on the Ottawa Eiver, I examined a band of limestone believed to be a continuation of that described by Sir W. E. Logan as the Green Lake Limestone. It was estimated to amount, with some thin interstratified bands of gneiss, to a thickness of 600 feet or more, and was found to be filled with disseminated crystals of graphite and veins of the mineral to such an ex- tent as to constitute in some places one-fourth of the whole ; and making every allowance for the poorer portions, this band cannot contain in all a less vertical thickness of pure graphite than from twenty to thirty feet. In the adjoining township of Lochaber Sir W. E. Logan notices a band from twenty-five to thirty feet thick, reticulated with graphite veins to such an extent as to be mined with profit for the mineral. At another place in the same district a bed of graphite from ten to twelve feet thick, and yielding twenty per cent, of the pure material, is worked. When it is considered that graphite occurs in similar abundance at several other horizons, in beds of limestone which have been ascertained by Sir W. E. Logan to have an aggregate thickness of 3500 feet, it is scarcely an exaggeration to maintain that the quantity of carbon in the Laurentian is equal to that in similar areas of the Carboniferous system. It is also to be observed that an immense area in Canada appears to be occupied by these graphitic and Eozoon limestones, and that rich graphitic deposits exist in the continuation of this system in the State of New York, while in rocks believed to be of this age near St. John, New Brunswick, there is a very thick bed of graphitic limestone, and associated with it three regular beds of graphite, having an aggregate thickness of about five feet.* " It may fairly be assumed that in the present world and in those geological periods with whose organic remains we are more familiar than with those of the Laurentian, there is no other source of unoxidized carbon in rocks than that furnished by organic matter, and that this has obtained its carbon in all * Matthew, in Quart. Journ. Geol. Soc., vol. xxi., p. 423. Acadian Geology, p. 662. 30 THE DAWN OF LIFE. cases, in the first instance, from the deoxidation of carbonic acid by living plants. No other sonrce of carbon can, I believe, be imagined in the Laurentian period. We may, how- ever, suppose either that the graphitic matter of the Lauren- tian has been accumulated in beds like those of coal, or that it has consisted of diffused bituminous matter similar to that in more modern bituminous shales and bituminous and oil- bearing limestones. The beds of graphite near St. John, some of those in the gneiss at Ticonderoga in New York, and at Lochaber and Buckingham and elsewhere in Canada, are so pure and regular that one might fairly compare them with the graphitic coal of Ehode Island. These instances, however, are exceptional, and the greater part of the disseminated and vein graphite might rather be compared in its mode of occur- rence to the bituminous matter in bituminous shales and limestones. " We may compare the disseminated graphite to that which we find in those districts of Canada in which Silurian and Devonian bituminous shales and limestones have been meta- morphosed and converted into graphitic rocks not dissimilar to those in the less altered portions of the Laurentian.* In like manner it seems probable that the numerous reticulating veins of graphite may have been formed by the segregation of bituminous matter into fissures and planes of least resist- ance, in the manner in which such veins occur in modern bituminous limestones and shales. Such bituminous veins occur in the Lower Carboniferous limestone and shale of Dor- chester and Hillsborough, New Brunswick, with an arrange- ment very similar to that of the veins of graphite ; and in the Quebec rocks of Point Levi, veins attaining to a thickness of more than a foot, are filled with a coaly matter having a trans- verse columnar structure, and regarded by Logan and Hunt as an altered bitumen. These palaeozoic analogies would lead us to infer that the larger part of the Laurentian graphite falls under the second class of deposits above mentioned, and that, if of vegetable origin, the organic matter must have been *Granby, Melbourne, Owl's Head, etc., Geology of Canada, 1863, p. 599. THE LAURENTIAN BOOKS. 31 thoroughly disintegrated and bituminized before it was changed into graphite. This would also give a probability that the vegetation implied was aquatic, or at least that it was accumulated under water. " Dr. Hunt has, however, observed an indication of terres- trial vegetation, or at least of subaerial decay, in the great beds of Laurentian iron ore. These, if formed in the same manner as more modern deposits of this kind, would imply the reducing and solvent action of substances produced in the decay of plants. In this case such great ore beds as that of Hull, on the Ottawa, seventy feet thick, or that near ISTew- borough, 200 feet thick,* must represent a corresponding quantity of vegetable matter which has totally disappeared. It may be added that similar demands on vegetable matter as a deoxidizing agent are made by the beds and veins of metallic sulphides of the Laurentian, though some of the latter are no doubt of later date than the Laurentian rocks themselves. " It would be very desirable to confirm such conclusions as those above deduced by the evidence of actual microscopic structure. It is to be observed, however, that when, in more modern sediments, algae have been converted into bituminous matter, we cannot ordinarily obtain any structural eyidence of the origin of such bitumen, and in the graphitic slates and limestones derived from the metamorphosis of such rocks no organic structure remains. It is true that, in certain bitumin- ous shales and limestones of the Silurian system, shreds of organic tissue can sometimes be detected, and in some cases, as in the Lower Silurian limestone of the La Cloche mountains in Canada, the pores of brachiopodous shells and the cells of corals have been penetrated by black bituminous matter, forming what may be regarded as natural injections, some- times of much beauty. In correspondence with this, while in some Laurentian graphitic rocks, as, for instance, in the com- pact graphite of Clarendon, the carbon presents a curdled appearance due to segregation, and precisely similar to that of the bitumen in more modern bituminous rocks, I can detect in the graphitic limestones occasional fibrous structures which * Geology of Canada, 18G3. 32 THE DAWN OP LIFE. may be remains of plants, and in some specimens vermicular lines, which I believe to be tubes of Eozoon penetrated by matter once bituminous, but now in the state of graphite. "When palaeozoic land-plants have been converted into graphite, they sometimes perfectly retain their structure. Mineral charcoal, with structure, exists in the graphitic coal of Rhode Island. The fronds of ferns, with their minutest veins perfect, are preserved in the Devonian shales of St. John, in the state of graphite; and in the same formation there are trunks of Conifers (Dadoxylon ouangondianuni) in which the material of the cell-walls has been converted into graphite, while their cavities have been filled with calcareous spar and quartz, the finest structures being preserved quite as well as in comparatively unaltered specimens from the coal- formation.* No structures so perfect have as yet been de- tected in the Laurentian, though in the largest of the three graphitic beds at St. John there appear to be fibrous struc- tures which I believe may indicate the existence of land- plants. This graphite is composed of contorted and slicken- sided laminae, much like those of some bituminous shales and coarse coals ; . and in these there are occasional small pyritous masses which show hollow carbonaceous fibres, in some cases presenting obscure indications of lateral pores. I regard these indications, however, as uncertain; and it is not as yet fully ascertained that these beds at St. John are on the same geological horizon with the Lower Laurentian of Canada, though they certainly underlie the Primordial series of the Acadian group, and are separated from it by beds having the character of the Huronian. "There is thus no absolute impossibility that distinct organic tissues may be found in the Laurentian graphite, if formed from land-plants, more especially if any plants existed at that time having true woody or vascular tissues ; but it cannot with certainty be affirmed that such tissues have been found. It is possible, however, that in the Laurentian period the vegetation of the land may have consisted wholly * Acadian Geology, p. 535. In calcified specimens the structures remain in the graphite after decalcification by an acid. THE LAURENTIAN ROCKS. 33 of cellular plants, as, for example, mosses and lichens ; and if so, there would be comparatively little hope of the distinct preservation of their forms or tissues, or of our being able to distinguish the remains of land-plants from those of Algae. "We may sum up these facts and considerations in the following statements : First, that somewhat obscure traces of organic structure can be detected in the Laurentian graphite ; secondly, that the general arrangement and microscopic struc- ture of the substance corresponds with that of the carbon- aceous and bituminous matters in marine formations of more modern date ; thirdly, that if the Laurentian graphite has been derived from vegetable matter, it has only undergone a metamorphosis similar in kind to that which organic matter in metamorphosed sediment of later age has experienced; fourthly, that the association of the graphitic matter with organic limestone, beds of iron ore, and metallic sulphides, greatly strengthens the probability of its vegetable origin ; fifthly, that when we consider the immense thickness and extent of the Eozoonal and graphitic limestones and iron ore deposits of the Laurentian, if we admit the organic origin of the limestone and graphite, we must be prepared to believe that the life of that early period, though it may have ex- isted under low forms, was most copiously developed, and that it equalled, perhaps surpassed, in its results, in the way of geological accumulation, that of any subsequent period." (D.) WESTERN AND OTHER LAURENTIAN EOCKS, ETC. In the map of the Laurentian nucleus of America (fig. 4,) I have not inserted the Laurentian rocks believed to exist in the Eocky Mountains and other western ranges. Their dis- tribution is at present uncertain, as well as the date of their elevation. They may indicate an old line of Laurentian fracture or wrinkling, parallel to the west coast, and defining its direction. In the map there should be a patch of Lauren- tian in the north of Newfoundland, and it should be wider at the west end of lake Superior. Full details as to the Laurentian rocks of Canada and sec- D 34 THE DAWN OP LIFE. tional lists of their beds will be found in the Reports of the Geological Survey, and Dr. Hunt has discussed very fully their chemical characters and metamorphism in his Chemical and Geological Essays. The recent reports of Hitchcock on New Hampshire, and Hayden on the Western Territories', contain some new facts of interest. The former recognises in the White Mountain region a series of gneisses and other altered rocks of Lower Laurentian age, and, resting uncon- formably on these, others corresponding to the Upper Lau- rentian ; while above the latter are other pre-silurian formations corresponding to the Huronian and probably to the Montalban series of Hunt. These facts confirm Logan's results in Canada ; and Hitchcock finds many reasons to believe in the existence of life at the time of the deposition of these old rocks. Eayden's report describes granitic and gneissose rocks, pro- bably of Laurentian age, as appearing over great areas in Colorado, Arizona, Utah, and Nevada showing the existence of this old metamorphic floor over vast regions of Western America. The metamorphism of these rocks does not imply any change of their constituent elements, or interference with their bedded arrangement. It consists in the alteration of the sediments by merely molecular changes re-arranging their par- ticles so as to render them crystalline, or by chemical reactions producing new combinations of their elements. Experiment shows that the action of heat, pressure, and waters containing alkaline carbonates and silicates, would produce such changes. The amount and character of change would depend on the composition of the sediment, the heat applied, the substances in solution in the water, and the lapse of time. (See Hunt's Essays, p. 24.) CHAPTER III. THE HISTORY OF A DISCOVERY. IT is a trite remark that most discoveries are made, not by one person, but by the joint exertions of many, and that they have their preparations made often long be- fore they actually appear. In this case the stable foundations were laid, years before the discovery of Eozoon, by the careful surveys made by Sir William Logan and his assistants, and the chemical examina- tion of the rocks and minerals by Dr. Sterry Hunt. On the other hand, Dr. Carpenter and others in Eng- land were examining the structure of the shells of the humbler inhabitants of the modern ocean, and the manner in which the pores of their skeletons become infiltrated with mineral matter when deposited in the sea-bottom. These laborious and apparently dissimi- lar branches of scientific inquiry were destined to be united by a series of happy discoveries, made not for- tuitously but by painstaking and intelligent observers. The discovery of the most ancient fossil was thus not the chance picking up of a rare and curious specimen. It was not likely to be found in this way; and if so found, it would have remained unnoticed and of no scientific value, but for the accumulated stores of zoo- 36 THE DAWN OF LIFE. logical and palaoontological knowledge, and the sur- veys previously made, whereby the age and distribution of the Laurentian rocks and the chemical conditions of their deposition and metamorphism were ascer- tained. The first specimens of Eozoon ever procured, in so far as known, were collected at Burgess in Ontario by a veteran Canadian mineralogist, Dr. Wilson of Perth, and were sent to Sir William Logan as mineral specimens. Their chief interest at that time lay in the fact that certain laminse of a dark green mineral FIG. 7. Eozoon mineralized by Loganite and Dolomite. (Collected by Dr. Wilson, of Perth.) present in the specimens were found, on analysis by Dr. Hunt, to be composed of a new hydrous silicate, allied to serpentine, and which he named loganite: one of these specimens is represented in fig. 7. The form of this mineral was not suspected to be of organic origin. Some years after, in 1858, other specimens, differently mineralized with the minerals serpentine and pyrox- THE HISTORY OP A DISCOVERY. 37 ene, were found by Mr. J. McMullen, an explorer in the service of the Geological Survey, in the limestone of the Grand Calumet on the River Ottawa. These seein to have at once struck Sir W. E. Logan as re- sembling the Silurian fossils known as 8tromatoporu , and he showed them to Mr. Billings, the palaeontolo- gist of the survey, and to the writer, with this sugges- tion, confirming it with the sagacious consideration, that inasmuch as the Ottawa and Burgess specimens were mineralized by different substances, yet were alike in form, there was little probability that they were merely mineral or concretionary. Mr. Billings was naturally unwilling to risk his reputation in affirm- ing the organic nature of such specimens; and my own suggestion was that they should be sliced, and ex- amined microscopically, and that if fossils, as they presented merely concentric laminae and no cells, they would probably prove to be protozoa rather than corals. A few slices were accordingly made, but no definite structure could be detected. Nevertheless Sir William Logan took some of the specimens to the meeting of the American Association at Springfield,, in 1859, and exhibited them as possibly Laurentiau fossils ; but the announcement was evidently received with some incredulity. In 1862 they were exhibited by Sir William to some geological friends in London, but he remarks that " few seemed disposed to believe in their organic character, with the exception of my friend Professor Ramsay." In 1863 the General Re- port of the Geological Survey, summing up its work 38 THE DAWN OF LIFE. 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. 8 and 9.) 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 preservation 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 he might have 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 ex- ception to this, stating that though in the slices before examined no structure was apparent, still my impres- sion 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 speci- mens, and to 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 THE HISTORY OF A DISCOVERT. 39 FIG. 8. Weathered Specimen of Eozoonfrom the Calumet. (Collected by Mr. McMullen.) FIG. 9. Cross Section of the Specimen represented in Fig. 8. The dark parts are the laminae of calcareous matter converging to the outer surface. 40 THE DAWN OF LIFE. 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 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 Foraminifera, whose tubulated supplemental skeleton, as described and figured by Dr. Carpenter, and represented in speci- mens in my collection presented by him, was evidently of the same type with that preserved in the canals of these ancient fossils. Fig. 10 is an accurate represen- tation of the first seen group of canals penetrated by serpentine. On showing the structures discovered to Sir William Logan, he entered into the matter with enthusiasm, and had a great number of slices and afterwards of 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 examin- ing the typical specimens of Eozoon, but had slices prepared of every variety of Laurentian limestone, of altered limestones from the Primordial and Silurian, THE HISTORY OF A DISCOVERY. 41 and of serpentine marbles of all the varieties furnished by our collections. These were examined with ordi- nary and polarized light, and with every variety of illumination. Dr. Hunt, on his part, undertook the chemical investigation of the various associated minerals. An extensive series of notes and camera tracings were made of all the appearances observed ; FIG. 10. Group of Canals in the Supplemental Skeleton of Eozoon. Taken from the specimen in which they were first recognised. Magnified. and of some of the more important structures beauti- ful drawings were executed by the late Mr. H. S. Smith, the then palaeontological draughtsman of the Survey. The result of the whole investigation was a firm conviction that the structure was organic and foraminiferal, and that it could be distinguished from any merely mineral or crystalline forms occur- ring in these or other limestones. 42 THE DAWN OP LIFE. At this stage of the matter, and after exhibiting to Sir William all the characteristic appearances in com- parison with such concretionary, dendritic, and crystal- line 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 palseontolo- gist of the Survey, and as our highest authority on the fossils of the older rocks. I was engaged in other researches, and 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 characteristic caution and modesty, declined. His hands, he said, were full of other work, and he had not specially studied the microscopic ap- pearances of Foraminifera or of mineral substances. It was finally arranged that I should prepare a de- scription of the fossil, which Sir William would take to London, along with Dr. Hunt's notes, the more im- portant specimens, and lists of 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 eminent authorities would confirm our conclusions, and bring forward new . facts which 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 the structure of the primary THE HISTORY OF A DISCOVEEY. 43 cell-wall, which I had not observed previously through a curious accident as to specimens.* Mr. Lowe had been sent back to the Ottawa to explore, and just be- fore Sir "William's departure had sent in some speci- mens from a new locality at Petite Nation, similar in general appearance to those from Grenville, which Sir FIG. 11. Portion of Eozoon magnified 100 diameters, showing the original Cell-wall with Tubulation, and the Supplemental Skeleton with Canals. (After Carpenter.} (a.) Original tubulated wall or " Nummuline layer," more magnified in fig. 2. (b, c.) " Intermediate skeleton," with canals. William took with him unsliced to England. These showed in a perfect manner the tubuli of the primary cell- wall, which I had in vain tried to resolve in the * In papers by Dr. Carpenter, subsequently referred to. Prof. Jones published an able exposition of the facts in the Popular Science Monthly. 44 THE DAWN OF LIFE. Grenville specimens, and which I did not see until after it had been detected by Dr. Carpenter in Lon- don. Dr. Carpenter thus contributed in a very im- portant manner to the perfecting of the investigations begun in Canada, and on him has fallen the greater part of their illustration and defence,* in so far as Great Britain is concerned. Fig. 11, taken from one of Dr. Carpenter's papers, shows the tubulated primitive wall as described by him. The immediate result was a composite paper in the Proceedings of the Geological Society, by Sir W. E. Logan, Dr. Carpenter, Dr. Hunt, and myself, in which the geology, palaeontology, and mineralogy of Eozoon Canadense and its containing rocks were first given to the world.f 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 con- tain its first traces, as these are before the middle period of the earth's life history, some hesitation 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 * In Quarterly Journal of Geological Society, vol. xxii. ; Proc. Eoyal Society, vol. xv. ; Intellectual Observer, 1865. Annals and Magazine of Natural History, 1874 ; and other papers and notices. f Journal Geological Society, February, 1865. THE HISTORY OP A DISCOVERY. 45 types of animals, and of the conditions of mineraliza- tion of organic remains, possessed by few even of pro- fessional geologists. Thus Eozoon has met with some negative scepticism and a little positive opposition, though the latter has been small in amount, when we consider the novel and startling character of the facts adduced. "The united thickness," says Sir William Logan, " of these three great series, the Lower and Upper Laurentian and Huronian, may possibly far surpass that of all succeeding rocks, from the base of the Paleo- zoic to the present time. We are thus carried back to a period so far remote that the appearance of the so-called Primordial fauna may be considered a com- paratively modern event." So great a revolution of thought, and this based on one fossil, of a character little recognisable by geologists generally, might well tax the faith of a class of men usually regarded as somewhat faithless and sceptical. Yet this new exten- sion of life has been generally received, and has found its way into text-books and popular treatises. Its opponents have been under the necessity of inventing the most strange and incredible pseudomorphoses of mineral substances to account for the facts; and evidently hold out rather in the spirit of adhesion to a lost cause than with any hope of ultimate success. As might have been expected, after the publication of the original paper, other facts developed themselves. Mr. Vennor found other and scarcely altered speci- mens in the Upper Laurentian or Huronian of Tudor. 46 THE DAWN OP LIFE. Gumbel recognised the organism in Laurentian Rocks in Bavaria and elsewhere in Europe, and discovered a new species in the Huronian of Bavaria."* Eozoon was recognised in Laurentian limestones in Massa- chusetts f and New York, and there has been a rapid growth of new facts increasing our knowledge of Fora- minifera of similar types in the succeeding Palaeozoic rocks. Special interest attaches to the discovery by Mr. Vennor of specimens of Eozoon contained in a dark micaceous limestone at Tudor, in Ontario, and really as little metamorphosed as many Silurian fossils. Though in this state they show their minute structures less perfectly than in the serpentine specimens, the fact is most important with reference to the vindica- tion of the animal nature of Eozoon. Another fact whose significance is not to be over-estimated, is the recognition both by Dr. Carpenter and myself of speci- mens in which the canals are occupied by calcite like that of the organism itself. Quite recently I have, as mentioned in the last chapter, been enabled to re-ex- amine the locality at Petite Nation originally disco- vered by Mr. Lowe, and am prepared to show that all the facts with reference to the mode of occurrence of * Ueber das Vorkommen von Eozoon, 1866. f By Mr. Bicknell at ISTewbury, and Mr. Burbank at Chelms- ford. The latter gentleman has since maintained that the limestones at the latter place are not true beds; but his own descriptions and figures, lead to the belief that this is an error of observation on his part. The Eozoon in the Chelms- ford specimens and in those of Warren, New York, is in small and rare fragments in serpentinous limestone. THE HISTORY OP A DISCOVERY. 47 the forms in the beds, and their association with layers of fragmental Eozoon, are strictly in accordance with the theory that these old Laurentian limestones are truly marine deposits, holding the remains of the sea animals of their time. Eozoon is not, however, the only witness to the great fact of Laurentian life, of which it is the most conspicuous exponent. In many of the Laurentian limestones, mixed with innumerable fragments of Eozoon, there are other fragments with traces of organic structure of a different character. There are also casts in silicious matter which seem to indicate smaller species of Foraminifera. There are besides to be summoned in evidence the enormous accumula- tions of carbon already referred to as existing in the Laurentian rocks, and the worm-burrows, of which very perfect traces exist in rocks probably of Upper Eozoic age. Other discoveries also are foreshadowed here. The microscope may yet detect the true nature and affi- nities of some of the fragments associated with Eozoon. Less altered portions of the Laurentian rocks may be found, where even the vegetable matter may retain its organic forms, and where fossils may be recognised by their external outlines as well as by their internal structure. The Upper Laurentian and the Huronian have yet to yield up their stores of life. Thus the time may come when the rocks now called Primordial shall not be held to be so in any strict sense, and when swarming dynasties of Protozoa and other low forms 48 THE DAWN OP LIFE. of life may be known as inhabitants of oceans vastly ancient as compared with even the old Primordial seas. Who knows whether even the land of the Lau- rentian time may not have" been clothed with plants, perhaps as much more strange and weird than those of the Devonian and Carboniferous, as those of the lat- ter are when compared with modern forests ? NOTES TO CHAPTER III. (A.) Sm WILLIAM E. LOGAN ON THE DISCOVERT CHARACTERS OF EOZOON. [Journal of Geological Society, February, 1865.] " In the examination of these ancient rocks, the question has often naturally occurred to me, whether during these remote periods, life had yet appeared on the earth. The apparent absence of fossils from the highly crystalline lime- stones did not seem to offer a proof in the negative, any more than their undiscovered presence in newer crystalline lime- stones where we have little doubt they have been obliterated by metamorphic action ; while the carbon which, in the form of graphite, constitutes beds, or is disseminated through the calcareous or siliceous strata of the Laurentian series, seems to be an evidence of the existence of vegetation, since no one disputes the organic character of this mineral in more recent rocks. My colleague, Dr. T. Sterry Hunt, ha-s argued for the existence of organic matters at the earth's surface during the Laurentian period from the presence of great beds of iron ore, and from the occurrence of metallic sulphurets ; * and finally, the evidence was strengthened by the discovery of supposed organic forms. These were first brought to me, in October, 1858, by Mr. J. McMullen, then attached as an explorer to the * Quarterly Journal of the Geological Society, xv. , 493. THE HISTOEY OP A DISCOVEEY. 49 Geological Survey of the province, from one of the limestones of the Laurentian series occurring at the Grand Calumet, on the river Ottawa. " Any organic remains which may have been entombed in these limestones would, if they retained their calcareous cha- racter, be almost certainly obliterated by crystallization ; and it would only be by the replacement of the original carbonate of lime by a different mineral substance, or by an infiltration of such a substance into all the pores and spaces in and about the fossil, that its form would be preserved. The specimens from the Grand Calumet present parallel or apparently concen- tric layers resembling those of Stromatopora, except that they anastomose at various points. What were first considered the layers are composed of crystallized pyroxene, while the then supposed interstices consist of carbonate of lime. These specimens, one of which is figured in Geology of Canada, p. 49, called to memory others which had some years previously been obtained from Dr. James Wilson, of Perth, and were then regarded merely as minerals. They came, I believe, from masses in Burgess, but whether in place is not quite certain; and they exhibit similar forms to those of the Grand Calumet, composed of layers of a dark green magnesian silicate (loganite) ; while what were taken for the interstices are filled with crystalline dolomite. If the specimens from both these places were % to be regarded as the result of unaided mineral arrangement, it appeared to me strange that identical forms should be derived from minerals of such different composition. I was therefore disposed to look upon them as fossils, and as such they were exhibited by me at the meeting of the American Association for the Advancement of Science, at Springfield, in August, 1859. See Canadian Naturalist, 1859, iv., 300. In 1862 they were shown to some of my geological friends in Great Britain; but no microscopic structure having been observed belonging to them, few seemed disposed to believe in their organic character, with tho exception of my friend Professor Ramsay. " One of the specimens had been sliced and submitted to microscopic observation, but unfortunately it was one of those 50 THE DAWN OF LIFE. composed of loganite and dolomite. In these, the minute structure is rarely seen. The true character of the specimens thus remained in suspense until last winter, when I accident- ally observed indications of similar forms in blocks of Lauren- tian limestone which had been brought to our museum by Mr. James Lowe, one of our explorers, to be sawn up for marble. In this case the forms were composed of serpentine and calc- spar ; and slices of them having been prepared for the micro- scope, the minute structure was observed in the first one submitted to inspection. At the request of Mr. Billings, the palaeontologist of our Survey, the specimens were confided for examination and description to Dr. J. W. Dawson, of Montreal, our most practised observer with the microscope; and the conclusions at which he has arrived are appended to this com- munication. He finds that the serpentine, which was supposed to replace the organic form, really fills the interspaces of the calcareous fossil. This exhibits in some parts a well-preserved organic structure, which Dr. Dawson describes as that of a Foraminif er, growing in large sessile patches after the manner of Polytrema and Carpenteria, but of much larger dimensions, and presenting minute points which reveal a structure re- sembling that of other Foraminiferal forms, as, for example Calcarina and Nummulina. " Dr. Dawson's description is accompanied by some remarks by Dr. Sterry Hunt on the mineralogical relations of the fossil. He observes that while the calcareous septa which form the skeleton of the Foraminifer in general remain unchanged, the sarcode has been replaced by certain silicates which have not only filled up the chambers, cells, and septal orifices, but have been injected into the minute tubuli, which are thus perfectly preserved, as may be seen by removing the calcareous matter by an acid. The replacing silicates are white pyroxene, serpen- tine, loganite, and pyrallolite or rensselaerite. The pyroxene and serpentine are often found in contact, filling contiguous chambers in the fossil, and were evidently formed in consecu- tive stages of a continuous process. In the Burgess specimens, while the sarcode is replaced by loganite, the calcareous skele- ton, as has already been stated, has been replaced by dolomite, THE HISTOEY OF A DISCOVERY. 51 and the finer parts of the structure have been almost wholly obliterated. But in the other specimens, where the skeleton still preserves its calcareous character, the resemblance between the mode of preservation of the ancient Laurentian Foramini- fera, and that of the allied forms in Tertiary and recent de- posits (which, as Ehrenberg, Bailey, and Pourtales have shown, are injected with glauconite), is obvious. " The Grenville specimens belong to the highest of the three already mentioned zones of Laurentian limestone, and it has not yet been ascertained whether the fossil extends to the two conformable lower ones, or to the calcareous zones of the over- lying unconformable Upper Laurentian series. It has not yet either been determined what relation the strata from which the Burgess and Grand Calumet specimens have been obtained bear to the Grenville limestone or to one another. The zone of Grenville limestone is in some places about 1500 feet thick, and it appears to be divided for considerable distances into two or three parts by very thick bands of gneiss. One of these occupies a position towards the lower part of the lime- stone, and may have a volume of between 100 and 200 feet. It is at the base of the limestone that the fossil occurs. This part of the zone is largely composed of great and small irregu- lar masses of white crystalline pyroxene, some of them twenty yards in length by four or five wide. They appear to be con- fusedly placed one above another, with many ragged interstices, and smoothly- worn, rounded, large and small pits and sub- cylindrical cavities, some of them pretty deep. The pyroxene, though it appears compact, presents a multitude of small spaces consisting of carbonate of lime, and many of these show minute structures similar to that of the fossil. These masses of pyroxene may characterize a thickness of about 200 feet, and the interspaces among them are filled with a mixture of serpentine and carbonate of lime. In general a sheet of pure dark green serpentine invests each mass of pyroxene ; the thickness of the serpentine, varying from the sixteenth of an inch to several inches, rarely exceeding half a foot. This is followed in different spots by parallel, waving, irregularly alternating plates of carbonate of lime and serpentine, which 52 THE DAWN OF LIFE. become gradually finer as they recede from the pyroxene, and occasionally occupy a total thickness of five or six inches. These portions constitute the unbroken fossil, which may sometimes spread over an area of about a square foot, or per- haps more. Other parts, immediately on the outside of the sheet of serpentine, are occupied with about the same thick- ness of what appear to be the ruins of the fossil, broken up into a more or less granular mixture of calc-spar and serpen- tine, the former still showing minute structure ; and on the outside of the whole a similar mixture appears to have been swept by currents and eddies into rudely parallel and curving layers ; the mixture becoming gradually more calcareous as it recedes from the pyroxene. Sometimes beds of limestone of several feet in thickness, with the green serpentine more or less aggregated into layers, and studded with isolated lumps of pyroxene, are irregularly interstratified in the mass of rock ; and less frequently there are met with lenticular patches of sandstone or granular quartzite, of a foot in thickness and several yards in diameter, holding in abundance small dis- seminated leaves of graphite. " The general character of the rock connected with the fossil produces the impression that it is a great Foraminiferal reef, in which the pyroxenic masses represent a more ancient por- tion, which having died, and having become much broken up and worn into cavities and deep recesses, afforded a seat for a new growth of Foraminifera, represented by the calcareo-ser- pentinous part. This in its turn became broken up, leaving in some places uninjured portions of the general form. The main difference between this Foraminiferal reef and more re- cent coral-reefs seems to be that, while in the latter are usually associated many shells and other organic remains, in the more ancient one the only remains yet found are those of the animal which built the reef." (B.) NOTE BY SIR WILLIAM E. LOGAN, ON ADDITIONAL SPECIMENS OF EOZOON. [Journal of Geological Society, August, 1867.] " Since the subject of Laurentian fossils was placed before this Society in the papers of Dr. Dawson, Dr. Carpenter, Dr. THE HISTOEY OF A DISCOVEEY. 53 T. Sterry Hunt, and myself, in 1865, additional specimens of Eozoon have been obtained during the explorations of the Geological Survey of Canada. These, as in the case of the specimens first discovered, have been submitted to the ex- amination of Dr. Dawson; and it will be observed, from his remarks contained in the paper which is to follow, that one of them has afforded further, and what appears to him conclusive, evidence of their organic character. The speci- mens and remarks have been submitted to Dr. Carpenter, who coincides with Dr. Dawson; and the object of what I have to say in connection with these new specimens is merely to point out the localities in which they have been procured. " The most important of these specimens was met with last summer by Mr. G. H. Vennor, one of the assistants on the Canadian Geological Survey, in the township of Tudor and county of Hastings, Ontario, about forty-five miles inland from the north shore of Lake Ontario, west of Kingston. It occurred on the surface of a layer, three inches thick, of dark grey micaceous limestone or calc-schist, near the middle of a great zone of similar rock, which is interstratified with beds of yellowish-brown sandstone, gray close grained silicious lime- stone, white coarsely granular limestone, and bands of dark bluish compact limestone and black pyritif erous slates, to the whole of which Mr. Yennor gives a thickness of 1000 feet. Beneath this zone are gray and pink dolomites, bluish and grayish mica slates, with conglomerates, diorites, and beds of magnetite, a red orthoclase gneiss lying at the base. The whole series, according to Mr. Vennor's section, which is ap- pended, has a thickness of more than 12,000 feet ; but the possible occurrence of more numerous folds than have hitherto been detected, may hereafter render necessary a considerable reduction. " These measures appear to be arranged in the form of a trough, to the eastward of which, and probably beneath them, there are rocks resembling those of Grenville, from which the former differ considerably in lithological character ; it is there- fore supposed that the Hastings series may be somewhat 54 THE DAWN OF LIFE. higher in horizon than that of Grenville. From the village of Madoc, the zone of gray micaceous limestone, which has been particularly alluded to, runs to the eastward on one side of the trough, in a nearly vertical position into Elzivir, and on the other side to the northward, through the township of Madoc into- that of Tudor, partially and unconformably overlaid in several places by horizontal beds of Lower Silurian limestone, but gradually spreading, from a diminution of the dip, from a breadth of half a mile to one of four miles. Where it thus spreads out in Tudor it becomes suddenly interrupted for a considerable part of its breadth by an isolated mass of anortho- site rock, rising about 150 feet above the general plain, and supposed to belong to the unconformable Upper Laurentian." [Subsequent observations, however, render it probable that some of the above beds may be Huronian.] "The Tudor limestone is comparatively unaltered : and, in the specimen obtained from it, the general form or skeleton of the fossil (consisting of white carbonate of lime) is imbedded in the limestone, without the presence of serpentine or other silicate, the colour of the skeleton contrasting strongly with that of the rock. It does not sink deep into the rock, the form having probably been loose and much abraded on what is now the under part, before being entombed. On what was the surface of the bed, the form presents a well-defined out- line on one side ; in this and in the arrangement of the septal layers it has a marked resemblance to the specimen first brought from the Calumet, eighty miles to the north-east, and figured in the Geology of Canada, p. 49 ; while all the forms from the Calumet, like that from Tudor, are isolated, imbedded specimens, unconnected apparently with any continuous reef, such as exists at Grenville and the Petite Nation. It will be seen, from Dr. Dawson's paper, that the minute structure is present in the Tudor specimen, though somewhat obscure; but in respect to this, strong subsidiary evidence is derived from fragments of Eozoon detected by Dr. Dawson in a speci- men collected by myself from the same zone of limestone near the village of Madoc, in which the canal- system, much more distinctly displayed, is filled with carbonate of lime, as quoted THE HISTOEY OF A DISCOVERY. 55 from Dr. Dawson by Dr. Carpenter in the Journal of this Society for August, 1866. "In Dr. Dawson's paper mention is made of specimens from Wentworth, and others from Long Lake. In both of these localities the rock yielding them belongs to the Gren- ville band, which is the uppermost of the three great bands of limestone hitherto described as interstratified in the Lower Laurentian series. That at Long Lake, situated about twenty- five miles north of Cote St. Pierre in the Petite Nation seigniory, where the best of the previous specimens were obtained, is in the direct run of the limestone there : and like it the Long Lake rock is of a serpentinous character. The locality in Wentworth occurs on Lake Louisa, about sixteen miles north of east from that of the first Grenville specimens, from which Cote St. Pierre is about the same distance north of west, the lines measuring these distances running across several important undulations in the Grenville band in both directions. The Wentworth specimens are imbedded in a portion of the Grenville band, which appears to have escaped any great alteration, and is free from serpentine, though a mixture of serpentine with white crystalline limestone occurs in the band within a mile of the spot. From this grey lime- stone, which has somewhat the aspect of a conglomerate, specimens have been obtained resembling some of the figures given by Giimbel in his Illustrations of the forms met with by him in the Laurentian rocks of Bavaria. " In decalcifying by means of a dilute acid some of the specimens from Cote St. Pierre, placed in his hands in 1864-65, Dr. Carpenter found that the action of the acid was arrested at certain portions of the skeleton, presenting a yellowish- brown surface ; and he showed me, two or three weeks ago, that in a specimen recently given him, from the same locality, considerable portions of the general form remained undissolved by such an acid. On partially reducing some of these portions to a powder, however, we immediately observed effervescence by the dilute acid; and strong acid produced it without bruis- ing. There is little doubt that these portions of the skeleton are partially replaced by dolomite, as more recent fossils are 56 THE DAWN OF LIFE. often known to be, of which there is a noted instance in the Trenton limestone of Ottawa. But the circumstance is alluded to for the purpose of comparing these dolomitized portions of the skeleton with the specimens from Burgess, in which the replacement of the septal layers by dolomite appears to be the general condition. In such of these specimens as have been examined the minute structure seems to be wholly, or almost wholly, destroyed ; but it is probable that upon a further in- vestigation of the locality some spots will be found to yield specimens in which the calcareous skeleton still exists unre- placed by dolomite ; and I may safely venture to predict that in such specimens the minute structure, in respect both to canals and tubuli, will be found as well preserved as in any of the specimens from Cote St. Pierre. " It was the general form on weathered surfaces, and its strong resemblance to Stromatopora, which first attracted my attention to Eozoon ; and the persistence of it in two distinct minerals, pyroxene and loganite, emboldened me, in 1857, to place before the Meeting of the American Association for the Advancement of Science specimens of it as probably a Lauren - tian fossil. After that, the form was found preserved in a third mineral, serpentine ; and in one of the previous specimens it was then observed to pass continuously through two of the min- erals, pyroxene and serpentine. Now we have it imbedded in limestone, just as most fossils are. In every case, with the ex- ception of the Burgess specimens, the general form is composed of carbonate of lime; and we have good grounds for supposing it was originally so in the Burgess specimens also. If, there- fore, with such evidence, and without the minute structure, I was, upon a calculation of chances, disposed, in 1857, to look upon the form as organic, much more must I so regard it when the chances have been so much augmented by the subsequent accumulation of evidence of the same kind, and the addition of the minute structure, as described by Dr. Dawson, whose observations have been confirmed and added to by the highest British authority upon the class of animals to which the form has been referred, leaving in my mind no room whatever for doubt of its organic character. Objections to it as an or- THE HISTORY OF A DISCOVERS". 57 ganism have been made by Professors King and Rowney : but these appear to ine to be based upon the supposition that be- cause some parts simulating organic structure are undoubtedly mere mineral arrangement, therefore all parts are mineral. Dr. Dawson has not proceeded upon the opposite supposition, that because some parts are, in his opinion, undoubtedly organic, therefore all parts simulating organic structure are organic ; but he has carefully distinguished between the mineral and organic arrangements. I am aware, from having supplied him with a vast number of specimens prepared for the microscope by the lapidary of the Canadian Survey, from a series of rocks of Silurian and Huronian, as well as Laurentian age, and from having followed the course of his investigation as it proceeded, that nearly all the points of objection of Messrs. King and Eowney passed in review before him prior to his coming to the conclusions which he has published." Ascending Section of the Eozoic Rocks in tlie County of Hastings, Ontario. By Mr. H. G. VENNOR. 1. Eeddish and flesh-coloured granitic gneiss, the thick- Feet, ness of which is unknown; estimated at not less than 2,000 2. Grayish and flesh-coloured gneiss, sometimes horn- blendic, passing towards the summit into a dark mica- schist, and including portions of greenish- white diorite ; mean of several pretty closely agreeing measurements, 10,400 3. Crystalline limestone, sometimes magnesian, in- cluding lenticular patches of quartz, and broken and contorted layers of quartzo-felspathic rock, rarely above a few inches in thickness. This limestone, which in- cludes in Elzivir a one-foot bed of graphite, is some- times very thin, but in other places attains a thickness of 750 feet ; estimated as averaging 400 4. Hornblendic and dioritic rocks, massive or schis- tose, occasionally associated near the base with dark micaceous schists, and also with chloritic and epidotic rocks, including beds of magnetite; average thickness 4,200 5. Crystalline and somewhat granular magnesian 58 THE DAWN OF LIFE. limestone, occasionally interstratified with diorites, and near the base with silicious slates and small beds of impure steatite 330 This limestone, which is often silicious and ferrugin- ous, is metalliferous, holding disseminated copper pyrites, blende, mispickel, and iron- pyrites, the latter also sometimes in beds of two or three feet. Gold occurs in the limestone- at the village of Madoc, associated with an argentiferous gray copper ore, and in irregular veins with bitter-spar, quartz, and a carbonaceous matter, at the Richardson mine in Madoc. 6. Gray silicious or fmed-grained 'mica-slates, with an interstratified mass of about sixty feet of yellowish- white dolomite- divided into beds by thin layers of the mica-slate, which, as well as the dolomite, often becomes conglomerate, including rounded masses of gneiss and quartzite from one to twelve inches in diameter 400 7. Bluish and grayish micaceous slate, interstratified with layers of gneiss, and occasionally holding crystals of magnetite. The whole division weathers to a rusty- brown 500 8. Gneissoid micaceous quartzites, banded gray and white, with a few instratified beds of silicious lime- stone, and, like the last division, weathering rusty brown 1,900 9. Gray micaceous limestone, sometimes plumbagin- ous, becoming on its upper portion a calc-schist, but more massive towards the base, where it is interstratified with occasional layers of diorite, and layers of a rusty- weathering gneiss like 8 1 ,1 00 This division in Tudor is traversed by numerous N.W. and S.E. veins, holding galena in a gangue of calcite and barytine. The Eozoon from Tudor here described was obtained from about the middle of this calcareous division, which appears to form, the summit of the Hastings series. Total thickness .. .. 21,130 PLATE IV. Magnified and Restored Section of a portion of Eozoon Canadense. The portions in brown show the animal matter of the Chambers, Tubuli, Canals, and Pseudopodia; the portions uncoloured, the calcareous skeleton. CHAPTER IV. WHAT IS EOZOON f THE- shortest answer to this question is,, that this ancient fossil is 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 Amoeba* (fig. 12), it will form a convenient starting point. Viewed under a low power, it appears 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 pseudo- pods 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 organized jelly or protoplasm. When minutely examined, however, it will not be found so simple as it at first sight appears. Its outer layer * The alternating animal, alluding to its change of form. 60 THE DAWN OF LIFE. is clear or 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, FIG. 12. Amoeba. FIG. 13. Actinophrys. From original sketches. which is a little cell capable, at certain times, of pro- ducing by its division new individuals. Food when taken in through the wall of the body forms little pellets, which become surrounded by a 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 WHAT IS EOZOON ? 61 body is capable of protrusion in any direction into long processes, which are very mobile, and used for locomo- tion and prehension. Further, this creature, though destitute of most of the parts which we are accustomed to regard as proper to animals, seems to exercise voli- tion, and to show the same appetites and passions with animals of higher type. I have watched one of these animalcules 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 Pro- tozoa, but somewhat differently organized. One of these, Actinophrys (fig. 13), has the body globular and unchanging in form, the outer wall of greater thick- ness ; the pulsating vesicle like a blister on the surface, and the pseudopods long and thread-like. Its habits are similar to those of the Amoeba, and I introduce it to show the variations of form and structure possible even among these simple creatures. The Amoeba and Actinophrys are fresh water animals, and are destitute of any shell or covering. But in the sea there exist 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 THE DAWN OF LIFE. FIG. 14. Entosolenia. A one-celled Foraminifer. Magnified as a transparent object. FIG. 15. Biloculina. A many-chambered Foraminifer. Magnified as a transparent tfbject. FIG. 16. Polystomella. A spiral Foraminifer. Magnified as an opaque object. WHAT IS EOZOON? 63 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 other- wise in most beautiful and symmetrical forms. Some of these creatures, usually named Foraminifera, are FIG. 17. Polymorphina. A many- chambered Foramim'fer. Magnified as an opaque object. Figs. 14 to 17 are from original sketches of Post-pliocene specimens. 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. (Figs. 14 to 17.) The original skeleton or primary cell-wall of most of these creatures is seen under the microscope to be per- forated 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 64 THE DAWN OP LIFE. give strength, this is done by adding new portions of carbonate of lime to the outside, and to these Dr. Car- penter has given the appropriate name of " supplemen- tal skeleton ; " and this, when covered by new growths, becomes what he has termed an " intermediate skele- ton." The supplemental skeleton is also traversed by tubes, but these are often of larger size than the pores of the cell- wall, and of greater length, and branched in a complicated manner. (Fig. 20.) Thus there are micro- scopic characters by which these curious shells can 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 accumu- lation takes place we learn from what is now going 011 in the ocean, more especially from the result of the recent deep-sea dredging expeditions. The Foramini- fera are vastly numerous, both near the surface and at the bottom of the sea, and multiply rapidly ; and as successive 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 hard- ened 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 the nummulitic limestone of Europe and the orbitoidal WHAT IS EOZOON ? 65 limestone of America. The chalk, which alone attains a maximum thickness of 1000 feet, and, according to Lyell, can be traced across Europe for 1100 geographical miles, may be said to be entirely composed of shells of Foraminifera imbedded in a paste of still more minute calcareous bodies, the Coccoliths, which are probably products of marine vegetable life, if not of some animal organism still simpler than the Foraminifera. Lastly, we find that in the earlier geological ages there existed much larger Foraminifera than any found in our present seas ; and that these, always sessile on the bottom, grew by the addition of successive chambers, in the same manner with the smaller species. To some of these we shall return in the sequel. In the mean- time we shall see what claims Eozoon has to be in- cluded among them. Let us, then, examine the structure of Eozoon, taking a typical specimen, as we find it in the limestone of Grenville or Petite Nation. In such specimens the skeleton of the animal is represented by a white crys- talline marble, the cavities of the cells by green serpen- tine, the mode of whose introduction we shall have to consider in the sequel. The lowest layer of serpentine 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, in appearance at least, the shapeless coat of living slime found in some portions of the bed of the deep sea, which has received from I 66 THE DAWN OF LIFE. Huxley the name BathybiuSj and which is believed to be a protozoon of indefinite extension, though it may possibly be merely the pulpy sarcode of sponges and similar things penetrating the ooze at their bases. On this primary layer grew a delicate calcareous shell, per- forated by innumerable minute tubuli, and by some larger pores or septal orifices, while supported at inter- vals by perpendicular plates or pillars. Upon this again was built up, in order to strengthen it, a thickening or supplemental skeleton, more dense, and destitute of fine tubuli, but traversed by branching canals, through which the soft gelatinous matter could pass for the nourishment of the skeleton itself, and the extension of pseudopods beyond it. (Fig. 10.) So was formed the first layer of Eozoon, which seems in some cases to have spread by lateral extension over several inches of sea bottom. On this the process of growth of succes- sive 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. (Photograph, Plate III., and nature print, Plate V.) As the process went on, however, the vitality of the organism became exhausted, probably by the deficient nourishment of the central and lower layers making greater and greater demands on those above, and so the succeeding layers became thinner, and less supplemental skeleton was developed. Finally, toward the top, the regular arrangement in layers was abandoned, and the cells became a mass of rounded chambers, irregularly piled up in what Dr. Carpenter has termed an "acervuline " WHAT IS EOZOON f 67 manner, and with very thin walls unprotected by sup- plemental 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 in connection with irregular Eozoon in one of the Laurentian limestones at Long Lake and elsewhere. FIG. 18. Minute Foraminiferal forms from the Laurentian of Long Lake. Highly magnified, (a.) Single cell, showing tubulated wall, (b, c.) Portions of same more highly magnified. ( 123 ; on Laurentian Life, 27 ; his Re- ply to Objections, 199. Huronian Rocks, 9. Intermediate Skeleton, 64. Iron Ores of Laurentian, 19. Jones, Prof. T. Rupert, on Eozoon, 42. King, Prof., his Objections, 184. Labrador Felspar, 13. Laurentian Rooks, 7; Fossils of, 130; Graphite of, 18,- 27; Iron Ores of, 19; Limestones of, 17. Limestones, Laurentian, 17 ; Silurian, 98. Localities of Eozoon, 166. Loftusia, 164. Logan, Sir Wm., referred to, 36 ; on Laurentian, 24 ; on Nature of Eozoon, 37 ; Geological Re- lations of Eozoon, 48; on Ad- ditional Specimens of Eozoon, 52. Loganite in Eozoonj 36, 102. Lowe, Mr., referred to, 38. Long Lake, Specimens from, 91. Lyell, Sir C., on Eozoon, 234. Madoc, Specimens from, 132. Maps of Laurentian, 7, 16. MacMullen, Mr., referred to, 37. Metamorphism of Rocks, 13,34. Mineralization of Eozoon, 101 ; of Fossils, 93 ; Hunt on, 115. Nicholson on Stromatopora, 165. Nummulites, 73.. Nummuline Wall, 43, 65, 106, 176, 181. Objections- answered, 169, 188. Parkeria, 164. Petite Nation, 20, 43. Pole Hill, Specimens from, 121. Proper Wall; 43, 65, 106, 176, 181. Preservation of Eozoon, 93. Protozoa, their Nature, 59, 207. Pseudomorphism, 200. Pyroxene filling Eozoon, 108. Red Clay of Pacific, 222. Red Chalk, 222. Reply to Objections, 167, 188. Receptaculites, 162. Robb, Mr., referred to, 120. Rowney, Prof., Objections of, 184. Serpentine mineralizing Eozoon, 102. INDEX. 239 Silicates mineralizing Fossils, 100, 103, 121, 220. Silurian Fossils infiltrated with Silicates, 121. Steinhag, Eozoon of, 146. Stromatopora, 37, 156. Stromatoporidffl, 165. Supplemental Skeleton, 64.. Table of. Formations, 6<. Trinity Cape, 10. Tubuli Explained, 66, 106. Varieties of Eozoon, 135, 236. Vennor, Mr., referred to, 46, 57. Wentworth Specimens, 91. Weston, Mr., referred to, 20, 40, 162. Wilson, Dr. , referred to, 36. Worm-burrows in the Lauren tian, 133, 139.- Butler & Tanner. The Selwood Priuting Works. Frome. and Loudc 14 DAY USE RETURN TO DESK FROM WHICH BORROWED EARTH SCIENCES LIBRARY This book is due on the last date stamped below, or on the date to which renewed. Renewed books are subiect to immediate recall. DEC 1 7 1962 RET'D TO EARTH < PTTTNr i ir ri T TT3 DblJliNv_/llQ IjljD* JAN 2 2 iQfil i t* 1 fc/ JvJUO t/oO^ "MM^Hf??--: LD 21-50m-12,'61 (04796810)476 General Library University of California Berkeley -184