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If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Life's Dawn on Earth - Being the history of the oldest known fossil remains, and - their relations to geological time and to the development - of the animal kingdom - -Author: John William, Sir Dawson - -Release Date: December 25, 2015 [EBook #50767] - -Language: English - -Character set encoding: UTF-8 - -*** START OF THIS PROJECT GUTENBERG EBOOK LIFE'S DAWN ON EARTH *** - - - - -Produced by MWS, Tom Cosmas, Bryan Ness and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - - - - -Transcriber Notes - - -Text emphasis denoted as _Italics_. - - - - -[Illustration: - Plate I. - - From a Photo. by Henderson Vincent Brooke, Day & Son. Lith. - - - CAPE TRINITY ON THE SAGUENAY. - A CLIFF OF LAURENTIAN GNEISS. - - _Frontispiece_] - - - - - LIFE'S DAWN ON EARTH: - - BEING THE - - History of the Oldest Known Fossil Remains, - - AND - - THEIR RELATIONS TO GEOLOGICAL TIME - AND TO THE DEVELOPMENT OF - THE ANIMAL KINGDOM. - - - BY - - J. W. DAWSON, LL.D., F.R.S., F.G.S., Etc., - - PRINCIPAL AND VICE-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. - MDCCCLXXV. - - - - - Butler & Tanner, - The Selwood Printing Works, - Frome, and London. - - -To the Memory of - -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. - - - - -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 attention 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 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 expense as -a contribution to the work. To Dr. Carpenter 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 Palæozoic Protozoa; and Mr. Weston has aided greatly by the -preparation of slices for the microscope, 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. Carpenter; - Specimens from Long Lake; Additional - Structural Facts 76 - - Chapter V. Preservation of Eozoon 93 - Notes:--Hunt on Mineralogy of Eozoon; Silicified - Fossils in Silurian Limestones; Minerals - associated with Eozoon; Glauconites 115 - - Chapter VI. Contemporaries and Successors 127 - Notes:--On Stromatoporidæ; Localities of Eozoon 165 - - Chapter VII. Opponents and Objections 169 - Notes:--Objections and Replies; 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 ILLUSTRATIONS. - - -FULL PAGE ILLUSTRATIONS. - TO FACE - PAGE - - I. Cape Trinity, from a Photograph (_Frontispiece_). - - II. Map of the Laurentian Region 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. AmÅ“ba 60 - 13. Actinophrys 60 - 14. Entosolenia 62 - 15. Biloculina 62 - 16. Polystomella 62 - 17. Polymorphina 63 - 18. Archæospherinæ 67 - 19. Nummulites 73 - 20. Calcarina 73 - 21. Foraminiferal Rock-builders 75 - 21_a_. Casts of Cells of Eozoon 92 - 22. Modes of 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 111 - 31. Acervuline Variety of Eozoon 135 - 32, 33, 34. Archæospherinæ 137, 138 - 35. Annelid Burrows 140 - 36. Archæospherinæ 148 - 37. Eozoon Bavaricum 149 - 38, 39, 40. Archæocyathus 152, 153 - 41. Archæocyathus (Structure of) 154 - 42. Stromatopora 157 - 43. Stromatopora (Structure of) 158 - 44. Caunopora 159 - 45. CÅ“nostroma 160 - 46. Receptaculites 162 - 47, 48. Receptaculites (Structure of) 163 - 49. Laminæ of Eozoon 176 - - - - -THE DAWN OF LIFE. - - - - -CHAPTER I. - -INTRODUCTORY. - - -Every one has 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 introduced; 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 -impression that it would be the most appropriate way that the great -procession of animal existence should 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 successors? Can we do this by inference -from the succeeding types of being; and if so, do our anticipations -agree with any actual reality disinterred from the earth's crust? If we -could do this, either by inference or actual discovery, how strange it -would be to know that we had before us even the remains of the first -creature that could feel or will, and could place itself in vital -relation with the great powers of inanimate nature. If we believe in a -Creator, we shall feel it a solemn thing to have access to the first -creature into 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 themselves -to the dread alternatives of pain and mortality, must surely evoke -from us that filial reverence which we owe to the authors of our own -being, if they do not involuntarily draw forth even a superstitious -adoration. The veneration of the old Egyptian for his sacred animals -would be a comparatively reasonable idolatry, if we could imagine any -of these animals to have been the first that emerged from the domain -of dead matter, and the first link in a reproductive chain of being -that produced all the population of the world. Independently of any -such hypotheses, all students of nature must regard with surpassing -interest the first bright streaks of light that break on the long reign -of primeval night and death, and presage the busy day of teeming animal -existence. - -No wonder then that geologists have long and earnestly groped in the -rocky archives of the earth in search of some record of this patriarch -of the animal kingdom. But after long and patient research, there still -remained a large residuum of the oldest rocks, destitute of all traces -of living beings, and designated by the hopeless name "Azoic,"--the -formations destitute of remains of life, the stony records of a -lifeless world. So the matter remained till the Laurentian rocks of -Canada, lying at the base of these old 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 -receive it. It was regarded with feeble and not very intelligent faith -by many more, and was met with half-concealed or open scepticism by -others. It produced a copious crop of descriptive and controversial -literature, but for the most part technical, and confined to scientific -transactions and periodicals, read by very few except specialists. -Thus, few even of geological and biological students have clear ideas -of the real nature and mode of occurrence of these ancient organisms, -and of their relations to better known forms of life; while the crudest -and most inaccurate 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 animal -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 certain, -if properly entered into, to be fruitful of interesting 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 -adequately 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, account 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. -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 successors, 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 has 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 elementary manuals on geology, or "The -Story of the Earth and Man," by the writer of the present work. - -TABULAR VIEW OF THE EARTH'S GEOLOGICAL HISTORY. - - _Animal Kingdom._ _Geological Periods._ _Vegetable Kingdom._ - - Age of Man. CENOZOIC, OR Modern. Age of Angiosperms - NEOZOIC, OR Post-Pliocene, and Palms. - TERTIARY or Pleistocene. - Pliocene. - Miocene. - Age of Mammals. Eocene. - - Age of Reptiles. MESOZOIC Cretaceous. Age of Cycads and - Jurassic. Pines. - Triassic. - - Age of Amphibians PALÆOZOIC Permian. Age of Acrogens - and Fishes. Carboniferous. and Gymnosperms. - Erian, or Devonian. - Age of Mollusks, Upper Silurian. - Corals, and Lower Silurian, or - Crustaceans. Siluro-Cambrian. - Cambrian or - Primordial. Age of Algæ. - - Age of Protozoa, EOZOIC Huronian. Beginning of Age - and dawn of Upper Laurentian. of Algæ. - Animal Life. Lower Laurentian. - -[Illustration: - Plate II. - -MAP SHEWING THE DISTRIBUTION OF THE LAURENTIAN LIMESTONES HOLDING EOZOON - IN THE COUNTIES OF OTTAWA & ARGENTEUIL. - -_Drawn by M. R. Barlow_ _Stanford's Geog. Estab^t. Charing Cross, London._ - - Reprinted with additions from the Report of the Geology of Canada, - by Sir W. Logan, F.R.S., 1863.] - - - - -CHAPTER II. - -THE LAURENTIAN ROCKS. - - -As we descend in depth and time into the earth's crust, after passing -through nearly all the vast series of strata constituting the monuments -of geological history, we at length reach the Eozoic or Laurentian -rocks, deepest and oldest of all the formations known to the geologist, -and more thoroughly altered or metamorphosed by heat and heated -moisture than any others. These rocks, at one time known as Azoic, -being supposed destitute of all remains of living things, but now more -properly Eozoic, are those in which the first bright streaks of the -dawn of life make their appearance.[A] - -[Footnote A: Dana has recently proposed the term "_Archæan_," on the -ground that some of these rocks are as yet unfossiliferous but as the -oldest known part of them contains fossils, there seems no need for -this new name.] - -The name Laurentian, given originally to the Canadian development of -these rocks by Sir William Logan, but now applied to them throughout -the world, is derived from a range of hills lying north of the -St. Lawrence valley, which the old French geographers named the -Laurentides. In these hills the harder rocks of this old formation -rise to considerable heights, and form the highlands separating the -St. Lawrence valley from the great plain fronting on Hudson's Bay -and the Arctic Sea. At first sight it may seem strange that rocks so -ancient should anywhere appear at the surface, especially on the tops -of hills; but this is a necessary result of the mode of formation of -our continents. The most ancient sediments deposited in the sea were -those first elevated into land, and first altered and hardened by heat. -Upheaved in the folding of the earth's crust into high and rugged -ridges, they have either remained uncovered with newer sediments, or -have had such as were deposited on them washed away; and being of a -hard and resisting nature, they have remained comparatively unworn when -rocks much more modern have been swept off by denuding agencies. - -But the exposure of the old Laurentian skeleton of mother earth is not -confined to the Laurentide Hills, though these have given the formation -its name. The same ancient rocks appear in the Adirondack mountains -of New York, and in the patches which at lower levels protrude from -beneath the newer formations along the American coast from Newfoundland -to Maryland. The older gneisses of Norway, Sweden, and the Hebrides, -of Bavaria and Bohemia, belong to the same age, and it is not unlikely -that similar rocks in many other parts of the old continent will be -found to be of as great antiquity. In no part of the world, however, -are the Laurentian rocks more extensively distributed or better -known than in North America; and to this as the grandest and most -instructive development of them, and that which first afforded organic -remains, we may more especially devote our attention. Their general -relations to the other formations of America may be learned from the -rough generalised section (fig. 1); in which the crumpled and contorted -Laurentian strata of Canada are seen to underlie unconformably the -comparatively flat Silurian beds, which are themselves among the oldest -monuments of the geological history of the earth. - -[Illustration: Fig. 1. _General Section, showing the Relations of -the Laurentian and Palæozoic Rocks in Canada._ (L.) Laurentian. (1.) -Cambrian, or Primordial. (2.) Lower Silurian. (3.) Upper Silurian. (4.) -Devonian and Carboniferous.] - -The Laurentian rocks, associated with another series only a little -younger, the Huronian, form a great belt of broken and hilly country, -extending from Labrador across the north of Canada to Lake Superior, -and thence bending northward to the Arctic Sea. Everywhere on the lower -St. Lawrence they appear as ranges of billowy rounded ridges on the -north side of the river; and as viewed from the water or the southern -shore, especially when sunset deepens their tints to blue and violet, -they present a grand and massive appearance, which, in the eye of -the geologist, who knows that they have endured the battles and the -storms of time longer than any other mountains, invests them with a -dignity which their mere elevation 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, however, 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. - -[Illustration: Fig. 2. _Laurentian Hills opposite Kamouraska, Lower St. -Lawrence._ - -The islands in front are Primordial.] - -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 -agriculturist, except in the valleys, which follow the lines of its -softer beds, while it is a favourite region for the angler, the hunter, -and the lumberman. Many of the Laurentian townships of Canada are, -however, already extensively settled, and the traveller may pass -through a succession of more or less cultivated valleys, bounded by -rocks or wooded hills and crags, and diversified by running streams and -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 crystalline rocks, contorted in the most -remarkable manner, so that if they could be flattened out they would -serve as a skin much too large for mother earth in her present state, -so much has 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, consists of stratified -granitic rocks or gneisses, of indurated 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 with great beds of triclinic feldspar, -especially of that peculiar variety known as labradorite, or Labrador -feldspar, and which sometimes by its wonderful iridescent play of -colours becomes a beautiful ornamental stone. - -I cannot describe such rocks, but their names will tell something to -those who have any knowledge of the older crystalline materials of the -earth's crust. To those who have not, I would advise a visit to some -cliff on the lower St. Lawrence, or the Hebridean coasts, or the shore -of Norway, where the old hard crystalline and gnarled beds present -their sharp edges to the ever raging sea, and show their endless -alternations of various kinds and colours of strata often diversified -with veins and nests of crystalline minerals. He who has seen and -studied such a section of Laurentian rock cannot forget it. - -[Illustration: Fig. 3. _Section from Petite Nation Seigniory to St. -Jerome_ (60 miles). _After Sir W. E. Logan._ - -(_a, b._) Upper Laurentian. (_c._) Fourth gneiss. (_d´._) Third -limestone. (_d._) Third gneiss. (_e´._) Second limestone. (_x._) -Porphyry. (_y._) Granite.] - -All the constituents of the Laurentian series are in that state known -to geologists as metamorphic. They were once sandstones, clays, and -limestones, such as 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 observations of Sorby and of Hunt (the former in -connection with the microscopic structure of rocks, and the latter -in connection with the chemical conditions of change) show that no -very excessive amount of heat would be required. These observations -and those of Daubrée 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 alternations 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.) - -It is interesting to notice here that the Laurentian 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 previous 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 unlikely 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 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. - -[Illustration: Fig. 4. _The Laurentian Nucleus of the American -Continent._] - -Rocks 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, long -looked in vain for their actual discovery. Still, as astronomers have -suspected the existence of unknown 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 especially, have -committed themselves to such speculations. The reasons assigned may be -stated thus:-- - -Assuming the Laurentian rocks to be altered sediments, 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 geological age include thicker or more -extensive limestones. 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.[B] 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 -limestones of the later geological periods. Now, in later formations, -limestone is usually an organic rock, accumulated by the slow gathering -from the sea-water, or its plants, of calcareous matter, by corals, -foraminifera, 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 conformable -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 multitudes of animals of humble organization were accumulating -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 explained, or from the error of mistaking the true -bedded limestones for veins of calcareous spar. - -[Footnote B: Logan: _Geology of Canada_, p. 45.] - -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 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, unlikely a conclusion as that of -the existence of abundant animal and vegetable life in the Laurentian; -but the concurrence of the whole in a series of deposits unquestionably -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 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 Côte 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. -André 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 enormous pines, which constituted the original -forest. Half way we cross the Nation River, 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. André, 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 Côte 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. Love's original excavation, -whence some of the greater blocks containing Eozoon were taken, and a -larger opening made by an enterprising American on a vein of fibrous -serpentine, yielding "rock cotton," for packing steam pistons and -similar purposes. (Figs. 5 and 6.) - -[Illustration: Fig. 5. _Attitude of Limestone at St. Pierre._ - -(_a._) Gneiss band in the Limestone. (_b._) Limestone with Eozoon. -(_c._) Diorite and Gneiss.] - -[Illustration: Fig. 6. _Gneiss and Limestone at St. Pierre._ - -(_a._) Limestone. (_b._) Gneiss and Diorite.] - -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 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 laminæ of serpentine so -precisely like the _Stromatoporæ_ 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 palæontologists, 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 Côte St. Pierre are now in that collection and in my -own. A very fine example is represented, on a reduced scale, in Plate -III., which is taken from an original photograph.[C] In some of the -layers are found other and more minute fossils than Eozoon, 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 limestone. 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. - -[Footnote C: By Mr. Weston, of the Geological Survey of Canada.] - - -NOTES TO CHAPTER II. - - -(A.) Sir William E. Logan on the Laurentian 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 cannot be less - than 30,000 feet, and probably much exceeds it. The Laurentian of - the west of Scotland, according to Sir Roderick Murchison, also - attains a great thickness. In that region the Upper Laurentian or - Labrador series, has not yet been 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 Emmons, 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 formation, 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 Murchison, - turning his attention to this central European mass, placed it on the - same horizon. These rocks, underlying Barrande's Primordial zone, - with a great development 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 Gümbel 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, Gümbel and Crejci - account for its presence by an inverted fold in the strata; while - Sir Roderick places this at the base, and regards the whole as a - single series, in the normal fundamental position of the Laurentian - of Scotland and of Canada. 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 - contact. - - "The united thickness of these three great series may possibly - far surpass that of all the succeeding rocks from the base of the - Palæozoic 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 mechanical processes which have ever since been at - work disintegrating 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 crystalline 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 constitute 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 certainty either the base or the summit - of this series, these three may be conformably followed by many more. - Although the 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 existence of laminated - forms supposed to be organic in the Laurentian, by Sir W. E. Logan, - but before their structure and affinities had been ascertained, I - quote the following sentences:-- - - "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 oxidation, 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 containing rock. Sir William - Logan states[D] that 'the deposits 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 disseminated 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 corrugated 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 it as possible that it - may have been in a state of aqueous solution;[E] 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. - -[Footnote D: _Geology of Canada_, 1863.] - -[Footnote E: _Report of the Geological Survey of Canada_, 1866.] - - "The quantity of graphite in the Lower Laurentian series is enormous. - In a recent visit to the township of Buckingham, on the Ottawa - River, 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 extent 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.[F] - -[Footnote F: Matthew, in _Quart. Journ. Geol. Soc._, vol. xxi., p. 423. -_Acadian Geology_, p. 662.] - - "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 cases, in the first - instance, from the deoxidation of carbonic acid by living plants. No - other source of carbon can, I believe, be imagined in the Laurentian - period. We may, however, suppose either that the graphitic matter - of the Laurentian 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 Rhode Island. These - instances, however, are exceptional, and the greater part of the - disseminated and vein graphite might rather be compared in its mode - of occurrence 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 metamorphosed and converted into - graphitic rocks not dissimilar to those in the less altered portions - of the Laurentian.[G] 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 resistance, 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 Dorchester and - Hillsborough, New Brunswick, with an arrangement 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 transverse columnar structure, and regarded by - Logan and Hunt as an altered bitumen. These palæozoic 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 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. - -[Footnote G: Granby, Melbourne, Owl's Head, etc., _Geology of Canada_, -1863, p. 599.] - - "Dr. Hunt has, however, observed an indication of terrestrial - vegetation, or at least of subaërial 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 Newborough, 200 feet thick,[H] 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. - -[Footnote H: _Geology of Canada_, 1863.] - - "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, algæ - have been converted into bituminous matter, we cannot ordinarily - obtain any structural evidence 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 - bituminous 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, sometimes of much beauty. In correspondence - with this, while in some Laurentian graphitic rocks, as, for - instance, in the compact 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 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 palæozoic 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 - ouangondianum_) 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.[I] No structures so perfect have as yet been detected - in the Laurentian, though in the largest of the three graphitic beds - at St. John there appear to be fibrous structures which I believe may - indicate the existence of land-plants. This graphite is composed of - contorted and slickensided laminæ, 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. - -[Footnote I: _Acadian Geology_, p. 535. In calcified specimens the -structures remain in the graphite after decalcification by an acid.] - - "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 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 Algæ. - - "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 structure of the substance - corresponds with that of the carbonaceous 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 existed 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 Rocks, etc. - - In the map of the Laurentian nucleus of America (fig. 4,) I have - not inserted the Laurentian rocks believed to exist in the Rocky - Mountains and other western ranges. Their distribution 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 Laurentian 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 sectional - 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 unconformably on these, others corresponding to the Upper - Laurentian; 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. Hayden's report describes granitic - and gneissose rocks, probably 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 particles 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.) - -[Illustration: - Plate III. - - From a Photo by Weston. Vincent Brooks, Day & Son, Lith. - - WEATHERED SPECIMEN OF EOZOON CANADENSE. - (ONE-HALF NATURAL SIZE.) - - _To face Chap. 3_] - - - - -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 before 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 examination of the rocks and minerals -by Dr. Sterry Hunt. On the other hand, Dr. Carpenter and others in -England 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 dissimilar branches -of scientific inquiry were destined to be united by a series of happy -discoveries, made not fortuitously 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 -zoological and palæontological knowledge, and the surveys previously -made, whereby the age and distribution of the Laurentian rocks and -the chemical conditions of their deposition and metamorphism were -ascertained. - -[Illustration: Fig. 7. _Eozoon mineralized by Loganite and Dolomite._ - -(Collected by Dr. Wilson, of Perth.)] - -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 laminæ of a dark green mineral 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 -pyroxene, 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 seem to have at once struck Sir W. E. Logan -as resembling the Silurian fossils known as _Stromatopora_, and he -showed them to Mr. Billings, the palæontologist of the survey, and to -the writer, with this suggestion, 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 affirming -the organic nature of such specimens; and my own suggestion was that -they should be sliced, and examined microscopically, and that if -fossils, as they presented merely concentric laminæ 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 Laurentian 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 -Report of the Geological Survey, summing up its work to that time, -was published, under the name of the _Geology of Canada_, and in this, -at page 49, will be found two figures of one of the Calumet specimens, -here reproduced, and which, though unaccompanied with any specific -name or technical description, were referred to as probably Laurentian -fossils. (Figs. 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 -exception to this, stating that though in the slices before examined -no structure was apparent, still my impression was that the calcareous -matter was the fossil, and the serpentine or loganite the filling. He -said--"In that case, would it not be well to re-examine the specimens, -and 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 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 specimens -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 representation of the first seen group of canals penetrated by -serpentine. - -[Illustration: Fig. 8. _Weathered Specimen of Eozoon from the Calumet._ - -(Collected by Mr. McMullen.)] - -[Illustration: Fig. 9. _Cross Section of the Specimen represented in -Fig. 8._ - -The dark parts are the laminæ of calcareous matter converging to the -outer surface.] - -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 examining the typical specimens of Eozoon, but had -slices prepared of every variety of Laurentian limestone, of altered -limestones from the Primordial and Silurian, and of serpentine -marbles of all the varieties furnished by our collections. These were -examined with ordinary 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; -and of some of the more important structures beautiful drawings -were executed by the late Mr. H. S. Smith, the then palæontological -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 occurring in these or other limestones. - -[Illustration: Fig. 10. _Group of Canals in the Supplemental Skeleton -of Eozoon._ - -Taken from the specimen in which they were first recognised. -Magnified.] - -At this stage of the matter, and after exhibiting to Sir William all -the characteristic appearances in comparison with such concretionary, -dendritic, and crystalline structures as most resembled them, and also -with the structure of recent and fossil Foraminifera, I suggested that -the further prosecution of the matter should be handed over to Mr. -Billings, as palæontologist 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 appearances of Foraminifera or of mineral -substances. It was finally arranged that I should prepare a description -of the fossil, which Sir William would take to London, along with Dr. -Hunt's notes, the more important 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 cell-wall, which I had not -observed previously through a curious accident as to specimens.[J] Mr. -Lowe had been sent back to the Ottawa to explore, and just before Sir -William's departure had sent in some specimens from a new locality at -Petite Nation, similar in general appearance to those from Grenville, -which Sir 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 Grenville specimens, and which I did -not see until after it had been detected by Dr. Carpenter in London. -Dr. Carpenter thus contributed in a very important manner to the -perfecting of the investigations begun in Canada, and on him has fallen -the greater part of their illustration and defence,[K] 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. - -[Footnote J: In papers by Dr. Carpenter, subsequently referred to. -Prof. Jones published an able exposition of the facts in the _Popular -Science Monthly_.] - -[Footnote K: In _Quarterly Journal of Geological Society_, vol. xxii.; -_Proc. Royal Society_, vol. xv.; _Intellectual Observer_, 1865. _Annals -and Magazine of Natural History_, 1874; and other papers and notices.] - -[Illustration: 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.] - -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, palæontology, and mineralogy of _Eozoon -Canadense_ and its containing rocks were first given to the world.[L] -It cannot be wondered at that when geologists and palæontologists were -thus required to believe in the existence of organic remains in rocks -regarded as altogether Azoic and hopelessly barren of fossils, and -to carry back the dawn of life as far before those Primordial rocks, -which were supposed to contain its first traces, as these are before -the middle period of the earth's life history, some 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 types of animals, and of the conditions of mineralization -of organic remains, possessed by few even of professional 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. - -[Footnote L: _Journal Geological Society_, February, 1865.] - -"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 Palæozoic -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 comparatively 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 extension 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 specimens in -the Upper Laurentian or Huronian of Tudor. Gümbel recognised the -organism in Laurentian Rocks in Bavaria and elsewhere in Europe, and -discovered a new species in the Huronian of Bavaria.[M] Eozoon was -recognised in Laurentian limestones in Massachusetts[N] and New York, -and there has been a rapid growth of new facts increasing our knowledge -of Foraminifera of similar types in the succeeding Palæozoic 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 vindication 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 specimens 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-examine the locality -at Petite Nation originally discovered by Mr. Lowe, and am prepared to -show that all the facts with reference to the mode of occurrence of -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. - -[Footnote M: _Ueber das Vorkommen von Eozoon_, 1866.] - -[Footnote N: By Mr. Bicknell at Newbury, and Mr. Burbank at Chelmsford. -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 Chelmsford specimens and in those of Warren, New -York, is in small and rare fragments in serpentinous limestone.] - -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 accumulations 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 affinities 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 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 Laurentian 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 latter are when compared with modern -forests? - - -NOTES TO CHAPTER III. - - -(A.) Sir William E. Logan on the Discovery and 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 limestones did not seem to offer a proof in - the negative, any more than their undiscovered presence in newer - crystalline limestones 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, has 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;[O] 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 Geological Survey of the province, from one of the limestones of - the Laurentian series occurring at the Grand Calumet, on the river - Ottawa. - -[Footnote O: _Quarterly Journal of the Geological Society_, xv., 493.] - - "Any organic remains which may have been entombed in these limestones - would, if they retained their calcareous character, 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 concentric 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 the 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 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 accidentally observed indications of - similar forms in blocks of Laurentian 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 microscope, the minute structure was observed in the first - one submitted to inspection. At the request of Mr. Billings, the - palæontologist 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 communication. 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 Foraminifer, 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 - resembling 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, serpentine, 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 consecutive stages of a continuous process. In - the Burgess specimens, while the sarcode is replaced by loganite, the - calcareous skeleton, as has already been stated, has been replaced - by dolomite, 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 Foraminifera, and - that of the allied forms in Tertiary and recent deposits (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 overlying 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 - limestone, 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 irregular masses of - white crystalline pyroxene, some of them twenty yards in length by - four or five wide. They appear to be confusedly 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 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 - perhaps more. Other parts, immediately on the outside of the sheet of - serpentine, are occupied with about the same thickness of what appear - to be the ruins of the fossil, broken up into a more or less granular - mixture of calc-spar and serpentine, 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 disseminated 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 portion, 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-serpentinous 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 recent 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. 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 examination 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 specimens 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 - limestone, white coarsely granular limestone, and bands of dark - bluish compact limestone and black pyritiferous slates, to the whole - of which Mr. Vennor 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 appended, 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 therefore supposed - that the Hastings series may be somewhat 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 anorthosite - 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 outline - 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 specimen 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 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 Grenville 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 Côte 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 Côte 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 limestone, which has - somewhat the aspect of a conglomerate, specimens have been obtained - resembling some of the figures given by Gümbel 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 Côte 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 - bruising. There is little doubt that these portions of the skeleton - are partially replaced by dolomite, as more recent fossils are - 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 investigation of the locality some spots will be found - to yield specimens in which the calcareous skeleton still exists - unreplaced 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 Côte 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 Laurentian 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 minerals, pyroxene and serpentine. Now we have it imbedded - in limestone, just as most fossils are. In every case, with the - exception 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, therefore, 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 organism have been made by - Professors King and Rowney: but these appear to me to be based upon - the supposition that because 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 Rowney passed in review before him - prior to his coming to the conclusions which he has published." - -_Ascending Section of the Eozoic Rocks in the County of Hastings, -Ontario._ By Mr. H. G. Vennor. - - Feet. - 1. Reddish and flesh-coloured granitic gneiss, the thickness - of which is unknown; estimated at not less than 2,000 - - 2. Grayish and flesh-coloured gneiss, sometimes hornblendic, - 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, including - lenticular patches of quartz, and broken and - contorted layers of quartzo-felspathic rock, rarely above - a few inches in thickness. This limestone, which includes - in Elzivir a one-foot bed of graphite, is sometimes - very thin, but in other places attains a thickness - of 750 feet; estimated as averaging 400 - - 4. Hornblendic and dioritic rocks, massive or schistose, - 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 - 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 ferruginous, - 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 fined-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 interstratified beds of silicious - limestone, and, like the last division, weathering rusty - brown 1,900 - - 9. Gray micaceous limestone, sometimes plumbaginous, - 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 1,100 - - 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 - -[Illustration: - 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.] - -[Illustration: Fig. 12. _AmÅ“ba._ Fig. 13. _Actinophrys._ - -From original sketches.] - - - - -CHAPTER IV. - -WHAT IS EOZOON? - - -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 _AmÅ“ba_[P] (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 pseudopods which serve as -extempore limbs. When moving on the surface of a slip of glass under -the microscope, it seems, as it were, to flow along rather than creep, -and its body appears to be of a semi-fluid consistency. It may be taken -as an example of the least complex forms of animal life known to us, -and is often spoken of by naturalists as if it were merely a little -particle of living and scarcely organized jelly or protoplasm. When -minutely examined, however, it will not be found so simple as it at -first sight appears. Its outer layer 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, which is a little cell capable, at certain -times, of producing by its division new individuals. Food when taken -in through the wall of the body forms little pellets, which become -surrounded by a digestive liquid exuded from the enclosing mass into -rounded cavities or extemporised stomachs. Minute granules are seen -to circulate in the gelatinous interior, and may be substitutes for -blood-cells, and the outer layer of the body is capable of protrusion -in any direction into long processes, which are very mobile, and used -for locomotion and prehension. Further, this creature, though destitute -of most of the parts which we are accustomed to regard as proper to -animals, seems to exercise volition, 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 AmÅ“ba are found other types of equally simple Protozoa, but -somewhat differently organized. One of these, _Actinophrys_ (fig. 13), -has the body globular and unchanging in form, the outer wall of greater -thickness; the pulsating vesicle like a blister on the surface, and the -pseudopods long and thread-like. Its habits are similar to those of the -AmÅ“ba, and I introduce it to show the variations of form and structure -possible even among these simple creatures. - -[Footnote P: The alternating animal, alluding to its change of form.] - -[Illustration: Fig. 14. _Entosolenia._ - -A one-celled Foraminifer. Magnified as a transparent object.] - -[Illustration: Fig. 15. _Biloculina._ - -A many-chambered Foraminifer. Magnified as a transparent object.] - -[Illustration: Fig. 16. _Polystomella._ - -A spiral Foraminifer. Magnified as an opaque object.] - -The AmÅ“ba 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 addition multitudes -of microscopic pores through which the soft gelatinous matter can ooze, -and form outside finger-like or thread-like extensions for collecting -food. In some cases the shell consists of a single cavity only, but in -most, after one cell is completed, others are added, forming a series -of cells or chambers communicating with each other, and often arranged -spirally or otherwise in most beautiful and symmetrical forms. Some of -these creatures, usually named Foraminifera, are locomotive, others -sessile and attached. Most of them are microscopic, but some grow by -multiplication of chambers till they are a quarter of an inch or more -in breadth. (Figs. 14 to 17.) - -[Illustration: Fig. 17. _Polymorphina._ - -A many-chambered Foraminifer. Magnified as an opaque object. Figs. 14 -to 17 are from original sketches of Post-pliocene specimens.] - -The original skeleton or primary cell-wall of most of these creatures -is seen under the microscope to be perforated with innumerable pores, -and is extremely thin. When, however, owing to the increased size of -the shell, or other wants of the creature, it is necessary to give -strength, this is done by adding new portions of carbonate of lime to -the outside, and to these Dr. Carpenter has given the appropriate name -of "supplemental skeleton;" and this, when covered by new growths, -becomes what he has termed an "intermediate skeleton." 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 microscopic 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 accumulation takes place we learn from what is now going on -in the ocean, more especially from the result of the recent deep-sea -dredging expeditions. The Foraminifera are vastly numerous, both near -the 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 hardened into limestone. This process is now depositing a great -thickness of white ooze in the bottom of the ocean; and in times past -it has produced such vast thicknesses of calcareous matter as the chalk -and the nummulitic limestone of Europe and the orbitoidal 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 meantime we shall see what claims -Eozoon has to be included 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 -crystalline marble, the cavities of the cells by green serpentine, the -mode of whose introduction we shall have to consider in the sequel. -The lowest layer of 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 Huxley the name _Bathybius_, 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, -perforated by innumerable minute tubuli, and by some larger pores or -septal orifices, while supported at intervals 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 successive 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" manner, and with very thin walls -unprotected by supplemental skeleton. Then the growth was arrested, -and possibly these upper layers gave off reproductive germs, fitted -to float or swim away and to establish new colonies. We may have -such reproductive germs in certain curious globular bodies, like -loose cells, found in connection with irregular Eozoon in one of -the Laurentian limestones at Long Lake and elsewhere. These curious -organisms I observed some years ago, but no description of them was -published at the time, as I hoped to obtain better examples. I now -figure some of them, and give their description in a note. (Fig. 18). -I have recently obtained numerous additional examples from the beds -holding Eozoon at St. Pierre, on the Ottawa. They occur at this place -on the surface of layers of the limestone in vast numbers, as if they -had been growing separately on the bottom, or had been drifted over -it by currents. These we shall further discuss hereafter. Such was -the general mode of growth of Eozoon, and we may now consider more in -detail some questions as to its gigantic size, its precise mode of -nutrition, the arrangement of its parts, its relations to more modern -forms, and the effects of its growth in the Laurentian seas. In the -meantime a study of our illustration, Plate IV., which is intended as a -magnified restoration of the animal, will enable the reader distinctly -to understand its structure and probable mode of growth, and to avail -himself intelligently of the partial representations of its fossilized -remains in the other plates and woodcuts. - -[Illustration: 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. (_d._) Serpentine cast of a -similar chamber, decalcified, and showing casts of tubuli.] - -With respect to its size, we shall find in a subsequent chapter that -this was rivalled by some succeeding animals of the same humble type -in the Silurian age; and that, as a whole, foraminiferal animals have -been diminishing in size in the lapse of geological time. It is indeed -a fact of so frequent occurrence that it may almost be regarded as -a law of the introduction of new forms of life, that they assume in -their early history gigantic dimensions, and are afterwards continued -by less magnificent species. The relations of this to external -conditions, in the case of higher animals, are often complex and -difficult to understand; but in organisms so low as Eozoon and its -allies, they lie more on the surface. Such creatures may be regarded -as the simplest and most ready media for the conversion of vegetable -matter into animal tissues, and their functions are almost entirely -limited to those of nutrition. Hence it is likely that they will be -able to appear in the most gigantic forms under such conditions as -afford them the greatest amount of pabulum for the nourishment of -their soft parts and for their skeletons. There is reason to believe, -for example, that the occurrence, both in the chalk and the deep-sea -mud, of immense quantities of the minute bodies known as Coccoliths -along with Foraminifera, is not accidental. The Coccoliths appear to -be grains of calcareous matter formed in minute plants adapted to a -deep-sea habitat; and these, along with the vegetable and animal debris -constantly being derived from the death of the living things at the -surface, afford the material both of sarcode and shell. Now if the -Laurentian graphite represents an exuberance of vegetable growth in -those old seas proportionate to the great supplies of carbonic acid -in the atmosphere and in the waters, and if the Eozoic ocean was even -better supplied with carbonate of lime than those Silurian seas whose -vast limestones bear testimony to their richness in such material, we -can easily imagine that the conditions may have been more favourable -to a creature like Eozoon than those of any other period of geological -time. - -Growing, as Eozoon did, on the floor of the ocean, and covering wide -patches with more or less irregular masses, it must have thrown up from -its whole surface its pseudopods to seize whatever floating particles -of food the waters carried over it. There is also reason to believe, -from the outline of certain specimens, that it often grew upward in -cylindrical or club-shaped forms, and that the broader patches were -penetrated by large pits or oscula, admitting the sea-water deeply into -the substance of the masses. In this way its growth might be rapid and -continuous; but it does not seem to have possessed the power of growing -indefinitely by new and living layers covering those that had died, -in the manner of some corals. Its life seems to have had a definite -termination, and when that was reached an entirely new colony had to -be commenced. In this it had more affinity with the Foraminifera, as -we now know them, than with the corals, though practically it had the -same power with the coral polyps of accumulating limestone in the sea -bottom, a power indeed still possessed by its foraminiferal successors. -In the case of coral limestones, we know that a large proportion of -these consist not of continuous reefs but of fragments of coral mixed -with other calcareous organisms, spread usually by waves and currents -in continuous beds over the sea bottom. In like manner we find in -the limestones containing Eozoon, layers of fragmental matter which -shows in places the characteristic structures, and which evidently -represents the debris swept from the Eozoic masses and reefs by the -action of the waves. It is with this fragmental matter that the small -rounded organisms already referred to most frequently occur; and while -they may be distinct animals, they may also be the fry of Eozoon, or -small portions of its acervuline upper surface floated off in a living -state, and possibly capable of living independently and of founding new -colonies. - -It is only by a somewhat wild poetical licence that Eozoon has been -represented as a "kind of enormous composite animal stretching from the -shores of Labrador to Lake Superior, and thence northward and southward -to an unknown distance, and forming masses 1500 feet in depth." We may -discuss by-and-by the question of the composite nature of masses of -Eozoon, and we see in the corals evidence of the great size to which -composite animals of a higher grade can attain. In the case of Eozoon -we must imagine an ocean floor more uniform and level than that now -existing. On this the organism would establish itself in spots and -patches. These might finally become confluent over large areas, just -as massive corals do. As individual masses attained maturity and died, -their pores would be filled up with limestone or silicious deposits, -and thus could form a solid basis for new generations, and in this way -limestone to an indefinite extent might be produced. Further, wherever -such masses were high enough to be attacked by the breakers, or where -portions of the sea bottom were elevated, the more fragile parts of the -surface would be broken up and scattered widely in beds of fragments -over the bottom of the sea, while here and there beds of mud or sand -or of volcanic debris would be deposited over the living or dead -organic mass, and would form the layers of gneiss and other schistose -rocks interstratified with the Laurentian limestone. In this way, in -short, Eozoon would perform a function combining that which corals and -Foraminifera perform in the modern seas; forming both reef limestones -and extensive chalky beds, and probably living both in the shallow and -the deeper parts of the ocean. If in connection with this we consider -the rapidity with which the soft, simple, and almost structureless -sarcode of these Protozoa can be built up, and the probability that -they were more abundantly supplied with food, both for nourishing their -soft parts and skeletons, than any similar creatures in later times, we -can readily understand the great volume and extent of the Laurentian -limestones which they aided in producing. I say aided in producing, -because I would not desire to commit myself to the doctrine that the -Laurentian limestones are wholly of this origin. There may have been -other animal limestone-builders than Eozoon, and there may have been -limestones formed by plants like the modern Nullipores or by merely -mineral deposition. - -[Illustration: Fig. 19. _Section of a Nummulite, from Eocene Limestone -of Syria._ - -Showing chambers, tubuli, and canals. Compare this and fig. 20 with -figs. 10 and 11.] - -[Illustration: Fig. 20. _Portion of shell of Calcarina._ - -Magnified, after Carpenter. (_a._) Cells. (_b._) Original cell-wall -with tubuli. (_c._) Supplementary skeleton with canals.] - -Its relations to modern animals of its type have been very clearly -defined by Dr. Carpenter. In the structure of its proper wall and its -fine parallel perforations, it resembles the _Nummulites_ and their -allies; and the organism may therefore be regarded as an aberrant -member of the Nummuline group, which affords some of the largest and -most widely distributed of the fossil Foraminifera. This resemblance -may be seen in fig. 19. To the Nummulites it also conforms in its -tendency to form a supplemental or intermediate skeleton with canals, -though the canals themselves in their arrangement more nearly resemble -Calcarina, which is represented in fig. 20. In its superposition of -many layers, and in its tendency to a heaped up or acervuline irregular -growth it resembles _Polytrema_ and _Tinoporus_, forms of a different -group in so far as shell-structure is concerned. It may thus be -regarded as a composite type, combining peculiarities now observed in -two groups, or it may be regarded as a representative in the Nummuline -series of Polytrema and Tinoporus in the Rotaline series. At the time -when Dr. Carpenter stated these affinities, it might be objected that -Foraminifera of these families are in the main found in the Modern and -Tertiary periods. Dr. Carpenter has since shown that the curious oval -Foraminifer called _Fusulina_, found in the coal formation, is in like -manner allied to both Nummulites and Rotalines; and still more recently -Mr. Brady has discovered a true Nummulite in the Lower Carboniferous of -Belgium. This group being now fairly brought down to the Palæozoic, we -may hope finally to trace it back to the Primordial, and thus to bring -it still nearer to Eozoon in time. - -[Illustration: Fig. 21. _Foraminiferal Rock Builders._ - -(_a._) Nummulites lævigata--Eocene. (_b._) The same, showing chambered -interior. (_c._) Milioline limestone, magnified--Eocene, Paris. (_d._) -Hard Chalk, section magnified--Cretaceous.] - -Though Eozoon was probably not the only animal of the Laurentian seas, -yet it was in all likelihood the most conspicuous and important as -a collector of calcareous matter, filling the same place afterwards -occupied by the reef-building corals. Though probably less efficient -than these as a constructor of solid limestones, from its less -permanent and continuous growth, it formed wide floors and patches -on the sea-bottom, and when these were broken up vast quantities of -limestone were formed from their debris. It must also be borne in mind -that Eozoon was not everywhere infiltrated with serpentine or other -silicious minerals; quantities of its substance were merely filled -with carbonate of lime, resembling the chamber-wall so closely that -it is nearly impossible to make out the difference, and thus is likely -to pass altogether unobserved by collectors, and to baffle even the -microscopist. (Fig. 24.) Although therefore the layers which contain -well characterized Eozoon are few and far between, there is reason to -believe that in the composition of the limestones of the Laurentian -it bore no small part, and as these limestones are some of them -several hundreds of feet in thickness, and extend over vast areas, -Eozoon may be supposed to have been as efficient a world-builder as -the Stromatoporæ of the Silurian and Devonian, the Globigerinæ and -their allies in the chalk, or the Nummulites and Miliolites in the -Eocene. The two latter groups of rock-makers are represented in our -cut, fig. 21; the first will engage our attention in chapter sixth. It -is a remarkable illustration of the constancy of natural causes and of -the persistence of animal types, that these humble Protozoans, which -began to secrete calcareous matter in the Laurentian period, have been -continuing their work in the ocean through all the geological ages, -and are still busy in accumulating those chalky muds with which recent -dredging operations in the deep sea have made us so familiar. - - -NOTES TO CHAPTER IV. - - -(A.) Original Description of Eozoon Canadense. - -[As given by the author in the _Journal of the Geological Society_, -February, 1865.] - - "At the request of Sir W. E. Logan, I have submitted to microscopic - examination slices of certain peculiar laminated forms, consisting - of alternate layers of carbonate of lime and serpentine, and of - carbonate of lime and white pyroxene, found in the Laurentian - limestone of Canada, and regarded by Sir William as possibly fossils. - I have also examined slices of a large number of limestones from the - Laurentian series, not showing the forms of these supposed fossils. - - "The specimens first mentioned are masses, often several inches in - diameter, presenting to the naked eye alternate laminæ of serpentine, - or of pyroxene, and carbonate of lime. Their general aspect, as - remarked by Sir W. E. Logan (_Geology of Canada_, 1863, p. 49), - reminds the observer of that of the Silurian corals of the genus - Stromatopora, except that the laminæ diverge from and approach each - other, and frequently anastomose or are connected by transverse septa. - - "Under the microscope the resemblance to Stromatopora is seen to - be in general form merely, and no trace appears of the radiating - pillars characteristic of that genus. The laminæ of serpentine and - pyroxene present no organic structure, and the latter mineral is - highly crystalline. The laminæ of carbonate of lime, on the contrary, - retain distinct traces of structures which cannot be of a crystalline - or concretionary character. They constitute parallel or concentric - partitions of variable thickness, enclosing flattened spaces or - chambers, frequently crossed by transverse plates or septa, in some - places so numerous as to give a vesicular appearance, in others - occurring only at rare intervals. The laminæ themselves are excavated - on their sides into rounded pits, and are in some places traversed by - canals, or contain secondary rounded cells, apparently isolated. In - addition to these general appearances, the substance of the laminæ, - where most perfectly preserved, is seen to present a fine granular - structure, and to be penetrated by numerous minute tubuli, which - are arranged in bundles of great beauty and complexity, diverging - in sheaf-like forms, and in their finer extensions anastomosing so - as to form a network (figs. 10 and 28). In transverse sections, and - under high powers, the tubuli are seen to be circular in outline, and - sharply defined (fig. 29). In longitudinal sections, they sometimes - present a beaded or jointed appearance. Even where the tubular - structure is least perfectly preserved, traces of it can still be - seen in most of the slices, though there are places in which the - laminæ are perfectly compact, and perhaps were so originally. - - "With respect to the nature and probable origin of the appearances - above described, I would make the following remarks:-- - - "1. The serpentine and pyroxene which fill the cavities of the - calcareous matter have no appearance of concretionary structure. - On the contrary, their aspect is that of matter introduced by - infiltration, or as sediment, and filling spaces previously existing. - In other words, the calcareous matter has not been moulded on the - forms of the serpentine and augite, but these have filled spaces - or chambers in a hard calcareous mass. This conclusion is further - confirmed by the fact, to be referred to in the sequel, that the - serpentine includes multitudes of minute foreign bodies, while the - calcareous matter is uniform and homogeneous. It is also to be - observed that small veins of carbonate of lime occasionally traverse - the specimen's, and in their entire absence of structures other than - crystalline, present a striking contrast to the supposed fossils. - - "2. Though the calcareous laminæ have in places a crystalline - cleavage, their forms and structures have no relation to this. Their - cells and canals are rounded, and have smooth walls, which are - occasionally lined with films apparently of carbonaceous matter. - Above all, the minute tubuli are different from anything likely to - occur in merely crystalline calc-spar. While in such rocks little - importance might be attached to external forms simulating the - appearances of corals, sponges, or other organisms, these delicate - internal structures have a much higher claim to attention. Nor is - there any improbability in the preservation of such minute parts in - rocks so highly crystalline, since it is a circumstance of frequent - occurrence in the microscopic examination of fossils that the finest - structures are visible in specimens in which the general form and the - arrangement of parts have been obliterated. It is also to be observed - that the structure of the calcareous laminæ is the same, whether the - intervening spaces are filled with serpentine or with pyroxene. - - "3. The structures above described are not merely definite and - uniform, but they are of a kind proper to animal organisms, and - more especially to one particular type of animal life, as likely as - any other to occur under such circumstances: I refer to that of the - Rhizopods of the order Foraminifera. The most important point of - difference is in the great size and compact habit of growth of the - specimens in question; but there seems no good reason to maintain - that Foraminifera must necessarily be of small size, more especially - since forms of considerable magnitude referred to this type are known - in the Lower Silurian. Professor Hall has described specimens of - Receptaculites twelve inches in diameter; and the fossils from the - Potsdam formation of Labrador, referred by Mr. Billings to the genus - Archæocyathus, are examples of Protozoa with calcareous skeletons - scarcely inferior in their massive style of growth to the forms now - under consideration. - - "These reasons are, I think, sufficient to justify me in regarding - these remarkable structures as truly organic, and in searching for - their nearest allies among the Foraminifera. - - "Supposing then that the spaces between the calcareous laminæ, as - well as the canals and tubuli traversing their substance, were once - filled with the sarcode body of a Rhizopod, comparisons with modern - forms at once suggest themselves. - - "From the polished specimens in the Museum of the Canadian Geological - Survey, it appears certain that these bodies were sessile by a broad - base, and grew by the addition of successive layers of chambers - separated by calcareous laminæ, but communicating with each other by - canals or septal orifices sparsely and irregularly distributed. Small - specimens have thus much the aspect of the modern genera Carpenteria - and Polytrema. Like the first of these genera, there would also seem - to have been a tendency to leave in the midst of the structure a - large central canal, or deep funnel-shaped or cylindrical opening, - for communication with the sea-water. Where the laminæ coalesce, and - the structure becomes more vesicular, it assumes the 'acervuline' - character seen in such modern forms as Nubecularia. - - "Still the magnitude of these fossils is enormous when compared with - the species of the genera above named; and from the specimens in the - larger slabs from Grenville, in the museum of the Canadian Survey, - it would seem that these organisms grew in groups, which ultimately - coalesced, and formed large masses penetrated by deep irregular - canals; and that they continued to grow at the surface, while the - lower parts became dead and were filled up with infiltrated matter or - sediment. In short, we have to imagine an organism having the habit - of growth of Carpenteria, but attaining to an enormous size, and by - the aggregation of individuals assuming the aspect of a coral reef. - - "The complicated systems of tubuli in the Laurentian fossil indicate, - however, a more complex structure than that of any of the forms - mentioned above. I have carefully compared these with the similar - structures in the 'supplementary skeleton' (or the shell-substance - that carries the vascular system) of Calcarina and other forms, and - can detect no difference except in the somewhat coarser texture of - the tubuli in the Laurentian specimens. It accords well with the - great dimensions of these, that they should thus thicken their walls - with an extensive deposit of tubulated calcareous matter; and from - the frequency of the bundles of tubuli, as well as from the thickness - of the partitions, I have no doubt that all the successive walls, as - they were formed, were thickened in this manner, just as in so many - of the higher genera of more modern Foraminifera. - - "It is proper to add that no spicules, or other structures indicating - affinity to the Sponges, have been detected in any of the specimens. - - "As it is convenient to have a name to designate these forms, I - would propose that of Eozoon, which will be specially appropriate to - what seems to be the characteristic fossil of a group of rocks which - must now be named Eozoic rather than Azoic. For the species above - described, the specific name of Canadense has been proposed. It may - be distinguished by the following characters:-- - - "Eozoon Canadense; _gen. et spec. nov._ - - "_General form._--Massive, in large sessile patches or irregular - cylinders, growing at the surface by the addition of successive - laminæ. - - "_Internal structure._--Chambers large, flattened, irregular, with - numerous rounded extensions, and separated by walls of variable - thickness, which are penetrated by septal orifices irregularly - disposed. Thicker parts of the walls with bundles of fine branching - tubuli. - - "These characters refer specially to the specimens from Grenville and - the Calumet. There are others from Perth, C. W., which show more - regular laminæ, and in which the tubuli have not yet been observed; - and a specimen from Burgess, C. W., contains some fragments of laminæ - which exhibit, on one side, a series of fine parallel tubuli like - those of Nummulina. These specimens may indicate distinct species; - but on the other hand, their peculiarities may depend on different - states of preservation. - - "With respect to this last point, it may be remarked that some of - the specimens from Grenville and the Calumet show the structure of - the laminæ with nearly equal distinctness, whether the chambers are - filled with serpentine or pyroxene, and that even the minute tubuli - are penetrated and filled with these minerals. On the other hand, - there are large specimens in the collection of the Canadian Survey - in which the lower and still parts of the organism are imperfectly - preserved in pyroxene, while the upper parts are more perfectly - mineralized with serpentine." - - * * * * * - - [The following note was added in a reprint of the paper in the - _Canadian Naturalist_, April, 1865.] - - "Since the above was written, thick slices of Eozoon from Grenville - have been prepared, and submitted to the action of hydrochloric acid - until the carbonate of lime was removed. The serpentine then remains - as a cast of the interior of the chambers, showing the form of their - original sarcode-contents. The minute tubuli are found also to have - been filled with a substance insoluble in the acid, so that casts - of these also remain in great perfection, and allow their general - distribution to be much better seen than in the transparent slices - previously prepared. These interesting preparations establish the - following additional structural points:-- - - "1. That the whole mass of sarcode throughout the organism was - continuous; the apparently detached secondary chambers being, as - I had previously suspected, connected with the larger chambers by - canals filled with sarcode. - - "2. That some of the irregular portions without lamination are not - fragmentary, but due to the acervuline growth of the animal; and that - this irregularity has been produced in part by the formation of - projecting patches of supplementary skeleton, penetrated by beautiful - systems of tubuli. These groups of tubuli are in some places very - regular, and have in their axes cylinders of compact calcareous - matter. Some parts of the specimens present arrangements of this kind - as symmetrical as in any modern Foraminiferal shell. - - "3. That all except the very thinnest portions of the walls of - the chambers present traces, more or less distinct, of a tubular - structure. - - "4. These facts place in more strong contrast the structure of - the regularly laminated species from Burgess, which do not show - tubuli, and that of the Grenville specimens, less regularly - laminated and tubulous throughout. I hesitated however to regard - these two as distinct species, in consequence of the intermediate - characters presented by specimens from the Calumet, which are - regularly laminated like those of Burgess, and tubulous like those - of Grenville. It is possible that in the Burgess specimens, tubuli, - originally present, have been obliterated, and in organisms of this - grade, more or less altered by the processes of fossilisation, large - series of specimens should be compared before attempting to establish - specific distinctions." - - -(B.) Original Description of the Specimens added by Dr. Carpenter to -the above--in a Letter to Sir W. E. Logan. - -[_Journal of Geological Society_, February, 1865.] - - "The careful examination which I have made, in accordance with - the request you were good enough to convey to me from Dr. Dawson - and to second on your own part, with the structure of the very - extraordinary fossil which you have brought from the Laurentian - rocks of Canada,[Q] enables me most unhesitatingly to confirm the - sagacious determination of Dr. Dawson as to its Rhizopod characters - and Foraminiferal affinities, and at the same time furnishes new - evidence of no small value in support of that determination. In - this examination I have had the advantage of a series of sections - of the fossil much superior to those submitted to Dr. Dawson; and - also of a large series of decalcified specimens, of which Dr. Dawson - had only the opportunity of seeing a few examples after his memoir - had been written. These last are peculiarly instructive; since - in consequence of the complete infiltration of the chambers and - canals, originally occupied by the sarcode-body of the animal, by - mineral matter insoluble in dilute nitric acid, the removal of the - calcareous shell brings into view, not only the internal casts of - the chambers, but also casts of the interior of the 'canal system' - of the 'intermediate' or 'supplemental skeleton,' and even casts of - the interior of the very fine parallel tubuli which traverse the - proper walls of the chambers. And, as I have remarked elsewhere,[R] - 'such casts place before us far more exact representations of the - configuration of the animal body, and of the connections of its - different parts, than we could obtain even from living specimens by - dissolving away their shells with acid; its several portions being - disposed to heap themselves together in a mass when they lose the - support of the calcareous skeleton.' - -[Footnote Q: The specimens submitted to Dr. Carpenter were taken from a -block of Eozoon rock, obtained in the Petite Nation seigniory, too late -to afford Dr. Dawson an opportunity of examination. They are from the -same horizon as the Grenville specimens.--W. E. L.] - -[Footnote R: _Introduction to the Study of the Foraminifera_, p. 10.] - - "The additional opportunities I have thus enjoyed will be found, - I believe, to account satisfactorily for the differences to be - observed between Dr. Dawson's account of the Eozoon and my own. Had - I been obliged to form my conclusions respecting its structure only - from the specimens submitted to Dr. Dawson, I should very probably - have seen no reason for any but the most complete accordance with - his description: while if Dr. Dawson had enjoyed the advantage of - examining the entire series of preparations which have come under my - own observation, I feel confident that he would have anticipated the - corrections and additions which I now offer. - - "Although the general plan of growth described by Dr. Dawson, and - exhibited in his photographs of vertical sections of the fossil, - is undoubtedly that which is typical of Eozoon, yet I find that - the acervuline mode of growth, also mentioned by Dr. Dawson, very - frequently takes its place in the more superficial parts, where - the chambers, which are arranged in regular tiers in the laminated - portions, are heaped one upon another without any regularity, as is - particularly well shown in some decalcified specimens which I have - myself prepared from the slices last put into my hands. I see no - indication that this departure from the normal type of structure - has resulted from an injury; the transition from the regular to the - irregular mode of increase not being abrupt but gradual. Nor shall I - be disposed to regard it as a monstrosity; since there are many other - Foraminifera in which an originally definite plan of growth gives - place, in a later stage, to a like acervuline piling-up of chambers. - - "In regard to the form and relations of the chambers, I have little - to add to Dr. Dawson's description. The evidence afforded by their - internal casts concurs with that of sections, in showing that the - segments of the sarcode-body, by whose aggregation each layer was - constituted, were but very incompletely divided by shelly partitions; - this incomplete separation (as Dr. Dawson has pointed out) having - its parallel in that of the secondary chambers in Carpenteria. But I - have occasionally met with instances in which the separation of the - chambers has been as complete as it is in Foraminifera generally; and - the communication between them is then established by several narrow - passages exactly corresponding with those which I have described and - figured in Cycloclypeus.[S] - -[Footnote S: _Op. cit._, p. 294.] - - "The mode in which each successive layer originates from the one - which had preceded it, is a question to which my attention has been - a good deal directed; but I do not as yet feel confident that I - have been able to elucidate it completely. There is certainly no - regular system of apertures for the passage of stolons giving origin - to new segments, such as are found in all ordinary Polythalamous - Foraminifera, whether their type of growth be rectilinear, spiral, - or cyclical; and I am disposed to believe that where one layer is - separated from another by nothing else than the proper walls of - the chambers,--which, as I shall presently show, are traversed by - multitudes of minute tubuli giving passage to pseudopodia,--the - coalescence of these pseudopodia on the external surface would - suffice to lay the foundation of a new layer of sarcodic segments. - But where an intermediate or supplemental skeleton, consisting of a - thick layer of solid calcareous shell, has been deposited between - two successive layers, it is obvious that the animal body contained - in the lower layer of chambers must be completely cut off from - that which occupies the upper, unless some special provision exist - for their mutual communication. Such a provision I believe to have - been made by the extension of bands of sarcode, through canals left - in the intermediate skeleton, from the lower to the upper tier of - chambers. For in such sections as happen to have traversed thick - deposits of the intermediate skeleton, there are generally found - passages distinguished from those of the ordinary canal-system by - their broad flat form, their great transverse diameter, and their - non-ramification. One of these passages I have distinctly traced - to a chamber, with the cavity of which it communicated through two - or three apertures in its proper wall; and I think it likely that - I should have been able to trace it at its other extremity into a - chamber of the superjacent tier, had not the plane of the section - passed out of its course. Riband-like casts of these passages are - often to be seen in decalcified specimens, traversing the void spaces - left by the removal of the thickest layers of the intermediate - skeleton. - - "But the organization of a new layer seems to have not unfrequently - taken place in a much more considerable extension of the sarcode-body - of the pre-formed layer; which either folded back its margin - over the surface already consolidated, in a manner somewhat like - that in which the mantle of a CyprÅ“a doubles back to deposit - the final surface-layer of its shell, or sent upwards wall-like - lamellæ, sometimes of very limited extent, but not unfrequently of - considerable length, which, after traversing the substance of the - shell, like trap-dykes in a bed of sandstone, spread themselves out - over its surface. Such, at least, are the only interpretations I can - put upon the appearances presented by decalcified specimens. For - on the one hand, it is frequently to be observed that two bands of - serpentine (or other infiltrated mineral), which represent two layers - of the original sarcode-body of the animal, approximate to each other - in some part of their course, and come into complete continuity; - so that the upper layer would seem at that part to have had its - origin in the lower. Again, even where these bands are most widely - separated, we find that they are commonly held together by vertical - lamellæ of the same material, sometimes forming mere tongues, but - often running to a considerable length. That these lamellæ have not - been formed by mineral infiltration into accidental fissures in the - shell, but represent corresponding extensions of the sarcode-body, - seems to me to be indicated not merely by the characters of their - surface, but also by the fact that portions of the canal-system may - be occasionally traced into connection with them. - - "Although Dr. Dawson has noticed that some parts of the sections - which he examined present the fine tubulation characteristic of - the shells of the Nummuline Foraminifera, he does not seem to have - recognised the fact, which the sections placed in my hands have - enabled me most satisfactorily to determine,--that the proper - walls of the chambers everywhere present the fine tubulation of - the Nummuline shell; a point of the highest importance in the - determination of the affinities of Eozoon. This tubulation, although - not seen with the clearness with which it is to be discerned in - recent examples of the Nummuline type, is here far better displayed - than it is in the majority of fossil Nummulites, in which the - tubuli have been filled up by the infiltration of calcareous - matter, rendering the shell-substance nearly homogeneous. In Eozoon - these tubuli have been filled up by the infiltration of a mineral - different from that of which the shell is composed, and therefore - not coalescing with it; and the tubular structure is consequently - much more satisfactorily distinguishable. In decalcified specimens, - the free margins of the casts of the chambers are often seen to be - bordered with a delicate white glistening fringe; and when this - fringe is examined with a sufficient magnifying power, it is seen to - be made up of a multitude of extremely delicate aciculi, standing - side by side like the fibres of asbestos. These, it is obvious, are - the internal casts of the fine tubuli which perforated the proper - wall of the chambers, passing directly from its inner to its outer - surface; and their presence in this situation affords the most - satisfactory confirmation of the evidence of that tubulation afforded - by thin sections of the shell-wall. - - "The successive layers, each having its own proper wall, are - often superposed one upon another without the intervention of any - supplemental or intermediate skeleton such as presents itself in - all the more massive forms of the Nummuline series; but a deposit - of this form of shell-substance, readily distinguishable by its - homogeneousness from the finely tubular shell immediately investing - the segments of the sarcode-body, is the source of the great - thickening which the calcareous zones often present in vertical - sections of Eozoon. The presence of this intermediate skeleton has - been correctly indicated by Dr. Dawson; but he does not seem to have - clearly differentiated it from the proper wall of the chambers. - All the tubuli which he has described belong to that canal system - which, as I have shown,[T] is limited in its distribution to the - intermediate skeleton, and is expressly designed to supply a channel - for its nutrition and augmentation. Of this canal system, which - presents most remarkable varieties in dimensions and distribution, we - learn more from the casts presented by decalcified specimens, than - from sections, which only exhibit such parts of it as their plane may - happen to traverse. Illustrations from both sources, giving a more - complete representation of it than Dr. Dawson's figures afford, have - been prepared from the additional specimens placed in my hands. - -[Footnote T: _Op. cit._, pp. 50, 51.] - - "It does not appear to me that the canal system takes its origin - directly from the cavity of the chambers. On the contrary, I believe - that, as in Calcarina (which Dr. Dawson has correctly referred to as - presenting the nearest parallel to it among recent Foraminifera), - they originate in lacunar spaces on the outside of the proper - walls of the chambers, into which the tubuli of those walls open - externally; and that the extensions of the sarcode-body which - occupied them were formed by the coalescence of the pseudopodia - issuing from those tubuli.[U] - -[Footnote U: _Op. cit._, p. 221.] - - "It seems to me worthy of special notice, that the canal system, - wherever displayed in transparent sections, is distinguished by a - yellowish brown coloration, so exactly resembling that which I have - observed in the canal system of recent Foraminifera (as Polystomella - and Calcarina) in which there were remains of the sarcode-body, that - I cannot but believe the infiltrating mineral to have been dyed by - the remains of sarcode still existing in the canals of Eozoon at the - time of its consolidation. If this be the case, the preservation - of this colour seems to indicate that no considerable metamorphic - action has been exerted upon the rock in which this fossil occurs. - And I should draw the same inference from the fact that the organic - structure of the shell is in many instances even more completely - preserved than it usually is in the Nummulites and other Foraminifera - of the Nummulitic limestone of the early Tertiaries. - - "To sum up,--That the _Eozoon_ finds its proper place in the - Foraminiferal series, I conceive to be conclusively proved by its - accordance with the great types of that series, in all the essential - characters of organization;--namely, the structure of the shell - forming the proper wall of the chambers, in which it agrees precisely - with Nummulina and its allies; the presence of an intermediate - skeleton and an elaborate canal system, the disposition of which - reminds us most of Calcarina; a mode of communication of the chambers - when they are most completely separated, which has its exact parallel - in Cycloclypeus; and an ordinary want of completeness of separation - between the chambers, corresponding with that which is characteristic - of Carpenteria. - - "There is no other group of the animal kingdom to which Eozoon - presents the slightest structural resemblance; and to the suggestion - that it may have been of kin to Nullipore, I can offer the most - distinct negative reply, having many years ago carefully studied the - structure of that stony Alga, with which that of Eozoon has nothing - whatever in common. - - "The objections which not unnaturally occur to those familiar with - only the ordinary forms of Foraminifera, as to the admission of - Eozoon into the series, do not appear to me of any force. These have - reference in the first place to the great _size_ of the organism; and - in the second, to its exceptional mode of growth. - - "1. It must be borne in mind that all the Foraminifera normally - increase by the continuous gemmation of new segments from those - previously formed; and that we have, in the existing types, the - greatest diversities in the extent to which this gemmation may - proceed. Thus in the Globigerinæ, whose shells cover to an unknown - thickness the sea bottom of all that portion of the Atlantic Ocean - which is traversed by the Gulf Stream, only eight or ten segments - are ordinarily produced by continuous gemmation; and if new segments - are developed from the last of these, they detach themselves so - as to lay the foundation of independent Globigerinæ. On the other - hand in Cycloclypeus, which is a discoidal structure attaining two - and a quarter inches in diameter, the number of segments formed by - continuous gemmation must be many thousand. Again, the Receptaculites - of the Canadian Silurian rocks, shown by Mr. Salter's drawings[V] - to be a gigantic Orbitolite, attains a diameter of twelve inches; - and if this were to increase by vertical as well as by horizontal - gemmation (after the manner of Tinoporus or Orbitoides) so that one - discoidal layer would be piled on another, it would form a mass - equalling Eozoon in its ordinary dimensions. To say, therefore, that - Eozoon cannot belong to the Foraminifera on account of its gigantic - size, is much as if a botanist who had only studied plants and - shrubs were to refuse to admit a tree into the same category. The - very same continuous gemmation which has produced an Eozoon would - produce an equal mass of independent Globigerinæ, if after eight - or ten repetitions of the process, the new segments were to detach - themselves. - -[Footnote V: _First Decade of Canadian Fossils_, pl. x.] - - "It is to be remembered, moreover, that the largest masses of sponges - are formed by continuous gemmation from an original Rhizopod segment; - and that there is no _à priori_ reason why a Foraminiferal organism - should not attain the same dimensions as a Poriferal one,--the - intimate relationship of the two groups, notwithstanding the - difference between their skeletons, being unquestionable. - - "2. The difficulty arising from the zoophytic plan of growth of - Eozoon is at once disposed of by the fact that we have in the recent - Polytrema (as I have shown, _op. cit._, p. 235) an organism nearly - allied in all essential points of structure to Rotalia, yet no - less aberrant in its plan of growth, having been ranked by Lamarck - among the Millepores. And it appears to me that Eozoon takes its - place quite as naturally in the Nummuline series as Polytrema in - the Rotaline. As we are led from the typical Rotalia, through the - less regular Planorbulina, to Tinoporus, in which the chambers are - piled up vertically, as well as multiplied horizontally, and thence - pass by an easy gradation to Polytrema, in which all regularity of - external form is lost; so may we pass from the typical Operculina or - Nummulina, through Heterostegina and Cycloclypeus to Orbitoides, in - which, as in Tinoporus, the chambers multiply both by horizontal and - by vertical gemmation; and from Orbitoides to Eozoon the transition - is scarcely more abrupt than from Tinoporus to Polytrema. - - "The general acceptance, by the most competent judges, of my views - respecting the primary value of the characters furnished by the - intimate structure of the shell, and the very subordinate value - of plan of growth, in the determination of the affinities of - Foraminifera, renders it unnecessary that I should dwell further on - my reasons for unhesitatingly affirming the Nummuline affinities of - Eozoon from the microscopic appearances presented by the proper wall - of its chambers, notwithstanding its very aberrant peculiarities; - and I cannot but feel it to be a feature of peculiar interest in - geological inquiry, that the true relations of by far the earliest - fossil yet known should be determinable by the comparison of a - portion which the smallest pin's head would cover, with organisms at - present existing." - - -(C.) Note on Specimens From Long Lake and Wentworth. - -[_Journal of Geological Society_, August, 1867.] - - "Specimens from Long Lake, in the collection of the Geological - Survey of Canada, exhibit white crystalline limestone with light - green compact or septariiform[W] serpentine, and much resemble some - of the serpentine limestones of Grenville. Under the microscope the - calcareous matter presents a delicate areolated appearance, without - lamination; but it is not an example of acervuline Eozoon, but rather - of fragments of such a structure, confusedly aggregated together, and - having the interstices and cell-cavities filled with serpentine. I - have not found in any of these fragments a canal system similar to - that of Eozoon Canadense, though there are casts of large stolons, - and, under a high power, the calcareous matter shows in many places - the peculiar granular or cellular appearance which is one of the - characters of the supplemental skeleton of that species. In a few - places a tubulated cell-wall is preserved, with structure similar to - that of Eozoon Canadense. - -[Footnote W: I use the term "septariiform" to denote the _curdled_ -appearance so often presented by the Laurentian serpentine.] - - "Specimens of Laurentian limestone from Wentworth, in the collection - of the Geological Survey, exhibit many rounded silicious bodies, some - of which are apparently grains of sand, or small pebbles; but others, - especially when freed from the calcareous matter by a dilute acid, - appear as rounded bodies, with rough surfaces, either separate or - aggregated in lines or groups, and having minute vermicular processes - projecting from their surfaces. At first sight these suggest the - idea of spicules; but I think it on the whole more likely that - they are casts of cavities and tubes belonging to some calcareous - Foraminiferal organism which has disappeared. Similar bodies, found - in the limestone of Bavaria, have been described by Gümbel, who - interprets them in the same way. They may also be compared with the - silicious bodies mentioned in a former paper as occurring in the - loganite filling the chambers of specimens of _Eozoon_ from Burgess." - - These specimens will be more fully referred to under Chapter VI. - - -(D.) Additional Structural Facts. - - I may mention here a peculiar and interesting structure which has - been detected in one of my specimens while these sheets were passing - through the press. It is an abnormal thickening of the calcareous - wall, extending across several layers, and perforated with large - parallel cylindrical canals, filled with dolomite, and running in - the direction of the laminæ; the intervening calcite being traversed - by a very fine and delicate canal system. It makes a nearer approach - to some of the Stromatoporæ mentioned in Chapter VI. than any other - Laurentian structure hitherto observed, and may be either an abnormal - growth of Eozoon, consequent on some injury, or a parasitic mass of - some Stromatoporoid organism overgrown by the laminæ of the fossil. - The structure of the dolomite in this specimen indicates that it - first lined the canals, and afterward filled them; an appearance - which I have also observed recently in the larger canals filled - with serpentine (Plate VIII., fig. 5). The cut below is an attempt, - only partially successful, to show the AmÅ“ba-like appearance, when - magnified, of the casts of the chambers of Eozoon, as seen on the - decalcified surface of a specimen broken parallel to the laminæ. - -[Illustration: Fig. 21_a_.] - -[Illustration: - Plate V. - -_Nature-print of Eozoon, showing laminated, acervuline, and fragmental - portions._ - -This is printed from an electrotype taken from an etched slab of -Eozoon, and not touched with a graver except to remedy some accidental -flaws in the plate. The diagonal white line marks the course of a -calcite vein.] - - - - -CHAPTER V. - -THE PRESERVATION OF EOZOON. - - -Perhaps nothing excites more scepticism as to this ancient fossil -than the prejudice existing among geologists that no organism can be -preserved in rocks so highly metamorphic as those of the Laurentian -series. I call this a prejudice, because any one who makes the -microscopic structure of rocks and fossils a special study, soon learns -that fossils undergo the most remarkable and complete chemical changes -without losing their minute structure, and that calcareous rocks if -once fossiliferous are hardly ever so much altered as to lose all -trace of the organisms which they contained, while it is a most common -occurrence to find highly crystalline rocks of this kind abounding in -fossils preserved as to their minute structure. - -Let us, however, look at the precise conditions under which this takes -place. - -When calcareous fossils of irregular surface and porous or cellular -texture, such as Eozoon was or corals were and are, become imbedded -in clay, marl, or other soft sediment, they can be washed out and -recovered in a condition similar to that of recent specimens, except -that their pores or cells if open may be filled with the material of -the matrix, or if not so open that they can be thus filled, they may be -more or less incrusted with mineral deposits introduced by water, or -may even be completely filled up in this way. But if such fossils are -contained in hard rocks, they usually fail, when these are broken, to -show their external surfaces, and, breaking across with the containing -rock, they exhibit their internal structure merely,--and this more -or less distinctly, according to the manner in which their cells or -cavities have been filled. Here the microscope becomes of essential -service, especially when the structures are minute. A fragment of -fossil wood which to the naked eye is nothing but a dark stone, or a -coral which is merely a piece of gray or coloured marble, or a specimen -of common crystalline limestone made up originally of coral fragments, -presents, when sliced and magnified, the most perfect and beautiful -structure. In such cases it will be found that ordinarily the original -substance of the fossil remains, in a more or less altered state. Wood -may be represented by dark lines of coaly matter, or coral by its -white or transparent calcareous laminæ; while the material which has -been introduced and which fills the cavities may so differ in colour, -transparency, or crystalline structure, as to act differently on -light, and so reveal the structure. These fillings are very curious. -Sometimes they are mere earthy or muddy matter. Sometimes they are -pure and transparent and crystalline. Often they are stained with -oxide of iron or coaly matter. They may consist of carbonate of lime, -silica or silicates, sulphate of baryta, oxides of iron, carbonate of -iron, iron pyrite, or sulphides of copper or lead, all of which are -common materials. They are sometimes so complicated that I have seen -even the minute cells of woody structures, each with several bands of -differently coloured materials deposited in succession, like the coats -of an onyx agate. - -A further stage of mineralization occurs when the substance of the -organism is altogether removed and replaced by foreign matter, either -little by little, or by being entirely dissolved or decomposed, -leaving a cavity to be filled by infiltration. In this state are some -silicified woods, and those corals which have been not filled with but -converted into silica, and can thus sometimes be obtained entire and -perfect by the solution in an acid of the containing limestone, or by -its removal in weathering. In this state are the beautiful silicified -corals obtained from the corniferous limestone of Lake Erie. It may be -well to present to the eye these different stages of fossilization. I -have attempted to do this in fig. 22, taking a tabulate coral of the -genus Favosites for an example, and supposing the materials employed to -be calcite and silica. Precisely the same illustration would apply to a -piece of wood, except that the cell-wall would be carbonaceous matter -instead of carbonate of lime. In this figure the dotted parts represent -carbonate of lime, the diagonally shaded parts silica or a silicate. -Thus we have, in the natural state, the walls of carbonate of lime -and the cavities empty. When fossilized the cavities may be merely -filled with carbonate of lime, or they may be filled with silica; or -the walls themselves may be replaced by silica and the cavities may -remain filled with carbonate of lime; or both the walls and cavities -may be represented by or filled with silica or silicates. The ordinary -specimens of Eozoon are in the third of these stages, though some exist -in the second, and I have reason to believe that some have reached to -the fifth. I have not met with any in the fourth stage, though this is -not uncommon in Silurian and Devonian fossils. - -[Illustration: Fig. 22. _Diagram showing different States of -Fossilization of a Cell of a Tabulate Coral._ - -(_a._) Natural condition--walls calcite, cell empty. (_b._) Walls -calcite, cell filled with the same. (_c._) Walls calcite, cell filled -with silica or silicate. (_d._) Walls silicified, cell filled with -calcite. (_e._) Walls silicified, cell filled with silica or silicate.] - -With regard to the calcareous organisms with which we have now to do, -when these are imbedded in pure limestone and filled with the same, so -that the whole rock, fossils and all, is identical in composition, and -when metamorphic action has caused the whole to become crystalline, -and perhaps removed the remains of carbonaceous matter, it may be very -difficult to detect any traces of fossils. But even in this case -careful management of light may reveal indications of structure, as in -some specimens of Eozoon described by the writer and Dr. Carpenter. In -many cases, however, even where the limestones have become perfectly -crystalline, and the cleavage planes cut freely across the fossils, -these exhibit their forms and minute structure in great perfection. -This is the case in many of the Lower Silurian limestones of Canada, -as I have elsewhere shown.[X] The gray crystalline Trenton limestone -of Montreal, used as a building stone, is an excellent illustration -of this. To the naked eye it is a gray marble composed of cleavable -crystals; but when examined in thin slices, it shows its organic -fragments in the greatest perfection, and all the minute structures -are perfectly marked out by delicate carbonaceous lines. The only -exception in this limestone is in the case of the Crinoids, in which -the cellular structure is filled with transparent calc-spar, perfectly -identical with the original solid matter, so that they appear solid -and homogeneous, and can be recognised only by their external forms. -The specimen represented in fig. 23, is a mass of Corals, Bryozoa, and -Crinoids, and shows these under a low power, as represented in the -figure; but to the naked eye it is merely a gray crystalline limestone. -The specimen represented in fig. 24 shows the Laurentian Eozoon in a -similar state of preservation. It is from a sketch by Dr. Carpenter, -and shows the delicate canals partly filled with calcite as clear and -colourless as that of the shell itself, and distinguishable only by -careful management of the light. - -[Footnote X: _Canadian Naturalist_, 1859; Microscopic Structure of -Canadian Limestones.] - -[Illustration: Fig. 23. _Slice of Crystalline Lower Silurian Limestone; -showing Crinoids, Bryozoa, and Corals in fragments._] - -[Illustration: Fig. 24. _Wall of Eozoon penetrated with Canals. The -unshaded portions filled with Calcite._ (_After Carpenter._)] - -In the case of recent and fossil Foraminifers, these--when not so -little mineralized that their chambers are empty, or only partially -filled, which is sometimes the case even with Eocene Nummulites -and Cretaceous forms of smaller size,--are very frequently filled -solid with calcareous matter, and as Dr. Carpenter well remarks, -even well preserved Tertiary Nummulites in this state often fail -greatly in showing their structures, though in the same condition -they occasionally show these in great perfection. Among the finest -I have seen are specimens from the Mount of Olives (fig. 19), and -Dr. Carpenter mentions as equally good those of the London clay of -Bracklesham. But in no condition do modern Foraminifera or those of -the Tertiary and Mesozoic rocks appear in greater perfection than when -filled with the hydrous silicate of iron and potash called glauconite, -and which gives by the abundance of its little bottle-green concretions -the name of "green-sand" to formations of this age both in Europe and -America. In some beds of green-sand every grain seems to have been -moulded into the interior of a microscopic shell, and has retained -its form after the frail envelope has been removed. In some cases the -glauconite has not only filled the chambers but has penetrated the -fine tubulation, and when the shell is removed, either naturally or -by the action of an acid, these project in minute needles or bundles -of threads from the surface of the cast. It is in the warmer seas, -and especially in the bed of the Ægean and of the Gulf Stream, that -such specimens are now most usually found. If we ask why this mineral -glauconite should be associated with Foraminiferal shells, the answer -is that they are both products of one kind of locality. The same sea -bottoms in which Foraminifera most abound are also those in which for -some unknown chemical reason glauconite is deposited. Hence no doubt -the association of this mineral with the great Foraminiferal formation -of the chalk. It is indeed by no means unlikely that the selection -by these creatures of the pure carbonate of lime from the sea-water -or its minute plants, may be the means of setting free the silica, -iron, and potash, in a state suitable for their combination. Similar -silicates are found associated with marine limestones, as far back as -the Silurian age; and Dr. Sterry Hunt, than whom no one can be a better -authority on chemical geology, has argued on chemical grounds that the -occurrence of serpentine with the remains of Eozoon is an association -of the same character. - -However this may be, the infiltration of the pores of Eozoon with -serpentine and other silicates has evidently been one main means of -the preservation of its structure. When so infiltrated no metamorphism -short of the complete fusion of the containing rock could obliterate -the minutest points of structure; and that such fusion has not -occurred, the preservation in the Laurentian rocks of the most delicate -lamination of the beds shows conclusively; while, as already stated, it -can be shown that the alteration which has occurred might have taken -place at a temperature far short of that necessary to fuse limestone. -Thus has it happened that these most ancient fossils have been -handed down to our time in a state of preservation comparable, as Dr. -Carpenter states, to that of the best preserved fossil Foraminifera -from the more recent formations that have come under his observation in -the course of all his long experience. - -Let us now look more minutely at the nature of the typical specimens -of Eozoon as originally observed and described, and then turn to those -preserved in other ways, or more or less destroyed and defaced. Taking -a polished specimen from Petite Nation, like that delineated in Plate -V., we find the shell represented by white limestone, and the chambers -by light green serpentine. By acting on the surface with a dilute -acid we etch out the calcareous part, leaving a cast in serpentine -of the cavities occupied by the soft parts; and when this is done in -polished slices these may be made to print their own characters on -paper, as has actually been done in the case of Plate V., which is an -electrotype taken from an actual specimen, and shows both the laminated -and acervuline parts of the fossil. If the process of decalcification -has been carefully executed, we find in the excavated spaces delicate -ramifying processes of opaque serpentine or transparent dolomite, which -were originally imbedded in the calcareous substance, and which are -often of extreme fineness and complexity. (Plate VI. and fig. 10.) -These are casts of the canals which traversed the shell when still -inhabited by the animal. In some well preserved specimens we find the -original cell-wall represented by a delicate white film, which under -the microscope shows minute needle-like parallel processes representing -its still finer tubuli. It is evident that to have filled these tubuli -the serpentine must have been introduced in a state of actual solution, -and must have carried with it no foreign impurities. Consequently we -find that in the chambers themselves the serpentine is pure; and if we -examine it under polarized light, we see that it presents a singularly -curdled or irregularly laminated appearance, which I have designated -under the name septariiform, as if it had an imperfectly crystalline -structure, and had been deposited in irregular laminæ, beginning at -the sides of the chambers, and filling them toward the middle, and -had afterward been cracked by shrinkage, and the cracks filled with a -second deposit of serpentine. Now, serpentine is a hydrous silicate of -magnesia, and all that we need to suppose is that in the deposits of -the Laurentian sea magnesia was present instead of iron and potash, -and we can understand that the Laurentian fossil has been petrified -by infiltration with serpentine, as more modern Foraminifera have -been with glauconite, which, though it usually has little magnesia, -often has a considerable percentage of alumina. Further, in specimens -of Eozoon from Burgess, the filling mineral is loganite, a compound -of silica, alumina, magnesia and iron, with water, and in certain -Silurian limestones from New Brunswick and Wales, in which the delicate -microscopic pores of the skeletons of stalked star-fishes or Crinoids -have been filled with mineral deposits, so that when decalcified -these are most beautifully represented by their casts, Dr. Hunt has -proved the filling mineral to be a silicate of alumina, iron, magnesia -and potash, intermediate between serpentine and glauconite. We have, -therefore, ample warrant for adhering to Dr. Hunt's conclusion that -the Laurentian serpentine was deposited under conditions similar to -those of the modern green-sand. Indeed, independently of Eozoon, it is -impossible that any geologist who has studied the manner in which this -mineral is associated with the Laurentian limestones could believe it -to have been formed in any other way. Nor need we be astonished at -the fineness of the infiltration by which these minute tubes, perhaps -1/10000 of an inch in diameter, are filled with mineral matter. The -micro-geologist well knows how, in more modern deposits, the finest -pores of fossils are filled, and that mineral matter in solution -can penetrate the smallest openings that the microscope can detect. -Wherever the fluids of the living body can penetrate, there also -mineral substances can be carried, and this natural injection, effected -under great pressure and with the advantage of ample time, can surpass -any of the feats of the anatomical manipulator. Fig. 25 represents -a microscopic joint of a Crinoid from the Upper Silurian of New -Brunswick, injected with the hydrous silicate already referred to, and -fig. 26 shows a microscopic chambered or spiral shell, from a Welsh -Silurian limestone, with its cavities filled with a similar substance. - -[Illustration: Fig. 25. _Joint of a Crinoid, having its pores injected -with a Hydrous Silicate._ - -Upper Silurian Limestone, Pole Hill, New Brunswick. Magnified 25 -diameters.] - -[Illustration: Fig. 26. _Shell from a Silurian Limestone, Wales; its -cavity filled with a Hydrous Silicate._ - -Magnified 25 diameters.] - -It is only necessary to refer to the attempts which have been made to -explain by merely mineral deposits the occurrence of the serpentine -in the canals and chambers of Eozoon, and its presenting the form it -does, to see that this is the case. Prof. Rowney, for example, to avoid -the force of the argument from the canal system, is constrained to -imagine that the whole mass has at one time been serpentine, and that -this has been partially washed away, and replaced by calcite. If so, -whence the deposition of the supposed mass of serpentine, which has to -be accounted for in this way as well as in the other? How did it happen -to be eroded into so regular chambers, leaving intermediate floors and -partitions. And, more wonderful still, how did the regular dendritic -bundles, so delicate that they are removed by a breath, remain perfect, -and endure until they were imbedded in calcareous spar? Further, how -does it happen that in some specimens serpentine and pyroxene seem to -have encroached upon the structure, as if they and not calcite were the -eroding minerals? How any one who has looked at the structures can for -a moment imagine such a possibility, it is difficult to understand. If -we could suppose the serpentine to have been originally deposited as -a cellular or laminated mass, and its cavities filled with calcite in -a gelatinous or semi-fluid state, we might suppose the fine processes -of serpentine to have grown outward into these cavities in the mass, -as fibres of oxide of iron or manganese have grown in the silica of -moss-agate; but this theory would be encompassed with nearly as great -mechanical and chemical difficulties. The only rational view that any -one can take of the process is, that the calcareous matter was the -original substance, and that it had delicate tubes traversing it which -became injected with serpentine. The same explanation, and no other, -will suffice for those delicate cell-walls, penetrated by innumerable -threads of serpentine, which must have been injected into pores. It is -true that there are in some of the specimens cracks filled with fibrous -serpentine or chrysotile, but these traverse the mass in irregular -directions, and they consist of closely packed angular prisms, -instead of a matrix of limestone penetrated by cylindrical threads of -serpentine. (Fig. 27.) Here I must once for all protest against the -tendency of some opponents of Eozoon to confound these structures and -the canal system of Eozoon with the acicular crystals, and dendritic -or coralloidal forms, observed in some minerals. It is easy to make -such comparisons appear plausible to the uninitiated, but practised -observers cannot be so deceived, the differences are too marked and -essential. In illustration of this, I may refer to the highly magnified -canals in figs. 28 and 29. Further, it is evident from the examination -of the specimens, that the chrysotile veins, penetrating as they often -do diagonally or transversely across both chambers and walls, must have -originated subsequently to the origin and hardening of the rock and its -fossils, and result from aqueous deposition of fibrous serpentine in -cracks which traverse alike the fossils and their matrix. In specimens -now before me, nothing can be more plain than this entire independence -of the shining silky veins of fibrous serpentine, and the fact of their -having been formed subsequently to the fossilization of the Eozoon; -since they can be seen to run across the lamination, and to branch off -irregularly in lines altogether distinct from the structure. This, -while it shows that these veins have no connection with the fossil, -shows also that the latter was an original ingredient of the beds when -deposited, and not a product of subsequent concretionary action. - -[Illustration: Fig. 27. _Diagram showing the different appearances -of the cell-wall of Eozoon and of a vein of Chrysotile, when highly -magnified._] - -[Illustration: Fig. 28. _Casts of Canals of Eozoon in Serpentine, -decalcified and highly magnified._] - -[Illustration: Fig. 29. _Canals of Eozoon._ - -Highly magnified.] - -Taking the specimens preserved by serpentine as typical, we now turn -to certain other and, in some respects, less characteristic specimens, -which are nevertheless very instructive. At the Calumet some of -the masses are partly filled with serpentine and partly with white -pyroxene, an anhydrous silicate of lime and magnesia. The two minerals -can readily be distinguished when viewed with polarized light; and in -some slices I have seen part of a chamber or group of canals filled -with serpentine and part with pyroxene. In this case the pyroxene -or the materials which now compose it, must have been introduced by -infiltration, as well as the serpentine. This is the more remarkable as -pyroxene is most usually found as an ingredient of igneous rocks; but -Dr. Hunt has shown that in the Laurentian limestones and also in veins -traversing them, it occurs under conditions which imply its deposition -from water, either cold or warm. Gümbel remarks on this:--"Hunt, in -a very ingenious manner, compares this formation and deposition of -serpentine, pyroxene, and loganite, with that of glauconite, whose -formation has gone on uninterruptedly from the Silurian to the Tertiary -period, and is even now taking place in the depths of the sea; it being -well known that Ehrenberg and others have already shown that many of -the grains of glauconite are casts of the interior of foraminiferal -shells. In the light of this comparison, the notion that the serpentine -and such like minerals of the primitive limestones have been formed, -in a similar manner, in the chambers of Eozoic Foraminifera, loses any -traces of improbability which it might at first seem to possess." - -In many parts of the skeleton of Eozoon, and even in the best -infiltrated serpentine specimens, there are portions of the cell-wall -and canal system which have been filled with calcareous spar or with -dolomite, so similar to the skeleton that it can be detected only under -the most favourable lights and with great care. (Fig. 24, _supra_.) -The same phenomena may be observed in joints of Crinoids from the -Palæozoic rocks, and they constitute proofs of organic origin even -more irrefragable than the filling with serpentine. Dr. Carpenter has -recently, in replying to the objections of Mr. Carter, made excellent -use of this feature of the preservation of Eozoon. It is further to -be remarked that in all the specimens of true Eozoon, as well as -in many other calcareous fossils preserved in ancient rocks, the -calcareous matter, even when its minute structures are not preserved -or are obscured, presents a minutely granular or curdled appearance, -arising no doubt from the original presence of organic matter, and not -recognised in purely inorganic calcite. - -Another style of these remarkable fossils is that of the Burgess -specimens. In these the walls have been changed into dolomite -or magnesian limestone, and the canals seem to have been wholly -obliterated, so that only the laminated structure remains. The material -filling the chambers is also an aluminous silicate named loganite; and -this seems to have been introduced, not so much in solution, as in -the state of muddy slime, since it contains foreign bodies, as grains -of sand and little groups of silicious concretions, some of which are -not unlikely casts of the interior of minute foraminiferal shells -contemporary with Eozoon, and will be noticed in the sequel. - -[Illustration: Fig. 30. _Eozoon from Tudor._ - -Two-thirds natural size. (_a._) Tubuli. (_b._) Canals. Magnified. _a_ -and _b_ from another specimen.] - -Still another mode of occurrence is presented by a remarkable specimen -from Tudor in Ontario, and from beds probably on the horizon of the -Upper Laurentian or Huronian.[Y] It occurs in a rock scarcely at all -metamorphic, and the fossil is represented by white carbonate of lime, -while the containing matrix is a dark-coloured coarse limestone. In -this specimen the material filling the chambers has not penetrated -the canals except in a few places, where they appear filled with dark -carbonaceous matter. In mode of preservation these Tudor specimens -much resemble the ordinary fossils of the Silurian rocks. One of -the specimens in the collection of the Geological Survey (fig. 30) -presents a clavate form, as if it had been a detached individual -supported on one end at the bottom of the sea. It shows, as does -also the original Calumet specimen, the septa approaching each other -and coalescing at the margin of the form, where there were probably -orifices communicating with the exterior. Other specimens of fragmental -Eozoon from the Petite Nation localities have their canals filled with -dolomite, which probably penetrated them after they were broken up -and imbedded in the rock. I have ascertained with respect to these -fragments of Eozoon, that they occur abundantly in certain layers of -the Laurentian limestone, beds of some thickness being in great part -made up of them, and coarse and fine fragments occur in alternate -layers, like the broken corals in some Silurian limestones. - -[Footnote Y: See Note B, Chap. III.] - -Finally, on this part of the subject, careful observation of many -specimens of Laurentian limestone which present no trace of Eozoon -when viewed by the naked eye, and no evidence of structure when acted -on with acids, are nevertheless organic, and consist of fragments -of Eozoon, and possibly of other organisms, not infiltrated with -silicates, but only with carbonate of lime, and consequently revealing -only obscure indications of their minute structure. I have satisfied -myself of this by long and patient investigations, which scarcely admit -of any adequate representation, either by words or figures. - -Every worker in those applications of the microscope to geological -specimens which have been termed micro-geology, is familiar with the -fact that crystalline forces and mechanical movements of material -often play the most fantastic tricks with fossilized organic matter. -In fossil woods, for example, we often have the tissues disorganized, -with radiating crystallizations of calcite and little spherical -concretions of quartz, or disseminated cubes and grains of pyrite, -or little veins filled with sulphate of barium or other minerals. We -need not, therefore, be surprised to find that in the venerable rocks -containing Eozoon, such things occur in the more highly crystalline -parts of the limestones, and even in some still showing traces of -the fossil. We find many disseminated crystals of magnetite, pyrite, -spinel, mica, and other minerals, curiously curved prisms of vermicular -mica, bundles of aciculi of tremolite and similar substances, veins of -calcite and crysolite or fibrous serpentine, which often traverse the -best specimens. Where these occur abundantly we usually find no organic -structures remaining, or if they exist they are in a very defective -state of preservation. Even in specimens presenting the lamination of -Eozoon to the naked eye, these crystalline actions have often destroyed -the minute structure; and I fear that some microscopists have been -victimised by having under their consideration only specimens in which -the actual characters had been too much defaced to be discernible. I -must here state that I have found some of the specimens sold under -the name of Eozoon Canadense by dealers in microscopical objects to -be almost or quite worthless, being destitute of any good structure, -and often merely pieces of Laurentian limestone with serpentine -grains only. I fear that the circulation of such specimens has done -much to cause scepticism as to the Foraminiferal nature of Eozoon. No -mistake can be greater than to suppose that any and every specimen -of Laurentian limestone must contain Eozoon. More especially have -I hitherto failed to detect traces of it in those carbonaceous or -graphitic limestones which are so very abundant in the Laurentian -country. Perhaps where vegetable matter was very abundant Eozoon -did not thrive, or on the other hand the growth of Eozoon may have -diminished the quantity of vegetable matter. It is also to be observed -that much compression and distortion have occurred in the beds of -Laurentian limestone and their contained fossils, and also that the -specimens are often broken by faults, some of which are so small as to -appear only on microscopic examination, and to shift the plates of the -fossil just as if they were beds of rock. This, though it sometimes -produces puzzling appearances, is an evidence that the fossils were -hard and brittle when this faulting took place, and is consequently -an additional proof of their extraneous origin. In some specimens it -would seem that the lower and older part of the fossil had been wholly -converted into serpentine or pyroxene, or had so nearly experienced -this change that only small parts of the calcareous wall can be -recognised. These portions correspond with fossil woods altogether -silicified, not only by the filling of the cells, but also by the -conversion of the walls into silica. I have specimens which manifestly -show the transition from the ordinary condition of filling with -serpentine to one in which the cell-walls are represented obscurely by -one shade of this mineral and the cavities by another. - -The above considerations as to mode of preservation of Eozoon concur -with those in previous chapters in showing its oceanic character; -but the ocean of the Eozoic period may not have been so deep as at -present, and its waters were probably warm and well stocked with -mineral matters derived from the newly formed land, or from hot springs -in its own bottom. On this point the interesting investigations of -Dr. Hunt with reference to the chemical conditions of the Silurian -seas, allow us to suppose that the Laurentian ocean may have been much -more richly stored, more especially with salts of lime and magnesia, -than that of subsequent times. Hence the conditions of warmth, light, -and nutriment, required by such gigantic Protozoans would all be -present, and hence, also no doubt, some of the peculiarities of its -mineralization. - - -NOTES TO CHAPTER V. - - -(A.) Dr. Sterry Hunt on the Mineralogy of Eozoon and the containing -Rocks. - - It was fortunate for the recognition of Eozoon that Dr. Hunt had, - before its discovery, made so thorough researches into the chemistry - of the Laurentian series, and was prepared to show the chemical - possibilities of the preservation of fossils in these ancient - deposits. The following able summary of his views was appended to the - original description of the fossil in the _Journal of the Geological - Society_. - - "The details of structure have been preserved by the introduction - of certain mineral silicates, which have not only filled up the - chambers, cells, and canals left vacant by the disappearance of the - animal matter, but have in very many cases been injected into the - tubuli, filling even their smallest ramifications. These silicates - have thus taken the place of the original sarcode, while the - calcareous septa remain. It will then be understood that when the - replacement of the Eozoon by silicates is spoken of, this is to be - understood of the soft parts only; since the calcareous skeleton is - preserved, in most cases, without any alteration. The vacant spaces - left by the decay of the sarcode may be supposed to have been filled - by a process of infiltration, in which the silicates were deposited - from solution in water, like the silica which fills up the pores of - wood in the process of silicification. The replacing silicates, so - far as yet observed, are a white pyroxene, a pale green serpentine, - and a dark green alumino-magnesian mineral, which is allied in - composition to chlorite and to pyrosclerite, and which I have - referred to loganite. The calcareous septa in the last case are found - to be dolomitic, but in the other instances are nearly pure carbonate - of lime. The relations of the carbonate and the silicates are well - seen in thin sections under the microscope, especially by polarized - light. The calcite, dolomite, and pyroxene exhibit their crystalline - structure to the unaided eye; and the serpentine and loganite are - also seen to be crystalline when examined with the microscope. When - portions of the fossil are submitted to the action of an acid, the - carbonate of lime is dissolved, and a coherent mass of serpentine is - obtained, which is a perfect cast of the soft parts of the Eozoon. - The form of the sarcode which filled the chambers and cells is - beautifully shown, as well as the connecting canals and the groups - of tubuli; these latter are seen in great perfection upon surfaces - from which the carbonate of lime has been partially dissolved. Their - preservation is generally most complete when the replacing mineral is - serpentine, although very perfect specimens are sometimes found in - pyroxene. The crystallization of the latter mineral appears, however, - in most cases to have disturbed the calcareous septa. - - "Serpentine and pyroxene are generally associated in these specimens, - as if their disposition had marked different stages of a continuous - process. At the Calumet, one specimen of the fossil exhibits the - whole of the sarcode replaced by serpentine; while, in another one - from the same locality, a layer of pale green translucent serpentine - occurs in immediate contact with the white pyroxene. The calcareous - septa in this specimen are very thin, and are transverse to the plane - of contact of the two minerals; yet they are seen to traverse both - the pyroxene and the serpentine without any interruption or change. - Some sections exhibit these two minerals filling adjacent cells, - or even portions of the same cell, a clear line of division being - visible between them. In the specimens from Grenville on the other - hand, it would seem as if the development of the Eozoon (considerable - masses of which were replaced by pyroxene) had been interrupted, and - that a second growth of the animal, which was replaced by serpentine, - had taken place upon the older masses, filling up their interstices." - - [Details of chemical composition are then given.] - - "When examined under the microscope, the loganite which replaces the - Eozoon of Burgess shows traces of cleavage-lines, which indicate a - crystalline structure. The grains of insoluble matter found in the - analysis, chiefly of quartz-sand, are distinctly seen as foreign - bodies imbedded in the mass, which is moreover marked by lines - apparently due to cracks formed by a shrinking of the silicate, and - subsequently filled by a further infiltration of the same material. - This arrangement resembles on a minute scale that of septaria. - Similar appearances are also observed in the serpentine which - replaces the Eozoon of Grenville, and also in a massive serpentine - from Burgess, resembling this, and enclosing fragments of the fossil. - In both of these specimens also grains of mechanical impurities are - detected by the microscope; they are however, rarer than in the - loganite of Burgess. - - "From the above facts it may be concluded that the various silicates - which now constitute pyroxene, serpentine, and loganite were directly - deposited in waters in the midst of which the Eozoon was still - growing, or had only recently perished; and that these silicates - penetrated, enclosed, and preserved the calcareous structure - precisely as carbonate of lime might have done. The association - of the silicates with the Eozoon is only accidental; and large - quantities of them, deposited at the same time, include no organic - remains. Thus, for example, there are found associated with the - Eozoon limestones of Grenville, massive layers and concretions of - pure serpentine; and a serpentine from Burgess has already been - mentioned as containing only small broken fragments of the fossil. - In like manner large masses of white pyroxene, often surrounded - by serpentine, both of which are destitute of traces of organic - structure, are found in the limestone at the Calumet. In some cases, - however, the crystallization of the pyroxene has given rise to - considerable cleavage-planes, and has thus obliterated the organic - structures from masses which, judging from portions visible here and - there, appear to have been at one time penetrated by the calcareous - plates of Eozoon. Small irregular veins of crystalline calcite, and - of serpentine, are found to traverse such pyroxene masses in the - Eozoon limestone of Grenville. - - "It appears that great beds of the Laurentian limestones are - composed of the ruins of the Eozoon. These rocks, which are white, - crystalline, and mingled with pale green serpentine, are similar in - aspect to many of the so-called primary limestones of other regions. - In most cases the limestones are non-magnesian, but one of them - from Grenville was found to be dolomitic. The accompanying strata - often present finely crystallized pyroxene, hornblende, phlogopite, - apatite, and other minerals. These observations bring the formation - of silicious minerals face to face with life, and show that their - generation was not incompatible with the contemporaneous existence - and the preservation of organic forms. They confirm, moreover, the - view which I some years since put forward, that these silicated - minerals have been formed, not by subsequent metamorphism in - deeply buried sediments, but by reactions going on at the earth's - surface.[Z] In support of this view, I have elsewhere referred to - the deposition of silicates of lime, magnesia, and iron from natural - waters, to the great beds of sepiolite in the unaltered Tertiary - strata of Europe; to the contemporaneous formation of neolite (an - aluimino-magnesian silicate related to loganite and chlorite in - composition); and to glauconite, which occurs not only in Secondary, - Tertiary, and Recent deposits, but also, as I have shown, in Lower - Silurian strata.[AA] This hydrous silicate of protoxide of iron - and potash, which sometimes includes a considerable proportion of - alumina in its composition, has been observed by Ehrenberg, Mantell, - and Bailey, associated with organic forms in a manner which seems - identical with that in which pyroxene, serpentine, and loganite - occur with the Eozoon in the Laurentian limestones. According to the - first of these observers, the grains of green-sand, or glauconite, - from the Tertiary limestone of Alabama, are casts of the interior - of Polythalamia, the glauconite having filled them by 'a species of - natural injection, which is often so perfect that not only the large - and coarse cells, but also the very finest canals of the cell-walls - and all their connecting tubes, are thus petrified and separately - exhibited.' Bailey confirmed these observations, and extended them. - He found in various Cretaceous and Tertiary limestones of the United - States, casts in glauconite, not only of _Foraminifera_, but of - spines of _Echinus_, and of the cavities of corals. Besides, there - were numerous red, green, and white casts of minute anastomosing - tubuli, which, according to Bailey, resemble the casts of the holes - made by burrowing sponges (_Cliona_) and worms. These forms are seen - after the dissolving of the carbonate of lime by a dilute acid. - He found, moreover, similar casts of _Foraminifera_, of minute - mollusks, and of branching tubuli, in mud obtained from soundings in - the Gulf Stream, and concluded that the deposition of glauconite is - still going on in the depths of the sea.[AB] Pourtales has followed - up these investigations on the recent formation of glauconite in - the Gulf Stream waters. He has observed its deposition also in - the cavities of _Millepores_, and in the canals in the shells - of _Balanus_. According to him, the glauconite grains formed in - _Foraminifera_ lose after a time their calcareous envelopes, and - finally become 'conglomerated into small black pebbles,' sections - of which still show under a microscope the characteristic spiral - arrangement of the cells.[AC] - -[Footnote Z: _Silliman's Journal_ [2], xxix., p. 284; xxxii., p. 286. -_Geology of Canada_, p. 577.] - -[Footnote AA: _Silliman's Journal_ [2], xxxiii., p. 277. _Geology of -Canada_, p. 487.] - -[Footnote AB: _Silliman's Journal_ [2], xxii., p. 280.] - -[Footnote AC: _Report of United States Coast-Survey_, 1858, p. 248.] - - "It appears probable from these observations that glauconite is - formed by chemical reactions in the ooze at the bottom of the sea, - where dissolved silica comes in contact with iron oxide rendered - soluble by organic matter; the resulting silicate deposits itself in - the cavities of shells and other vacant spaces. A process analogous - to this in its results, has filled the chambers and canals of the - Laurentian _Foraminifera_ with other silicates; from the comparative - rarity of mechanical impurities in these silicates, however, it would - appear that they were deposited in clear water. Alumina and oxide of - iron enter into the composition of loganite as well as of glauconite; - but in the other replacing minerals, pyroxene and serpentine, we - have only silicates of lime and magnesia, which were probably formed - by the direct action of alkaline silicates, either dissolved in - surface-waters, or in those of submarine springs, upon the calcareous - and magnesian salts of the sea-water." - - [As stated in the text, the canals of Eozoon are sometimes filled - with dolomite, or in part with serpentine and in part with dolomite.] - - -(B.) Silurian Limestones holding Fossils infiltrated with Hydrous -Silicate. - - Since my attention has been directed to this subject, many - illustrations have come under my notice of Silurian limestones in - which the pores of fossils are infiltrated with hydrous silicates - akin to glauconite and serpentine. A limestone of this kind, - collected by Mr. Robb, at Pole Hill, in New Brunswick, afforded not - only beautiful specimens of portions of Crinoids preserved in this - way, but a sufficient quantity of the material was collected for an - exact analysis, a note on which was published in the Proceedings of - the Royal Irish Academy, 1871. - - The limestone of Pole Hill is composed almost wholly of organic - fragments, cemented by crystalline carbonate of lime, and traversed - by slender veins of the same mineral. Among the fragments may be - recognised under the microscope portions of Trilobites, and of - brachiopod and gastropod shells, and numerous joints and plates - of Crinoids. The latter are remarkable for the manner in which - their reticulated structure, which is similar to that of modern - Crinoids, has been injected with a silicious substance, which is - seen distinctly in slices, and still more plainly in decalcified - specimens. This filling is precisely similar in appearance to the - serpentine filling the canals of Eozoon, the only apparent difference - being in the forms of the cells and tubes of the Crinoids, as - compared with those of the Laurentian fossil; the same silicious - substance also occupies the cavities of some of the small shells, - and occurs in mere amorphous pieces, apparently filling interstices. - From its mode of occurrence, I have not the slightest doubt that - it occupied the cavities of the crinoidal fragments while still - recent, and before they had been cemented together by the calcareous - paste. This silicious filling is therefore similar on the one hand - to that effected by the ancient serpentine of the Laurentian, and - on the other to that which results from the depositions of modern - glauconite. The analysis of Dr. Hunt, which I give below, fully - confirms these analogies. - - I may add that I have examined under the microscope portions of the - substance prepared by Dr. Hunt for analysis, and find it to retain - its form, showing that it is the actual filling of the cavities. I - have also examined the small amount of insoluble silica remaining - after his treatment with acid and alkaline solvents, and find it to - consist of angular and rounded grains of quartzose sand. - - The following are Dr. Hunt's notes:-- - - "The fossiliferous limestone from Pole Hill, New Brunswick, probably - of Upper Silurian age, is light gray and coarsely granular. When - treated with dilute hydrochloric acid, it leaves a residue of 5·9 per - cent., and the solution gives 1·8 per cent. of alumina and oxide of - iron, and magnesia equal to 1·35 of carbonate--the remainder being - carbonate of lime. The insoluble matter separated by dilute acid, - after washing by decantation from a small amount of fine flocculent - matter, consists, apart from an admixture of quartz grains, entirely - of casts and moulded forms of a peculiar silicate, which Dr. Dawson - has observed in decalcified specimens filling the pores of crinoidal - stems; and which when separated by an acid, resembles closely under - the microscope the coralloidal forms of arragonite known as _flos - ferri_, the surfaces being somewhat rugose and glistening with - crystalline faces. This silicate is sub-translucent, and of a pale - green colour, but immediately becomes of a light reddish brown when - heated to redness in the air, and gives off water when heated in a - tube, without however, changing its form. It is partially decomposed - by strong hydrochloric acid, yielding a considerable amount of - protosalt of iron. Strong hot sulphuric acid readily and completely - decomposes it, showing it to be a silicate of alumina and ferrous - oxide, with some magnesia and alkalies, but with no trace of lime. - The separated silica, which remains after the action of the acid, - is readily dissolved by a dilute solution of soda, leaving behind - nothing but angular and partially rounded grains of sand, chiefly - of colourless vitreous quartz. An analysis effected in the way just - described on 1·187 grammes gave the following results, which give, by - calculation, the centesimal composition of the mineral:-- - - Silica ·3290 38·93 = 20·77 oxygen· - Alumina ·2440 28·88 = 13·46 " - Protoxyd of iron ·1593 18·86} - Magnesia ·0360 4·25} = 6·29 " - Potash ·0140 1·69} - Soda ·0042 ·48} - Water ·0584 6·91 = 6·14 " - Insoluble, quartz ·3420 - ------ ------ - 1·1869 100·00 - - "A previous analysis of a portion of the mixture by fusion with - carbonate of soda gave, by calculation, 18·80 p. c. of protoxide of - iron, and amounts of alumina and combined silica closely agreeing - with those just given. - - "The oxygen ratios, as above calculated, are nearly as 3 : 2 : 1 : 1. - This mineral approaches in composition to the jollyte of Von Kobell, - from which it differs in containing a portion of alkalies, and only - one half as much water. In these respects it agrees nearly with the - silicate found by Robert Hoffman, at Raspenau, in Bohemia, where it - occurs in thin layers alternating with picrosmine, and surrounding - masses of Eozoon in the Laurentian limestones of that region;[AD] - the Eozoon itself being there injected with a hydrous silicate which - may be described as intermediate between glauconite and chlorite in - composition. The mineral first mentioned is compared by Hoffman to - fahlunite, to which jollyte is also related in physical characters as - well as in composition. Under the names of fahlunite, gigantolite, - pinite, etc., are included a great class of hydrous silicates, which - from their imperfectly crystalline condition, have generally been - regarded, like serpentine, as results of the alteration of other - silicates. It is, however, difficult to admit that the silicate - found in the condition described by Hoffman, and still more the - present mineral, which injects the pores of palæozoic Crinoids, can - be any other than an original deposition, allied in the mode of its - formation, to the serpentine, pyroxene, and other minerals which have - injected the Laurentian Eozoon, and the serpentine and glauconite, - which in a similar manner fill Tertiary and recent shells." - -[Footnote AD: _Journ. für Prakt. Chemie_, Bd. 106 (Erster Jahrgang, -1869), p. 356.] - - -(C.) Various Minerals filling Cavities of Fossils in the Laurentian. - - The following on this subject is from a memoir by Dr. Hunt in the - _Twenty-first Report of the Regents of the University of New York_, - 1874:-- - - "Recent investigations have shown that in some cases the - dissemination of certain of these minerals through the crystalline - limestones is connected with organic forms. The observations - of Dr. Dawson and myself on the Eozoon Canadense showed that - certain silicates, namely serpentine, pyroxene, and loganite, - had been deposited in the cells and chambers left vacant by the - disappearance of the animal matter from the calcareous skeleton of - the foraminiferous organism; so that when this calcareous portion is - removed by an acid there remains a coherent mass, which is a cast of - the soft parts of the animal, in which, not only the chambers and - connecting canals, but the minute tubuli and pores are represented - by solid mineral silicates. It was shown that this process must have - taken place immediately after the death of the animal, and must have - depended on the deposition of these silicates from the waters of the - ocean. - - "The train of investigation thus opened up, has been pursued by - Dr. Gümbel, Director of the Geological Survey of Bavaria, who, in - a recent remarkable memoir presented to the Royal Society of that - country, has detailed his results. - - "Having first detected a fossil identical with the Canadian Eozoon - (together with several other curious microscopic organic forms not - yet observed in Canada), replaced by serpentine in a crystalline - limestone from the primitive group of Bavaria, which he identified - with the Laurentian system of this country, he next discovered a - related organism, to which he has given the name of Eozoon Bavaricum. - This occurs in a crystalline limestone belonging to a series of rocks - more recent than the Laurentian, but older than the Primordial zone - of the Lower Silurian, and designated by him the Hercynian clay slate - series, which he conceives may represent the Cambrian system of Great - Britain, and perhaps correspond to the Huronian series of Canada and - the United States. The cast of the soft parts of this new fossil is, - according to Gümbel, in part of serpentine, and in part of hornblende. - - "His attention was next directed to the green hornblende (pargasite) - which occurs in the crystalline limestone of Pargas in Finland, and - remains when the carbonate of lime is dissolved as a coherent mass - closely resembling that left by the irregular and acervuline forms - of Eozoon. The calcite walls also sometimes show casts of tubuli.... - A white mineral, probably scapolite was found to constitute some - tubercles associated with the pargasite, and the two mineral species - were in some cases united in the same rounded grain. - - "Similar observations were made by him upon specimens of coccolite - or green pyroxene, occurring in rounded and wrinkled grains in a - Laurentian limestone from New York. These, according to Gümbel, - present the same connecting cylinders and branching stems as the - pargasite, and are by him supposed to have been moulded in the - same manner.... Very beautiful evidences of the same organic - structure consisting of the casts of tubuli and their ramifications, - were also observed by Gümbel in a purely crystalline limestone, - enclosing granules of chondrodite, hornblende, and garnet, from - Boden in Saxony. Other specimens of limestone, both with and without - serpentine and chondrodite, were examined without exhibiting any - traces of these peculiar forms; and these negative results are - justly deemed by Gümbel as going to prove that the structure of - the others is really, like that of Eozoon, the result of the - intervention of organic forms. Besides the minerals observed in the - replacing substance of Eozoon in Canada, viz., serpentine, pyroxene, - and loganite, Gümbel adds chondrodite, hornblende, scapolite, and - probably also pyrallolite, quartz, iolite, and dichroite." - - -(D.) Glauconites. - - The following is from a paper by Dr. Hunt in the _Report of the - Survey of Canada_ for 1866:-- - - "In connection with the Eozoon it is interesting to examine more - carefully into the nature of the matters which have been called - glauconite or green-sand. These names have been given to substances - of unlike composition, which, however, occur under similar - conditions, and appear to be chemical deposits from water, filling - cavities in minute fossils, or forming grains in sedimentary rocks - of various ages. Although greenish in colour, and soft and earthy - in texture, it will be seen that the various glauconites differ - widely in composition. The variety best known, and commonly regarded - as the type of the glauconites, is that found in the green-sand of - Cretaceous age in New Jersey, and in the Tertiary of Alabama; the - glauconite from the Lower Silurian rocks of the Upper Mississippi is - identical with it in composition. Analysis shows these glauconites to - be essentially hydrous silicates of protoxyd of iron, with more or - less alumina, and small but variable quantities of magnesia, besides - a notable amount of potash. This alkali is, however, sometimes - wanting, as appears from the analysis of a green-sand from Kent in - England, by that careful chemist, the late Dr. Edward Turner, and - in another examined by Berthier, from the _calcaire grossier_, near - Paris, which is essentially a serpentine in composition, being a - hydrous silicate of magnesia and protoxyd of iron. A comparison of - these last two will show that the loganite, which fills the ancient - Foraminifer of Burgess, is a silicate nearly related in composition. - - I. Green-sand from the _calcaire grossier_, near Paris. Berthier - (cited by Beudant, _Mineralogie_, ii., 178). - - II. Green-sand from Kent, England. Dr. Edward Turner (cited by - Rogers, Final Report, Geol. N. Jersey, page 206). - - III. Loganite from the Eozoon of Burgess. - - IV. Green-sand, Lower Silurian; Red Bird, Minnesota. - - V. Green-sand, Cretaceous, New Jersey. - - VI. Green-sand, Lower Silurian, Orleans Island. - - The last four analyses are by myself. - - I. II. III. IV. V. VI. - - Silica 40·0 48·5 35·14 46·58 50·70 50·7 - - Protoxyd of iron 24·7 22·0 8·60 20·61 22·50 8·6 - - Magnesia 16·6 3·8 31·47 1·27 2·16 3·7 - - Lime 3·3 .... .... 2·49 1·11 .... - - Alumina 1·7 17·0 10·15 11·45 8·03 19·8 - - Potash .... traces. .... 6·96 5·80 8·2 - - Soda .... .... .... ·98 ·75 ·5 - - Water 12·6 7·0 14·64 9·66 8·95 8·5 - ---- ---- ------ ------ ------ ----- - 98·9 98·3 100·00 100·00 100·00 100·0" - -[Illustration: - Plate VI. - - From a Photo. by Weston. Vincent Brooks, Day & Son Lith. - - CANAL SYSTEM OF EOZOON. - - SLICES OF THE FOSSIL (MAGNIFIED.) - - _To face Chap. 6._] - - - - -CHAPTER VI. - -CONTEMPORARIES AND SUCCESSORS OF EOZOON. - - -The name Eozoon, or Dawn-animal, raises the question whether we shall -ever know any earlier representative of animal life. Here I think -it necessary to explain that in suggesting the name Eozoon for the -earliest fossil, and Eozoic for the formation in which it is contained, -I had no intention to affirm that there may not have been precursors -of the Dawn-animal. By the similar term, Eocene, Lyell did not mean -to affirm that there may not have been modern types in the preceding -geological periods: and so the dawn of animal life may have had its -gray or rosy breaking at a time long anterior to that in which Eozoon -built its marble reefs. When the fossils of this early auroral time -shall be found, it will not be hard to invent appropriate names for -them. There are, however, two reasons that give propriety to the -name in the present state of our knowledge. One is, that the Lower -Laurentian rocks are absolutely the oldest that have yet come under -the notice of geologists, and at the present moment it seems extremely -improbable that any older sediments exist, at least in a condition to -be recognised as such. The other is that Eozoon, as a member of the -group Protozoa, of gigantic size and comprehensive type, and oceanic in -its habitat, is as likely as any other creature that can be imagined -to have been the first representative of animal life on our planet. -Vegetable life may have preceded it, nay probably did so by at least -one great creative æon, and may have accumulated previous stores of -organic matter; but if any older forms of animal life existed, it is -certain at least that they cannot have belonged to much simpler or more -comprehensive types. It is also to be observed that such forms of life, -if they did exist, may have been naked protozoa, which may have left no -sign of their existence except a minute trace of carbonaceous matter, -and perhaps not even this. - -But if we do not know, and perhaps we are not likely to know, any -animals older than Eozoon, may we not find traces of some of its -contemporaries, either in the Eozoon limestones themselves, or other -rocks associated with them? Here we must admit that a deep sea -Foraminiferal limestone may give a very imperfect indication of the -fauna of its time. A dredger who should have no other information as -to the existing population of the world, except what he could gather -from the deposits formed under several hundred fathoms of water, would -necessarily have very inadequate conceptions of the matter. In like -manner a geologist who should have no other information as to the -animal life of the Mesozoic ages than that furnished by some of the -thick beds of white chalk might imagine that he had reached a period -when the simplest kinds of protozoa predominated over all other -forms of life; but this impression would at once be corrected by the -examination of other deposits of the same age: so our inferences as to -the life of the Laurentian from the contents of its oceanic limestones -may be very imperfect, and it may yet yield other and various fossils. -Its possibilities are, however, limited by the fact that before we -reach this great depth in the earth's crust, we have already left -behind in much newer formations all traces of animal life except a -few of the lower forms of aquatic invertebrates; so that we are not -surprised to find only a limited number of living things, and those of -very low type. Do we then know in the Laurentian even a few distinct -species, or is our view limited altogether to Eozoon Canadense? In -answering this question we must bear in mind that the Laurentian itself -was of vast duration, and that important changes of life may have taken -place even between the deposition of the Eozoon limestones and that -of those rocks in which we find the comparatively rich fauna of the -Primordial age. This subject was discussed by the writer as early as -1865, and I may repeat here what could be said in relation to it at -that time:-- - -"In connection with these remarkable remains, it appeared desirable to -ascertain, if possible, what share these or other organic structures -may have had in the accumulation of the limestones of the Laurentian -series. Specimens were therefore selected by Sir W. E. Logan, and -slices were prepared under his direction. On microscopic examination, -a number of these were found to exhibit merely a granular aggregation -of crystals, occasionally with particles of graphite and other foreign -minerals, or a laminated mixture of calcareous and other matters, in -the manner of some more modern sedimentary limestones. Others, however, -were evidently made up almost entirely of fragments of Eozoon, or of -mixtures of these with other calcareous and carbonaceous fragments -which afford more or less evidence of organic origin. The contents of -these organic limestones may be considered under the following heads:-- - -1. Remains of Eozoon. - -2. Other calcareous bodies, probably organic. - -3. Objects imbedded in the serpentine. - -4. Carbonaceous matters. - -5. Perforations, or worm-burrows. - -"1. The more perfect specimens of Eozoon do not constitute the mass -of any of the larger specimens in the collection of the Survey; but -considerable portions of some of them are made up of material of -similar minute structure, destitute of lamination, and irregularly -arranged. Some of this material gives the impression that there may -have been organisms similar to Eozoon, but growing in an irregular -or acervuline manner without lamination. Of this, however, I cannot -be certain; and on the other hand there is distinct evidence of the -aggregation of fragments of Eozoon in some of these specimens. In -some they constitute the greater part of the mass. In others they -are embedded in calcareous matter of a different character, or in -serpentine or granular pyroxene. In most of the specimens the cells of -the fossils are more or less filled with these minerals; and in some -instances it would appear that the calcareous matter of fragments of -Eozoon has been in part replaced by serpentine." - -"2. Intermixed with the fragments of Eozoon above referred to, are -other calcareous matters apparently fragmentary. They are of various -angular and rounded forms, and present several kinds of structure. The -most frequent of these is a strong lamination varying in direction -according to the position of the fragments, but corresponding, as -far as can be ascertained, with the diagonal of the rhombohedral -cleavage. This structure, though crystalline, is highly characteristic -of crinoidal remains when preserved in altered limestones. The more -dense parts of Eozoon, destitute of tubuli, also sometimes show this -structure, though less distinctly. Other fragments are compact and -structureless, or show only a fine granular appearance; and these -sometimes include grains, patches, or fibres of graphite. In Silurian -limestones, fragments of corals and shells which have been partially -infiltrated with bituminous matter, show a structure like this. On -comparison with altered organic limestones of the Silurian system, -these appearances would indicate that in addition to the debris of -Eozoon, other calcareous structures, more like those of crinoids, -corals, and shells, have contributed to the formation of the -Laurentian limestones. - -"3. In the serpentine[AE] filling the chambers of a large specimen of -Eozoon from Burgess, there are numerous small pieces of foreign matter; -and the silicate itself is laminated, indicating its sedimentary -nature. Some of the included fragments appear to be carbonaceous, -others calcareous; but no distinct organic structure can be detected -in them. There are, however, in the serpentine, many minute silicious -grains of a bright green colour, resembling green-sand concretions; -and the manner in which these are occasionally arranged in lines and -groups, suggests the supposition that they may possibly be casts of -the interior of minute Foraminiferal shells. They may, however, be -concretionary in their origin. - -[Footnote AE: This is the dark green mineral named loganite by Dr. -Hunt.] - -"4. In some of the Laurentian limestones submitted to me by Sir W. -E. Logan, and in others which I collected some years ago at Madoc, -Canada West, there are fibres and granules of carbonaceous matter, -which do not conform to the crystalline structure, and present forms -quite similar to those which in more modern limestones result from -the decomposition of algæ. Though retaining mere traces of organic -structure, no doubt would be entertained as to their vegetable origin -if they were found in fossiliferous limestones. - -"5. A specimen of impure limestone from Madoc, in the collection of -the Canadian Geological Survey, which seems from its structure to -have been a finely laminated sediment, shows perforations of various -sizes, somewhat scalloped at the sides, and filled with grains of -rounded silicious sand. In my own collection there are specimens -of micaceous slate from the same region, with indications on their -weathered surfaces of similar rounded perforations, having the aspect -of Scolithus, or of worm-burrows. - -"Though the abundance and wide distribution of Eozoon, and the -important part it seems to have acted in the accumulation of limestone, -indicate that it was one of the most prevalent forms of animal -existence in the seas of the Laurentian period, the non-existence of -other organic beings is not implied. On the contrary, independently of -the indications afforded by the limestones themselves, it is evident -that in order to the existence and growth of these large Rhizopods, the -waters must have swarmed with more minute animal or vegetable organisms -on which they could subsist. On the other hand, though this is a less -certain inference, the dense calcareous skeleton of Eozoon may indicate -that it also was liable to the attacks of animal enemies. It is also -possible that the growth of Eozoon, or the deposition of the serpentine -and pyroxene in which its remains have been preserved, or both, may -have been connected with certain oceanic depths and conditions, and -that we have as yet revealed to us the life of only certain stations -in the Laurentian seas. Whatever conjectures we may form on these more -problematic points, the observations above detailed appear to establish -the following conclusions:-- - -"First, that in the Laurentian period, as in subsequent geological -epochs, the Rhizopods were important agents in the accumulation of -beds of limestone; and secondly, that in this early period these low -forms of animal life attained to a development, in point of magnitude -and complexity, unexampled, in so far as yet known, in the succeeding -ages of the earth's history. This early culmination of the Rhizopods is -in accordance with one of the great laws of the succession of living -beings, ascertained from the study of the introduction and progress of -other groups; and, should it prove that these great Protozoans were -really the dominant type of animals in the Laurentian period, this fact -might be regarded as an indication that in these ancient rocks we may -actually have the records of the first appearance of animal life on our -planet." - -With reference to the first of the above heads, I have now to state -that it seems quite certain that the upper and younger portions of -the masses of Eozoon often passed into the acervuline form, and the -period in which this change took place seems to have depended on -circumstances. In some specimens there are only a few regular layers, -and then a heap of irregular cells. In other cases a hundred or more -regular layers were formed; but even in this case little groups of -irregular cells occurred at certain points near the surface. This -may be seen in plate III. I have also found some masses clearly not -fragmental which consist altogether of acervuline cells. A specimen -of this kind is represented in fig. 31. It is oval in outline, about -three inches in length, wholly made up of rounded or cylindrical -cells, the walls of which have a beautiful tubular structure, but -there is little or no supplemental skeleton. Whether this is a portion -accidentally broken off from the top of a mass of Eozoon, or a -peculiar varietal form, or a distinct species, it would be difficult -to determine. In the meantime I have described it as a variety, -"_acervulina_," of the species Eozoon Canadense.[AF] Another variety -also, from Petite Nation, shows extremely thin laminæ, closely placed -together and very massive, and with little supplemental skeleton. This -may be allied to the last, and may be named variety "_minor_." - -[Footnote AF: _Proceedings of Geological Society_, 1875.] - -[Illustration: Fig. 31. _Acervuline Variety of Eozoon, St. Pierre._ - -(_a._) General form, half natural size. (_b._) Portion of cellular -interior, magnified, showing the course of the tubuli.] - -All this, however, has nothing to do with the layers of fragments of -Eozoon which are scattered through the Laurentian limestones. In these -the fossil is sometimes preserved in the ordinary manner, with its -cavities filled with serpentine, and the thicker parts of the skeleton -having their canals filled with this substance. In this case the -chambers may have been occupied with serpentine before it was broken -up. At St. Pierre there are distinct layers of this kind, from half an -inch to several inches in thickness, regularly interstratified with -the ordinary limestone. In other layers no serpentine occurs, but the -interstices of the fragments are filled with crystalline dolomite or -magnesian limestone, which has also penetrated the canals; and there -are indications, though less manifest, that some at least of the layers -of pure limestone are composed of fragmental Eozoon. In the Laurentian -limestone of Wentworth, belonging apparently to the same band with -that of St. Pierre, there are many small rounded pieces of limestone, -evidently the debris of some older rock, broken up and rounded by -attrition. In some of these fragments the structure of Eozoon may be -plainly perceived. This shows that still older limestones composed of -Eozoon were at that time undergoing waste, and carries our view of the -existence of this fossil back to the very beginning of the Laurentian. - -With respect to organic fragments not showing the structure of Eozoon, -I have not as yet been able to refer these to any definite origin. Some -of them may be simply thick portions of the shell of Eozoon with their -pores filled with calcite, so as to present a homogeneous appearance. -Others have much the appearance of fragments of such Primordial forms -as _Archæocyathus_, to be described in the sequel; but after much -careful search, I have thus far been unable to say more than I could -say in 1865. - -[Illustration: Fig. 32. _Archæospherinæ from St. Pierre._ - -(_a._) Specimens dissolved out by acid. The lower one showing interior -septa. (_b._) Specimens seen in section.] - -[Illustration: Fig. 33. _Archæospherinæ from Burgess Eozoon._ - -Magnified.] - -[Illustration: Fig. 34. _Archæospherinæ from Wentworth Limestone._ - -Magnified.] - -It is different, however, with the round cells infiltrated with -serpentine and with the silicious grains included in the loganite. I -have already referred to and figured (fig. 18) the remarkable rounded -bodies occurring at Long Lake. I now figure similar bodies found mixed -with fragmental Eozoon and in separate thin layers at St. Pierre (fig. -32), also some of the singular grains found in the loganite occupying -the chambers of Eozoon from Burgess (fig. 33), and a beaded body set -free by acid, with others of irregular forms, from the limestone of -Wentworth (fig. 34). All these I think are essentially of the same -nature, namely, chambers originally invested with a tubulated wall -like Eozoon, and aggregated in groups, sometimes in a linear manner, -sometimes spirally, like those Globigerinæ which constitute the mass -of modern deep-sea dredgings and also of the chalk. These bodies occur -dispersed in the limestone, arranged in thin layers parallel to the -bedding or sometimes in the large chamber-cavities of Eozoon. They -are so variable in size and form that it is not unlikely they may be -of different origins. The most probable of these may be thus stated. -First, they may in some cases be the looser superficial parts of the -surface of Eozoon broken up into little groups of cells. Secondly, -they may be few-celled germs or buds given off from Eozoon. Thirdly, -they may be smaller Foraminifera, structurally allied to Eozoon, but -in habit of growth resembling those little globe-shaped forms which, -as already stated, abound in chalk and in the modern ocean. The latter -view I should regard as highly probable in the case of many of them; -and I have proposed for them, in consequence, and as a convenient name, -_Archæospherinæ_, or ancient spherical animals. - -Carbonaceous matter is rare in the true Eozoon limestones, and, as -already stated, I would refer the Laurentian graphite or plumbago -mainly to plants. With regard to the worm-burrows referred to in 1865, -there can be no doubt of their nature, but there is some doubt as to -whether the beds that contain them are really Lower Laurentian. They -may be Upper Laurentian or Huronian. I give here figures of these -burrows as published in 1866[AG] (fig. 35). The rocks which contain -them hold also fragments of Eozoon, and are not known to contain other -fossils. - -[Footnote AG: _Journal of Geological Society._] - -[Illustration: Fig. 35. _Annelid Burrows, Laurentian or Huronian._ - -Fig 1. _Transverse section of Worm-burrow_--magnified, as a transparent -object. (_a._) Calcareo-silicious rock. (_b._) Space filled with -calcareous spar. (_c._) Sand agglutinated and stained black. (_d._) -Sand less agglutinated and uncoloured. Fig. 2. _Transverse section of -Worm-burrow on weathered surface_, natural size. Fig. 3. _The same_, -magnified.] - -If we now turn to other countries in search of contemporaries of -Eozoon, I may refer first to some specimens found by my friend Dr. -Honeyman at Arisaig, in Nova Scotia, in beds underlying the Silurian -rocks of that locality, but otherwise of uncertain age. I do not vouch -for them as Laurentian, and if of that age they seem to indicate a -species distinct from that of Canada proper. They differ in coarser -tubulation, and in their canals being large and beaded, and less -divergent. I proposed for these specimens, in some notes contributed to -the survey of Canada, the name _Eozoon Acadianum_. - -Dr. Gümbel, the Director of the Geological Survey of Bavaria, is -one of the most active and widely informed of European geologists, -combining European knowledge with an extensive acquaintance with the -larger and in some respects more typical areas of the older rocks in -America, and stratigraphical geology with enthusiastic interest in the -microscopic structures of fossils. He at once and in a most able manner -took up the question of the application of the discoveries in Canada -to the rocks of Bavaria. The spirit in which he did so may be inferred -from the following extract:-- - -"The discovery of organic remains in the crystalline limestones of the -ancient gneiss of Canada, for which we are indebted to the researches -of Sir William Logan and his colleagues, and to the careful microscopic -investigations of Drs. Dawson and Carpenter, must be regarded as -opening a new era in geological science. - -"This discovery overturns at once the notions hitherto commonly -entertained with regard to the origin of the stratified primary -limestones, and their accompanying gneissic and quartzose strata, -included under the general name of primitive crystalline schists. It -shows us that these crystalline stratified rocks, of the so-called -primary system, are only a backward prolongation of the chain of -fossiliferous strata; the elements of which were deposited as oceanic -sediment, like the clay-slates, limestones, and sandstones of the -palæozoic formations, and under similar conditions, though at a time -far more remote, and more favourable to the generation of crystalline -mineral compounds. - -"In this discovery of organic remains in the primary rocks, we hail -with joy the dawn of a new epoch in the critical history of these -earlier formations. Already in its light, the primeval geological time -is seen to be everywhere animated, and peopled with new animal forms -of whose very existence we had previously no suspicion. Life, which -had hitherto been supposed to have first appeared in the Primordial -division of the Silurian period, is now seen to be immeasurably -lengthened beyond its former limit, and to embrace in its domain the -most ancient known portions of the earth's crust. It would almost -seem as if organic life had been awakened simultaneously with the -solidification of the earth's crust. - -"The great importance of this discovery cannot be clearly understood, -unless we first consider the various and conflicting opinions -and theories which had hitherto been maintained concerning the -origin of these primary rocks. Thus some, who consider them as the -first-formed crust of a previously molten globe, regard their apparent -stratification as a kind of concentric parallel structure, developed -in the progressive cooling of the mass from without. Others, while -admitting a similar origin of these rocks, suppose their division -into parallel layers to be due, like the lamination of clay-slates, -to lateral pressure. If we admit such views, the igneous origin of -schistose rocks becomes conceivable, and is in fact maintained by many. - -"On the other hand, we have the school which, while recognising the -sedimentary origin of these crystalline schists, supposes them to -have been metamorphosed at a later period; either by the internal -heat, acting in the deeply buried strata; by the proximity of eruptive -rocks; or finally, through the agency of permeating waters charged with -certain mineral salts. - -"A few geologists only have hitherto inclined to the opinion that -these crystalline schists, while possessing real stratification, -and sedimentary in their origin, were formed at a period when the -conditions were more favourable to the production of crystalline -materials than at present. According to this view, the crystalline -structure of these rocks is an original condition, and not one -superinduced at a later period by metamorphosis. In order, however, -to arrange and classify these ancient crystalline rocks, it becomes -necessary to establish by superposition, or by other evidence, -differences in age, such as are recognised in the more recent -stratified deposits. The discovery of similar organic remains, -occupying a determinate position in the stratification, in different -and remote portions of these primitive rocks, furnishes a powerful -argument in favour of the latter view, as opposed to the notion which -maintains the metamorphic origin of the various minerals and rocks of -these ancient formations; so that we may regard the direct formation of -these mineral elements, at least so far as these fossiliferous primary -limestones are concerned, as an established fact." - -His first discovery is thus recorded, in terms which show the very -close resemblance of the Bavarian and Canadian Eozoic. - -"My discovery of similar organic remains in the serpentine-limestone -from near Passau was made in 1865, when I had returned from my -geological labours of the summer, and received the recently published -descriptions of Messrs. Logan, Dawson, etc. Small portions of this -rock, gathered in the progress of the Geological Survey in 1854, -and ever since preserved in my collection, having been submitted -to microscopic examination, confirmed in the most brilliant manner -the acute judgment of the Canadian geologists, and furnished -palæontological evidence that, notwithstanding the great distance which -separates Canada from Bavaria, the equivalent primitive rocks of the -two regions are characterized by similar organic remains; showing at -the same time that the law governing the definite succession of organic -life on the earth is maintained even in these most ancient formations. -The fragments of serpentine-limestone, or ophicalcite, in which I first -detected the existence of Eozoon, were like those described in Canada, -in which the lamellar structure is wanting, and offer only what Dr. -Carpenter has called an acervuline structure. For further confirmation -of my observations, I deemed it advisable, through the kindness of -Sir Charles Lyell, to submit specimens of the Bavarian rock to the -examination of that eminent authority, Dr. Carpenter, who, without any -hesitation, declared them to contain Eozoon. - -"This fact being established, I procured from the quarries near Passau -as many specimens of the limestone as the advanced season of the year -would permit; and, aided by my diligent and skillful assistants, -Messrs. Reber and Schwager, examined them by the methods indicated by -Messrs. Dawson and Carpenter. In this way I soon convinced myself of -the general similarity of our organic remains with those of Canada. -Our examinations were made on polished sections and in portions etched -with dilute nitric acid, or, better, with warm acetic acid. The most -beautiful results were however obtained by etching moderately thin -sections, so that the specimens may be examined at will either by -reflected or transmitted light. - -"The specimens in which I first detected Eozoon came from a quarry -at Steinhag, near Obernzell, on the Danube, not far from Passau. The -crystalline limestone here forms a mass from fifty to seventy feet -thick, divided into several beds, included in the gneiss, whose general -strike in this region is N.W., with a dip of 40°-60° N.E. The limestone -strata of Steinhag have a dip of 45° N.E. The gneiss of this vicinity -is chiefly grey, and very silicious, containing dichroite, and of -the variety known as dichroite-gneiss; and I conceive it to belong, -like the gneiss of Bodenmais and Arber, to that younger division of -the primitive gneiss system which I have designated as the Hercynian -gneiss formation; which, both to the north, between Tischenreuth and -Mahring, and to the south on the north-west of the mountains of Ossa, -is immediately overlaid by the mica-slate formation. Lithologically, -this newer division of the gneiss is characterized by the predominance -of a grey variety, rich in quartz, with black magnesian-mica and -orthoclase, besides which a small quantity of oligoclase is never -wanting. A further characteristic of this Hercynian gneiss is the -frequent intercalation of beds of rocks rich in hornblende, such as -hornblende-schist, amphibolite, diorite, syenite, and syenitic granite, -and also of serpentine and granulite. Beds of granular limestone, -or of calcareous schists are also never altogether wanting; while -iron pyrites and graphite, in lenticular masses, or in local beds -conformable to the great mass of the gneiss strata, are very generally -present. - -"In the large quarry of Steinhag, from which I first obtained the -Eozoon, the enclosing rock is a grey hornblendic gneiss, which -sometimes passes into a hornblende-slate. The limestone is in many -places overlaid by a bed of hornblende-schist, sometimes five feet -in thickness, which separates it from the normal gneiss. In many -localities, a bed of serpentine, three or four feet thick, is -interposed between the limestone and the hornblende-schist; and in -some cases a zone, consisting chiefly of scapolite, crystalline and -almost compact, with an admixture however of hornblende and chlorite. -Below the serpentine band, the crystalline limestone appears divided -into distinct beds, and encloses various accidental minerals, among -which are reddish-white mica, chlorite, hornblende, tremolite, -chondrodite, rosellan, garnet, and scapolite, arranged in bands. -In several places the lime is mingled with serpentine, grains or -portions of which, often of the size of peas, are scattered through -the limestone with apparent irregularity, giving rise to a beautiful -variety of ophicalcite or serpentine-marble. These portions, which are -enclosed in the limestone destitute of serpentine, always present a -rounded outline. In one instance there appears, in a high naked wall -of limestone without serpentine, the outline of a mass of ophicalcite, -about sixteen feet long and twenty-five feet high, which, rising from -a broad base, ends in a point, and is separated from the enclosing -limestone by an undulating but clearly defined margin, as already well -described by Wineberger. This mass of ophicalcite recalls vividly a -reef-like structure. Within this and similar masses of ophicalcite in -the crystalline limestone, there are, so far as my observations in 1854 -extend, no continuous lines or concentric layers of serpentine to be -observed, this mineral being always distributed in small grains and -patches. The few apparently regular layers which may be observed are -soon interrupted, and the whole aggregation is irregular." - -It will be observed that this acervuline Eozoon of Steinhag appears to -exist in large reefs, and that in its want of lamination it differs -from the Canadian examples. In fossils of low organization, like -Foraminifera, such differences are often accidental and compatible with -specific unity, but yet there may be a difference specifically in the -Bavarian Eozoon as compared with the Canadian. - -Gümbel also found in the Finnish and Bavarian limestones knotted -chambers, like those of Wentworth above mentioned (fig. 36), which he -regards as belonging to some other organism than Eozoon; and flocculi -having tubes, pores, and reticulations which would seem to point to the -presence of structures akin to sponges or possibly remains of seaweeds. -These observations Gümbel has extended into other localities in Bavaria -and Bohemia, and also in Silesia and Sweden, establishing the existence -of Eozoon fossils in all the Laurentian limestones of the middle and -north of Europe. - -[Illustration: Fig. 36. _Archæospherinæ from Pargas in Finland._ -(_After Gümbel._) - -Magnified.] - -Gümbel has further found in beds overlying the older Eozoic series, -and probably of the same age with the Canadian Huronian, a different -species of Eozoon, with smaller and more contracted chambers, and -still finer and more crowded canals. This, which is to be regarded as -a distinct species, or at least a well-marked varietal form, he has -named _Eozoon Bavaricum_ (fig. 37). Thus this early introduction of -life is not peculiar to that old continent which we sometimes call the -New World, but applies to Europe as well, and Europe has furnished a -successor to Eozoon in the later Eozoic or Huronian period. In rocks of -this age in America, after long search and much slicing of limestones, -I have hitherto failed to find any decided organic remains other than -the Tudor and Madoc specimens of Eozoon. If these are really Huronian -and not Laurentian, the Eozoon from this horizon does not sensibly -differ from that of the Lower Laurentian. The curious limpet-like -objects from Newfoundland, discovered by Murray, and described by -Billings,[AH] under the name _Aspidella_, are believed to be Huronian, -but they have no connection with Eozoon, and therefore need not detain -us here. - -[Footnote AH: _Canadian Naturalist_, 1871.] - -[Illustration: Fig. 37. _Section of Eozoon Bavaricum, with Serpentine, -from the Crystalline Limestone of the Hercynian primitive Clay-state -Formation at Hohenberg; 25 diameters._ - -(_a._) Sparry carbonate of lime. (_b._) Cellular carbonate of lime. -(_c._) System of tubuli. (_d._) Serpentine replacing the coarser -ordinary variety. (_e._) Serpentine and hornblende replacing the finer -variety, in the very much contorted portions.] - -Leaving the Eozoic age, we find ourselves next in the Primordial or -Cambrian, and here we discover the sea already tenanted by many -kinds of crustaceans and shell-fishes, which have been collected and -described by palæontologists in Bohemia, Scandinavia, Wales, and North -America;[AI] curiously enough, however, the rocks of this age are -not so rich in Foraminifera as those of some succeeding periods. Had -this primitive type played out its part in the Eozoic and exhausted -its energies, and did it remain in abeyance in the Primordial age to -resume its activity in the succeeding times? It is not necessary to -believe this. The geologist is familiar with the fact, that in one -formation he may have before him chiefly oceanic and deep-sea deposits, -and in another those of the shallower waters, and that alternations -of these may, in the same age or immediately succeeding ages, present -very different groups of fossils. Now the rocks and fossils of the -Laurentian seem to be oceanic in character, while the Huronian and -early Primordial rocks evidence great disturbances, and much coarse -and muddy sediment, such as that found in shallows or near the land. -They abound in coarse conglomerates, sandstones and thick beds of slate -or shale, but are not rich in limestones, which do not in the parts -of the world yet explored regain their importance till the succeeding -Siluro-Cambrian age. No doubt there were, in the Primordial, deep-sea -areas swarming with Foraminifera, the successors of Eozoon; but these -are as yet unknown or little known, and our known Primordial fauna is -chiefly that of the shallows. Enlarged knowledge may thus bridge over -much of the apparent gap in the life of these two great periods. - -[Footnote AI: Barrande, Angelin, Hicks, Hall, Billings, etc.] - -Only as yet on the coast of Labrador and neighbouring parts of North -America, and in rocks that were formed in seas that washed the old -Laurentian rocks, in which Eozoon was already as fully sealed up as -it is at this moment, do we find Protozoa which can claim any near -kinship to the proto-foraminifer. These are the fossils of the genus -_Archæocyathus_--"ancient cup-sponges, or cup-foraminifers," which -have been described in much detail by Mr. Billings in the reports of -the Canadian Survey. Mr. Billings regards them as possibly sponges, -or as intermediate between these and Foraminifera, and the silicious -spicules found in some of them justify this view, unless indeed, as -partly suspected by Mr. Billings, these belong to true sponges which -may have grown along with Archæocyathus or attached to it. Certain -it is, however, that if allied to sponges, they are allied also to -Foraminifera, and that some of them deviate altogether from the sponge -type and become calcareous chambered bodies, the animals of which can -have differed very little from those of the Laurentian Eozoon. It is -to these calcareous Foraminiferal species that I shall at present -restrict my attention. I give a few figures, for which I am indebted to -Mr. Billings, of three of his species (figs. 38 to 40), with enlarged -drawings of the structures of one of them which has the most decidedly -foraminiferal characters. - -[Illustration: Fig. 38. _Archæocyathus Minganensis--a Primordial -Protozoon._ (_After Billings._) - -(_a._) Pores of the inner wall.] - -[Illustration: Fig. 39. _Archæocyathus profundus--showing the base of -attachment and radiating chambers._ (_After Billings._)] - -[Illustration: Fig. 40. _Archæocyathus Atlanticus--showing outer -surface and longitudinal and transverse sections._ (_After Billings._)] - -[Illustration: Fig. 41. _Structures of Archæocyathus Profundus._ - -(_a._) Lower acervuline portion. (_b._) Upper portion, with three of -the radiating laminæ. (_c._) Portion of lamina with pores and thickened -part with canals. In figs. _a_ and _b_ the calcareous part is unshaded.] - -To understand Archæocyathus, let us imagine an inverted cone of -carbonate of lime from an inch or two to a foot in length, and with -its point buried in the mud at the bottom of the sea, while its open -cup extends upward into the water. The lower part buried in the soil -is composed of an irregular acervuline network of thick calcareous -plates, enclosing chambers communicating with one another (figs. 40 -and 41 A). Above this where the cup expands, its walls are composed -of thin outer and inner plates, perforated with innumerable holes, -and connected with each other by vertical plates, which are also -perforated with round pores, establishing a communication between the -radiating chambers into which they divide the thickness of the wall -(figs. 38, 39, and 41 B). In such a structure the chambers in the wall -of the cup and the irregular chambers of the base would be filled with -gelatinous animal matter, and the pseudopods would project from the -numerous pores in the inner and outer wall. In the older parts of the -skeleton, the structure is further complicated by the formation of -thin transverse plates, irregular in distribution, and where greater -strength is required a calcareous thickening is added, which in some -places shows a canal system like that of Eozoon (fig. 41, B, C).[AJ] -As compared with Eozoon, the fossils want its fine perforated wall, -but have a more regular plan of growth. There are fragments in the -Eozoon limestones which may have belonged to structures like these; -and when we know more of the deep sea of the Primordial, we may -recover true species of Eozoon from it, or may find forms intermediate -between it and Archæocyathus. In the meantime I know no nearer bond of -connection between Eozoon and the Primordial age than that furnished -by the ancient cup Zoophytes of Labrador, though I have searched very -carefully in the fossiliferous conglomerates of Cambrian age on the -Lower St. Lawrence, which contain rocks of all the formations from the -Laurentian upwards, often with characteristic fossils. I have also made -sections of many of the fossiliferous pebbles in these conglomerates -without finding any certain remains of such organisms, though the -fragments of the crusts of some of the Primordial tribolites, when -their tubuli are infiltrated with dark carbonaceous matter, are so like -the supplemental skeleton of Eozoon, that but for their forms they -might readily be mistaken for it; and associated with them are broken -pieces of other porous organisms which may belong to Protozoa, though -this is not yet certain. - -[Footnote AJ: On the whole these curious fossils, if regarded as -Foraminifera, are most nearly allied to the Orbitolites and Dactyloporæ -of the Early Tertiary period, as described by Carpenter.] - -Of all the fossils of the Silurian rocks those which most resemble -Eozoon are the _Stromatoporæ_, or "layer-corals," whose resemblance -to the old Laurentian fossil at once struck Sir William Logan; and -these occur in the earliest great oceanic limestones which succeed the -Primordial period, those of the Trenton group, in the Siluro-Cambrian. -From this they extend upward as far as the Devonian, appearing -everywhere in the limestones, and themselves often constituting large -masses of calcareous rock. Our figure (fig. 42) shows a small example -of one of these fossils; and when sawn asunder or broken across and -weathered, they precisely resemble Eozoon in general appearance, -especially when, as sometimes happens, their cell-walls have been -silicified. - -[Illustration: Fig. 42. _Stromatopora rugosa, Hall--Lower Silurian, -Canada._ (_After Billings._) - -The specimen is of smaller size than usual, and is silicified. It is -probably inverted in position, and the concentric marks on the outer -surface are due to concretions of silica.] - -There are, however, different types of these fossils. The most common, -the Stromatoporæ properly so called, consist of concentric layers of -calcareous matter attached to each other by pillar-like processes, -which, as well as the layers, are made up of little threads of -limestone netted together, or radiating from the tops and bottoms of -the pillars, and forming a very porous substance. Though they have -been regarded as corals by some, they are more generally believed -to be Protozoa; but whether more nearly allied to sponges or to -Foraminifera may admit of doubt. Some of the more porous kinds are -not very dissimilar from calcareous sponges, but they generally want -true oscula and pores, and seem better adapted to shield the gelatinous -body of a Foraminifer projecting pseudopods in search of food, than -that of a sponge, living by the introduction of currents of water. Many -of the denser kinds, however, have their calcareous floors so solid -that they must be regarded as much more nearly akin to Foraminifers, -and some of them have the same irregular inosculation of these floors -observed in Eozoon. Figs. 43, A to D, show portions of species of -this description, in which the resemblance to Eozoon in structure and -arrangement of parts is not remote. - -[Illustration: Fig. 43. _Structures of Stromatopora._ - -(_a._) Portion of an oblique section magnified, showing laminæ and -columns. (_b._) Portion of wall with pores, and crusted on both sides -with quartz crystals. (_c._) Thickened portion of wall with canals. -(_d._) Portion of another specimen, showing irregular laminæ and -pillars.] - -These fossils, however, show no very distinct canal system or -supplemental skeleton, but this also appears in those forms which have -been called Caunopora or CÅ“nostroma. In these the plates are traversed -by tubes, or groups of tubes, which in each successive floor give out -radiating and branching canals exactly like those of Eozoon, though -more regularly arranged; and if we had specimens with the canals -infiltrated with glauconite or serpentine, the resemblance would be -perfect. When, as in figs. 44 and 45 A, these canals are seen on the -abraded surface, they appear as little grooves arranged in stars, -which resemble the radiating plates of corals, but this resemblance -is altogether superficial, and I have no doubt that they are really -foraminiferal organisms. This will appear more distinctly from the -sections in fig. 45 B, C, which represents an undescribed species -recently found by Mr. Weston, in the Upper Silurian limestone of -Ontario. - -[Illustration: Fig. 44. _Caunopora planulata, Hall--Devonian; showing -the radiating canals on a weathered surface._ (_After Hall._)] - -[Illustration: Fig. 45. _CÅ“nostroma--Guelph Limestone, Upper Silurian, -from a specimen collected by Mr. Weston, showing the canals._ - -(_a._) Surface with canals, natural size. (_b._) Vertical section, -natural size. (_c._) The same magnified, showing canals and laminæ.] - -There are probably many species of these curious fossils, but their -discrimination is difficult, and their nomenclature confused, so that -it would not be profitable to engage the attention of the reader -with it except in a note. Their state of preservation, however, is -so highly illustrative of that of Eozoon that a word as to this -will not be out of place. They are sometimes preserved merely by -infiltration with calcite or dolomite, and in this case it is most -difficult to make out their minute structures. Often they appear -merely as concentrically laminated masses which, but for their mode -of occurrence, might be regarded as mere concretions. In other cases -the cell-walls and pillars are perfectly silicified, and then they -form beautiful microscopic objects, especially when decalcified with -an acid. In still other cases, they are preserved like Eozoon, the -walls being calcareous and the chambers filled with silica. In this -state when weathered or decalcified they are remarkably like Eozoon, -but I have not met with any having their minute pores and tubes so -well preserved as in some of the Laurentian fossils. In many of them, -however, the growth and overlapping of the successive amÅ“ba-like coats -of sarcode can be beautifully seen, exactly as on the surface of a -decalcified piece of Eozoon. Those in my collection which most nearly -resemble the Laurentian specimens are from the older part of the Lower -Silurian series; but unfortunately their minute structures are not well -preserved. - -In the Silurian and Devonian ages, these Stromatoporæ evidently carried -out the same function as the Eozoon in the Laurentian. Winchell tells -us that in Michigan and Ohio single specimens can be found several feet -in diameter, and that they constitute the mass of considerable beds of -limestone. I have myself seen in Canada specimens a foot in diameter, -with a great number of laminæ. Lindberg[AK] has given a most vivid -account of their occurrence in the Isle of Gothland. He says that they -form beds of large irregular discs and balls, attaining a thickness of -five Swedish feet, and traceable for miles along the coast, and the -individual balls are sometimes a yard in diameter. In some of them the -structure is beautifully preserved. In others, or in parts of them, -it is reduced to a mass of crystalline limestone. This species is of -the CÅ“nostroma type, and is regarded by Lindberg as a coral, though -he admits its low type and resemblance to Protozoa. Its continuous -calcareous skeleton he rightly regards as fatal to its claim to be a -true sponge. Such a fossil, differing as it does in minute points of -structure from Eozoon, is nevertheless probably allied to it in no very -distant way, and a successor to its limestone-making function. Those -which most nearly approach to Foraminifera are those with thick and -solid calcareous laminæ, and with a radiating canal system; and one -of the most Eozoon-like I have seen, is a specimen of the undescribed -species already mentioned from the Guelph (Upper Silurian) limestone -of Ontario, collected by Mr. Weston, and now in the Museum of the -Geological Survey. I have attempted to represent its structures in fig. -44. - -[Footnote AK: _Transactions of Swedish Academy_, 1870.] - -[Illustration: Fig. 46. _Receptaculites, restored._ (_After Billings._) - -(_a._) Aperture. (_b._) Inner wall. (_c._) Outer wall. (_n._) Nucleus, -or primary chamber. (_v._) Internal cavity.] - -[Illustration: Fig. 47. _Diagram of Wall and Tubes of Receptaculites._ -(_After Billings._) - -(_b._) Inner wall. (_c._) Outer wall. (_d._) Section of plates. (_e._) -Pore of inner wall. (_f._) Canal of inner wall. (_g._) Radial stolon. -(_h._) Cyclical stolon. (_k._) Suture of plates of outer wall.] - -[Illustration: Fig. 48. _Receptaculites, Inner Surface of Outer Wall -with the Stolons remaining on its Surface._ (_After Billings._)] - -In the rocks extending from the Lower Silurian and perhaps from the -Upper Cambrian to the Devonian inclusive, the type and function of -Eozoon are continued by the Stromatoporæ, and in the earlier part of -this time these are accompanied by the Archæocyathids, and by another -curious form, more nearly allied to the latter than to Eozoon, the -_Receptaculites_. These curious and beautiful fossils, which sometimes -are a foot in diameter, consist, like Archæocyathus, of an outer and -inner coat enclosing a cavity; but these coats are composed of square -plates with pores at the corners, and they are connected by hollow -pillars passing in a regular manner from the outer to the inner coat. -They have been regarded by Salter as Foraminifers, while Billings -considers their nearest analogues to be the seed-like germs of some -modern silicious sponges. On the whole, if not Foraminifera, they must -have been organisms intermediate between these and sponges, and they -certainly constitute one of the most beautiful and complex types of -the ancient Protozoa, showing the wonderful perfection to which these -creatures attained at a very early period. (Figs. 46, 47, 48.) - -I might trace these ancient forms of foraminiferal life further up in -the geological series, and show how in the Carboniferous there are -nummulitic shells conforming to the general type of Eozoon, and in some -cases making up the mass of great limestones.[AL] Further, in the great -chalk series and its allied beds, and in the Lower Tertiary, there are -not only vast foraminiferal limestones, but gigantic species reminding -us of Stromatopora and Eozoon.[AM] Lastly, more diminutive species are -doing similar work on a great scale in the modern ocean. Thus we may -gather up the broken links of the chain of foraminiferal life, and -affirm that Eozoon has never wanted some representative to uphold its -family and function throughout all the vast lapse of geological time. - -[Footnote AL: _Fusulina_, as recently described by Carpenter, -_Archæodiscus_ of Brady, and the Nummulite recently found in the -Carboniferous of Belgium.] - -[Footnote AM: _Parkeria_ and _Loftusia_ of Carpenter.] - - -NOTES TO CHAPTER VI. - -(A.) Stromatoporidæ, Etc. - - For the best description of Archæocyathus, I may refer to _The - Palæozoic Fossils of Canada_, by Mr. Billings, vol. i. There also, - and in Mr. Salter's memoir in _The Decades of the Canadian Survey_, - will be found all that is known of the structure of Receptaculites. - For the American Stromatoporæ I may refer to Winchell's paper in the - _Proceedings of the American Association_, 1866; to Professor Hall's - Descriptions of New Species of Fossils from Iowa, _Report of the - State Cabinet, Albany_, 1872; and to the Descriptions of Canadian - Species by Dr. Nicholson, in his _Report on the Palæontology of - Ontario_, 1874. - - The genus Stromatopora of Goldfuss was defined by him as consisting - of laminæ of a solid and porous character, alternating and - contiguous, and constituting a hemispherical or sub-globose mass. - In this definition, the porous strata are really those of the - fossil, the alternating solid strata being the stony filling of the - chambers; and the descriptions of subsequent authors have varied - according as, from the state of preservation of the specimens or - other circumstances, the original laminæ or the filling of the spaces - attracted their attention. In the former case the fossil could be - described as consisting of laminæ made up of interlaced fibrils of - calcite, radiating from vertical pillars which connect the laminæ. - In the latter case, the laminæ, appear as solid plates, separated - by very narrow spaces, and perforated with round vertical holes - representing the connecting pillars. These Stromatoporæ range from - the Lower Silurian to the Devonian, inclusive, and many species have - been described; but their limits are not very definite, though there - are undoubtedly remarkable differences in the distances of the laminæ - and in their texture, and in the smooth or mammillated character - of the masses. Hall's genus Stromatocerium belongs to these forms, - and D'Orbigny's genus Sparsispongia refers to mammillated species, - sometimes with apparent oscula. - - Phillip's genus Caunopora was formed to receive specimens with - concentric cellular layers traversed by "long vermiform cylindrical - canals;" while Winchell's genus CÅ“nostroma includes species with - these vermiform canals arranged in a radiate manner, diverging from - little eminences in the concentric laminæ. The distinction between - these last genera does not seem to be very clear, and may depend - on the state of preservation of the specimens. A more important - distinction appears to exist between those that have a single - vertical canal from which the subordinate canals diverge, and those - that have groups of such canals. - - Some species of the CÅ“nostroma group have very dense calcareous - laminæ traversed by the canals; but it does not seem that any - distinction has yet been made between the proper wall and the - intermediate skeleton; and most observers have been prevented from - attending to such structures by the prevailing idea that these - fossils are either corals or sponges, while the state of preservation - of the more delicate tissues is often very imperfect. - - -(B.) Localities of Eozoon, or of Limestones supposed to contain it. - - In Canada the principal localities of Eozoon Canadense are at - Grenville, Petite Nation, the Calumets Rapids, Burgess, Tudor, and - Madoc. At the two last places the fossil occurs in beds which may be - on a somewhat higher horizon than the others. Mr. Vennor has recently - found specimens which have the general form of Eozoon, though the - minute structure is not preserved, at Dalhousie, in Lanark Co., - Ontario. One specimen from this place is remarkable from having been - mineralized in part by a talcose mineral associated with serpentine. - - I have examined specimens from Chelmsford, in Massachusetts, and from - Amity and Warren County, New York, the latter from the collection of - Professor D. S. Martin, which show the canals of Eozoon in a fair - state of preservation, though the specimens are fragmental, and do - not show the laminated structure. - - In European specimens of limestones of Laurentian age, from Tunaberg - and Fahlun in Sweden, and from the Western Islands of Scotland, I - have hitherto failed to recognise the characteristic structure of - the fossil. Connemara specimens have also failed to afford me any - satisfactory results, and specimens of a serpentine limestone from - the Alps, collected by M. Favre, and communicated to me by Dr. Hunt, - though in general texture they much resemble acervuline Eozoon, do - not show its minute structures. - -[Illustration: - Plate VII. - - _Untouched nature-print of part of a large specimen of Eozoon, from - Petite Nation._ - -The lighter portions are less perfect than in the original, owing to -the finer laminæ of serpentine giving way. The dark band at one side is -one of the deep lacunæ or oscula.] - - - - -CHAPTER VII. - -OPPONENTS AND OBJECTIONS. - - -The active objectors to the animal nature of Eozoon have been few, -though some of them have returned to the attack with a pertinacity and -determination which would lead one to believe that they think the most -sacred interests of science to be dependent on the annihilation of this -proto-foraminifer. I do not propose here to treat of the objections in -detail. I have presented the case of Eozoon on its own merits, and on -these it must stand. I may merely state that the objectors strive to -account for the existence of Eozoon by purely mineral deposition, and -that the complicated changes which they require to suppose are perhaps -the strongest indirect evidence for the necessity of regarding the -structures as organic. The reader who desires to appreciate this may -consult the notes to this chapter.[AN] - -[Footnote AN: Also Rowney and King's papers in _Journal Geological -Society_, August, 1866; and _Proceedings Irish Academy_, 1870 and 1871.] - -I confess that I feel disposed to treat very tenderly the position of -objectors. The facts I have stated make large demands on the faith -of the greater part even of naturalists. Very few geologists or -naturalists have much knowledge of the structure of foraminiferal -shells, or would be able under the microscope to recognise them with -certainty. Nor have they any distinct ideas of the appearances of such -structures under different kinds of preservation and mineralisation. -Further, they have long been accustomed to regard the so-called Azoic -rocks as not only destitute of organic remains, but as being in such -a state of metamorphism that these could not have been preserved had -they existed. Few, therefore, are able intelligently to decide for -themselves, and so they are called on to trust to the investigations -of others, and on their testimony to modify in a marked degree their -previous beliefs as to the duration of life on our planet. In these -circumstances it is rather wonderful that the researches made with -reference to Eozoon have met with so general acceptance, and that the -resurrection of this ancient inhabitant of the earth has not aroused -more of the sceptical tendency of our age. - -It must not be lost sight of, however, that in such cases there may -exist a large amount of undeveloped and even unconscious scepticism, -which shows itself not in active opposition, but merely in quietly -ignoring this great discovery, or regarding it with doubt, as an -uncertain or unestablished point in science. Such scepticism may best -be met by the plain and simple statements in the foregoing chapters, -and by the illustrations accompanying them. It may nevertheless be -profitable to review some of the points referred to, and to present -some considerations making the existence of Laurentian life less -anomalous than may at first sight be supposed. One of these is the -fact that the discovery of Eozoon brings the rocks of the Laurentian -system into more full harmony with the other geological formations. It -explains the origin of the Laurentian limestones in consistency with -that of similar rocks in the later periods, and in like manner it helps -us to account for the graphite and sulphides and iron ores of these old -rocks. It shows us that no time was lost in the introduction of life -on the earth. Otherwise there would have been a vast lapse of time in -which, while the conditions suitable to life were probably present, no -living thing existed to take advantage of these conditions. Further, it -gives a more simple beginning of life than that afforded by the more -complex fauna of the Primordial age; and this is more in accordance -with what we know of the slow and gradual introduction of new forms of -living things during the vast periods of Palæozoic time. In connection -with this it opens a new and promising field of observation in the -older rocks, and if this should prove fertile, its exploration may -afford a vast harvest of new forms to the geologists of the present and -coming time. This result will be in entire accordance with what has -taken place before in the history of geological discovery. It is not -very long since the old and semi-metamorphic sediments constituting the -great Silurian and Cambrian systems were massed together in geological -classifications as primitive or primary rocks, destitute or nearly -destitute of organic remains. The brilliant discoveries of Sedgwick, -Murchison, Barrande, and a host of others, have peopled these once -barren regions; and they now stretch before our wondering gaze in -the long vistas of early Palæozoic life. So we now look out from the -Cambrian shore upon the vast ocean of the Huronian and Laurentian, -all to us yet tenantless, except for the few organisms, which, like -stray shells cast upon the beach, or a far-off land dimly seen in the -distance, incite to further researches, and to the exploration of the -unknown treasures that still lie undiscovered. It would be a suitable -culmination of the geological work of the last half-century, and one -within reach at least of our immediate successors, to fill up this -great blank, and to trace back the Primordial life to the stage of -Eozoon, and perhaps even beyond this, to predecessors which may have -existed at the beginning of the Lower Laurentian, when the earliest -sediments of that great formation were laid down. Vast unexplored areas -of Laurentian and Huronian rocks exist in the Old World and the New. -The most ample facilities for microscopic examination of rocks may -now be obtained; and I could wish that one result of the publication -of these pages may be to direct the attention of some of the younger -and more active geologists to these fields of investigation. It is to -be observed also that such regions are among the richest in useful -minerals, and there is no reason why search for these fossils should -not be connected with other and more practically useful researches. On -this subject it will not be out of place to quote the remarks which I -made in one of my earlier papers on the Laurentian fossils:-- - -"This subject opens up several interesting fields of chemical, -physiological, and geological inquiry. One of these relates to the -conclusions stated by Dr. Hunt as to the probable existence of a -large amount of carbonic acid in the Laurentian atmosphere, and of -much carbonate of lime in the seas of that period, and the possible -relation of this to the abundance of certain low forms of plants and -animals. Another is the comparison already instituted by Professor -Huxley and Dr. Carpenter, between the conditions of the Laurentian and -those of the deeper parts of the modern ocean. Another is the possible -occurrence of other forms of animal life than Eozoon and Annelids, -which I have stated in my paper of 1864, after extensive microscopic -study of the Laurentian limestones, to be indicated by the occurrence -of calcareous fragments, differing in structure from Eozoon, but at -present of unknown nature. Another is the effort to bridge over, by -further discoveries similar to that of the _Eozoon Bavaricum_ of -Gümbel, the gap now existing between the life of the Lower Laurentian -and that of the Primordial Silurian or Cambrian period. It is scarcely -too much to say that these inquiries open up a new world of thought and -investigation, and hold out the hope of bringing us into the presence -of the actual origin of organic life on our planet, though this may -perhaps be found to have been Prelaurentian. I would here take the -opportunity of stating that, in proposing the name Eozoon for the -first fossil of the Laurentian, and in suggesting for the period the -name "Eozoic," I have by no means desired to exclude the possibility -of forms of life which may have been precursors of what is now to us -the dawn of organic existence. Should remains of still older organisms -be found in those rocks now known to us only by pebbles in the -Laurentian, these names will at least serve to mark an important stage -in geological investigation." - -But what if the result of such investigations should be to produce -more sceptics, or to bring to light mineral structures so resembling -Eozoon as to throw doubt upon the whole of the results detailed in -these chapters? I can fancy that this might be the first consequence, -more especially if the investigations were in the hands of persons -more conversant with minerals than with fossils; but I see no reason -to fear the ultimate results. In any case, no doubt, the value of the -researches hitherto made may be diminished. It is always the fate of -discoverers in Natural Science, either to be followed by opponents who -temporarily or permanently impugn or destroy the value of their new -facts, or by other investigators who push on the knowledge of facts and -principles so far beyond their standpoint that the original discoveries -are cast into the shade. This is a fatality incident to the progress of -scientific work, from which no man can be free; and in so far as such -matters are concerned, we must all be content to share the fate of the -old fossils whose history we investigate, and, having served our day -and generation to give place to others. If any part of our work should -stand the fire of discussion let us be thankful. One thing at least is -certain, that such careful surveys as those in the Laurentian rocks -of Canada which led to the discovery of Eozoon, and such microscopic -examinations as those by which it has been worked up and presented to -the public, cannot fail to yield good results of one kind or another. -Already the attention excited by the controversies about Eozoon, by -attracting investigators to the study of various microscopic and -imitative forms in rocks, has promoted the advancement of knowledge, -and must do so still more. For my own part, though I am not content to -base all my reputation on such work as I have done with respect to this -old fossil, I am willing at least to take the responsibility of the -results I have announced, whatever conclusions may be finally reached; -and in the consciousness of an honest effort to extend the knowledge -of nature, to look forward to a better fame than any that could result -from the most successful and permanent vindication of every detail -of our scientific discoveries, even if they could be pushed to a -point which no subsequent investigation in the same difficult line of -research would be able to overpass. - -Contenting myself with these general remarks, I shall, for the benefit -of those who relish geological controversy, append to this chapter a -summary of the objections urged by the most active opponents of the -animal nature of Eozoon, with the replies that may be or have been -given; and I now merely add (in fig. 49) a magnified camera tracing of -a portion of a lamina of Eozoon with its canals and tubuli, to show -more fully the nature of the structures in controversy. - -[Illustration: Fig. 49. _Portion of a thin Transverse Slice of a Lamina -of Eozoon, magnified, showing its structure, as traced with the camera._ - -(_a._) Nummuline wall of under side. (_b._) Intermediate skeleton with -canals. (_a´._) Nummuline wall of upper side. The two lower figures -show the lower and upper sides more highly magnified. The specimen is -one in which the canals are unusually well seen.] - -It may be well, however, to sum up the evidence as it has been -presented by Sir W. E. Logan, Dr. Carpenter, Dr. Hunt, and the author, -in a short and intelligible form; and I shall do so under a few brief -heads, with some explanatory remarks:-- - -1. The Lower Laurentian of Canada, a rock formation whose -distribution, age, and structure have been thoroughly worked out by -the Canadian Survey, is found to contain thick and widely distributed -beds of limestone, related to the other beds in the same way in which -limestones occur in the sediments of other geological formations. There -also occur in the same formation, graphite, iron ores, and metallic -sulphides, in such relations as to suggest the idea that the limestones -as well as these other minerals are of organic origin. - -2. In the limestones are found laminated bodies of definite form and -structure, composed of calcite alternating with serpentine and other -minerals. The forms of these bodies suggested a resemblance to the -Silurian Stromatoporæ, and the different mineral substances associated -with the calcite in the production of similar forms, showed that these -were not accidental or concretionary. - -3. On microscopic examination, it proved that the calcareous laminæ -of these forms were similar in structure to the shells of modern -and fossil Foraminifera, more especially those of the Rotaline and -Nummuline types, and that the finer structures, though usually filled -with serpentine and other hydrous silicates, were sometimes occupied -with calcite, pyroxene, or dolomite, showing that they must when recent -have been empty canals and tubes. - -4. The mode of filling thus suggested for the chambers and tubes of -Eozoon, is precisely that which takes place in modern Foraminifera -filled with glauconite, and in Palæozoic crinoids and corals filled -with other hydrous silicates. - -5. The type of growth and structure predicated of Eozoon from the -observed appearances, in its great size, its laminated and acervuline -forms, and in its canal system and tubulation, are not only in -conformity with those of other Foraminifera, but such as might be -expected in a very ancient form of that group. - -6. Indications exist of other organic bodies in the limestones -containing Eozoon, and also of the Eozoon being preserved not only in -reefs but in drifted fragmental beds as in the case of modern corals. - -7. Similar organic structures have been found in the Laurentian -limestones of Massachusetts and New York, and also in those of various -parts of Europe, and Dr. Gümbel has found an additional species in -rocks succeeding the Laurentian in age. - -8. The manner in which the structures of Eozoon are affected by the -faulting, development of crystals, mineral veins, and other effects of -disturbance and metamorphism in the containing rocks, is precisely that -which might be expected on the supposition that it is of organic origin. - -9. The exertions of several active and able opponents have failed to -show how, otherwise than by organic agency, such structures as those -of Eozoon can be formed, except on the supposition of pseudomorphism -and replacement, which must be regarded as chemically extravagant, and -which would equally impugn the validity of all fossils determined -by microscopic structure. In like manner all comparisons of these -structures with dendritic and other imitative forms have signally -failed, in the opinion of those best qualified to judge. - -Another and perhaps simpler way of putting the case is the -following:--Only three general modes of accounting for the existence -of Eozoon have been proposed. The first is that of Professors King and -Rowney, who regard the chambers and canals filled with serpentine as -arising from the erosion or partial dissolving away of serpentine and -its replacement by calcite. The objections to this are conclusive. -It does not explain the nummuline wall, which has to be separately -accounted for by confounding it, contrary to the observed facts, -with the veins of fibrous serpentine which actually pass through -cracks in the fossil. Such replacement is in the highest degree -unlikely on chemical grounds, and there is no evidence of it in the -numerous serpentine grains, nodules, and bands in the Laurentian -limestones. On the other hand, the opposite replacement, that of -limestone by serpentine, seems to have occurred. The mechanical -difficulties in accounting for the delicate canals on this theory are -also insurmountable. Finally, it does not account for the specimens -preserved in pyroxene and other silicates, and in dolomite and calcite. -A second mode of accounting for the facts is that the Eozoon forms are -merely peculiar concretions. But this fails to account for their great -difference from the other serpentine concretions in the same beds, and -for their regularity of plan and the delicacy of their structure, and -also for minerals of different kinds entering into their composition, -and still presenting precisely the same forms and structures. The only -remaining theory is that of the filling of cavities by infiltration -with serpentine. This accords with the fact that such infiltration by -minerals akin to serpentine exists in fossils in later rocks. It also -accords with the known aqueous origin of the serpentine nodules and -bands, the veins of fibrous serpentine, and the other minerals found -filling the cavities of Eozoon. Even the pyroxene has been shown by -Hunt to exist in the Laurentian in veins of aqueous origin. The only -difficulty existing on this view is how a calcite skeleton with such -chambers, canals, and tubuli could be formed; and this is solved by the -discovery that all these facts correspond precisely with those to be -found in the shells of modern oceanic Foraminifera. The existence then -of Eozoon, its structure, and its relations to the containing rocks and -minerals being admitted, no rational explanation of its origin seems at -present possible other than that advocated in the preceding pages. - -If the reader will now turn to Plate VIII., page 207, he will find some -interesting illustrations of several very important facts bearing on -the above arguments. Fig. 1 represents a portion of a very thin slice -of a specimen traversed by veins of fibrous serpentine or chrysotile, -and having the calcite of the walls more broken by cleavage planes -than usual. The portion selected shows a part of one of the chambers -filled with serpentine, which presents the usual curdled aspect -almost impossible to represent in a drawing (_s_). It is traversed -by a branching vein of chrysotile (_s_´), which, where cut precisely -parallel to its fibres, shows clear fine cross lines, indicating the -sides of its constituent prisms, and where the plane of section has -passed obliquely to its fibres, has a curiously stippled or frowsy -appearance. On either side of the serpentine band is the nummuline -or proper wall, showing under a low power a milky appearance, which, -with a higher power, becomes resolved into a tissue of the most -beautiful parallel threads, representing the filling of its tubuli. -Nothing can be more distinct than the appearances presented by this -wall and the chrysotile vein, under every variety of magnifying power -and illumination; and all who have had an opportunity of examining my -specimens have expressed astonishment that appearances so dissimilar -should have been confounded with each other. On the lower side two -indentations are seen in the proper wall (_c_). These are connected -with the openings into small subordinate chamberlets, one of which is -in part included in the thickness of the slice. At the upper and lower -parts of the figure are seen portions of the intermediate skeleton -traversed by canals, which in the lower part are very large, though -from the analogy of other specimens it is probable that they have in -their interstices minute canaliculi not visible in this slice. Fig. -2, from the same specimen, shows the termination of one of the canals -against the proper wall, its end expanding into a wide disc of sarcode -on the surface of the wall, as may be seen in similar structures in -modern Foraminifera. In this specimen the canals are beautifully smooth -and cylindrical, but they sometimes present a knotted or jointed -appearance, especially in specimens decalcified by acids, in which -perhaps some erosion has taken place. They are also occasionally -fringed with minute crystals, especially in those specimens in which -the calcite has been partially replaced with other minerals. Fig. 3 -shows an example of faulting of the proper wall, an appearance not -infrequently observed; and it also shows a vein chrysotile crossing the -line of fault, and not itself affected by it--a clear evidence of its -posterior origin. Figs. 4 and 5 are examples of specimens having the -canals filled with dolomite, and showing extremely fine canals in the -interstices of the others: an appearance observed only in the thicker -parts of the skeleton, and when these are very well preserved. These -dolomitized portions require some precautions for their observation, -either in slices or decalcified specimens, but when properly managed -they show the structures in very great perfection. The specimen in fig. -5 is from an abnormally thick portion of intermediate skeleton, having -unusually thick canals, and referred to in a previous chapter. - -One object which I have in view in thus minutely directing attention -to these illustrations, is to show the nature of the misapprehensions -which may occur in examining specimens of this kind, and at the same -time the certainty which may be attained when proper precautions are -taken. I may add that such structures as those referred to are best -seen in extremely thin slices, and that the observer must not expect -that every specimen will exhibit them equally well. It is only by -preparing and examining many specimens that the best results can be -obtained. It often happens that one specimen is required to show well -one part of the structures, and a different one to show another; and -previous to actual trial, it is not easy to say which portion of -the structures any particular fragment will show most clearly. This -renders it somewhat difficult to supply one's friends with specimens. -Really good slices can be prepared only from the best material and by -skilled manipulators; imperfect slices may only mislead; and rough -specimens may not be properly prepared by persons unaccustomed to the -work, or if so prepared may not turn out satisfactory, or may not be -skilfully examined. These difficulties, however, Eozoon shares with -other specimens in micro-geology, and I have experienced similar -disappointments in the case of fossil wood. - -In conclusion of this part of the subject, and referring to the notes -appended to this chapter for further details, I would express the hope -that those who have hitherto opposed the interpretation of Eozoon as -organic, and to whose ability and honesty of purpose I willingly bear -testimony, will find themselves enabled to acknowledge at least the -reasonable probability of that interpretation of these remarkable forms -and structures. - - -NOTES TO CHAPTER VII. - -(A.) Objections of Profs. King and Rowney. - -_Trans. Royal Irish Academy, July, 1869._[AO] - -[Footnote AO: Reprinted in the _Annals and Magazine of Natural -History_, May, 1874.] - - The following summary, given by these authors, may be taken as - including the substance of their objections to the animal nature of - Eozoon. I shall give them in their words and follow them with short - answers to each. - - "1st. The serpentine in ophitic rocks has been shown to present - appearances which can only be explained on the view that it undergoes - structural and chemical changes, causing it to pass into variously - subdivided states, and etching out the resulting portions into a - variety of forms--grains and plates, with lobulated or segmented - surfaces--fibres and aciculi--simple and branching configurations. - Crystals of malacolite, often associated with the serpentine, - manifest some of these changes in a remarkable degree. - - "2nd. The 'intermediate skeleton' of Eozoon (which we hold to be - the calcareous matrix of the above lobulated grains, etc.) is - completely paralleled in various crystalline rocks--notably marble - containing grains of coccolite (Aker and Tyree), pargasite (Finland), - chondrodite (New Jersey, etc.) - - "3rd. The 'chamber casts' in the acervuline variety of Eozoon are - more or less paralleled by the grains of the mineral silicates in the - pre-cited marbles. - - "4th. The 'chamber casts' being composed occasionally of loganite and - malacolite, besides serpentine, is a fact which, instead of favouring - their organic origin, as supposed, must be held as a proof of their - having been produced by mineral agencies; inasmuch as these three - silicates have a close pseudomorphic relationship, and may therefore - replace one another in their naturally prescribed order. - - "5th. Dr. Gümbel, observing rounded, cylindrical, or tuberculated - grains of coccolite and pargasite in crystalline calcareous marbles, - considered them to be 'chamber casts,' or of organic origin. We have - shown that such grains often present crystalline planes, angles, and - edges; a fact clearly proving that they were originally simple or - compound crystals that have undergone external decretion by chemical - or solvent action. - - "6th. We have adduced evidences to show that the 'nummuline layer' in - its typical condition--that is, consisting of cylindrical aciculi, - separated by interspaces filled with calcite--has originated directly - from closely packed fibres; these from chrysotile or asbestiform - serpentine; this from incipiently fibrous serpentine; and the latter - from the same mineral in its amorphous or structureless condition. - - "7th. The 'nummuline layer,' in its typical condition, unmistakably - occurs in cracks or fissures, both in Canadian and Connemara ophite. - - "8th. The 'nummuline layer' is paralleled by the fibrous coat which - is occasionally present on the surface of grains of chondrodite. - - "9th. We have shown that the relative position of two superposed - asbestiform layers (an _upper_ and an _under_ 'proper wall'), and the - admitted fact of their component aciculi often passing continuously - and without interruption from one 'chamber cast' to another, to the - exclusion of the 'intermediate skeleton,' are totally incompatible - with the idea of the 'nummuline layer' having resulted from - pseudopodial tubulation. - - "10th. The so-called 'stolons' and 'passages of communication - exactly corresponding with those described in _Cycloclypeus_,' - have been shown to be tabular crystals and variously formed bodies, - belonging to different minerals, wedged crossways or obliquely in the - calcareous interspaces between the grains and plates of serpentine. - - "11th. The 'canal system' is composed of serpentine, or malacolite. - Its typical kinds in the first of these minerals may be traced in - all stages of formation out of plates, prisms, and other solids, - undergoing a process of superficial decretion. Those in malacolite - are made up of crystals--single, or aggregated together--that have - had their planes, angles, and edges rounded off; or have become - further reduced by some solvent. - - "12th. The 'canal system' in its remarkable branching varieties is - completely paralleled by crystalline configurations in the coccolite - marble of Aker, in Sweden; and in the crevices of a crystal of spinel - imbedded in a calcitic matrix from Amity, New York. - - "13th. The _configurations_, presumed to represent the 'canal - systems,' are _totally without any regularity_ of form, of relative - size, or of arrangement; and they occur independently of and apart - from other 'eozoonal features' (Amity, Boden, etc.); facts not only - demonstrating them to be purely mineral products, but which strike at - the root of the idea that they are of organic origin. - - "14th. In answer to the argument that as all the foregoing 'eozoonal - features' are occasionally found together in ophite, the combination - must be considered a conclusive evidence of their organic origin, - we have shown, from the composition, physical characters, and - circumstances of occurrence and association of their component - serpentine, that they represent the structural and chemical changes - which are eminently and peculiarly characteristic of this mineral. - It has also been shown that the combination is paralleled to a - remarkable extent in chondrodite and its calcitic matrix. - - "15th. The 'regular alternation of lamellæ of calcareous and - silicious minerals' (respectively representing the 'intermediate - skeleton' and 'chamber casts') occasionally seen in ophite, and - considered to be a 'fundamental fact' evidencing an organic - arrangement, is proved to be a _mineralogical_ phenomenon by the - fact that a similar alternation occurs in amphiboline-calcitic - marbles, and gneissose rocks. - - "16th. In order to account for certain _untoward_ difficulties - presented by the configurations forming the 'canal system,' and - the aciculi of the 'nummuline layer'--that is, when they occur as - '_solid bundles_'--or are '_closely packed_'--or '_appear to be - glued together_'--Dr. Carpenter has proposed the theory that the - sarcodic extensions which they are presumed to represent have been - 'turned into stone' (a 'silicious mineral') 'by Nature's cunning' - ('just as the sarcodic layer on the surface of the shell of living - Foraminifers is formed by the spreading out of _coalesced_ bundles - of the pseudopodia that have emerged from the chamber wall')--'by - a process of chemical substitution _before_ their destruction by - ordinary decomposition.' We showed this quasi-alchymical theory to be - altogether unscientific. - - "17th. The 'silicious mineral' (serpentine) has been analogued with - those forming the variously-formed casts (in 'glauconite,' etc.) - of recent and fossil Foraminifers. We have shown that the mineral - silicates of Eozoon have no relation whatever to the substances - composing such casts. - - "18th. Dr. Hunt, in order to account for the serpentine, loganite, - and malacolite, being the presumed in-filling substances of Eozoon, - has conceived the 'novel doctrine,' that such minerals were - _directly_ deposited in the ocean waters in which this 'fossil' - lived. We have gone over all his evidences and arguments without - finding _one_ to be substantiated. - - "19th. Having investigated the alleged cases of 'chambers' and - 'tubes' occurring 'filled with calcite,' and presumed to be 'a - conclusive answer to' our 'objections,' we have shown that there are - the strongest grounds for removing them from the category of reliable - evidences on the side of the organic doctrine. The Tudor specimen has - been shown to be equally unavailable. - - "20th. The occurrence of the best preserved specimens of Eozoon - Canadense in rocks that are in a '_highly crystalline condition_' - (Dawson) must be accepted as a fact utterly fatal to its organic - origin. - - "21st. The occurrence of 'eozoonal features' _solely_ in crystalline - or metamorphosed rocks, belonging to the Laurentian, the Lower - Silurian, and the Liassic systems--never in ordinary unaltered - deposits of these and the intermediate systems--must be assumed as - completely demonstrating their purely mineral origin." - - The answers already given to these objections may be summed up - severally as follows:-- - - 1st. This is a mere hypothesis to account for the forms presented by - serpentine grains and by Eozoon. Hunt has shown that it is untenable - chemically, and has completely exploded it in his recent papers on - Chemistry and Geology.[AP] My own observations show that it does not - accord with the mode of occurrence of serpentine in the Laurentian - limestones of Canada. - -[Footnote AP: Boston, 1874.] - - 2nd. Some of the things stated to parallel the intermediate skeleton - of Eozoon, are probably themselves examples of that skeleton. Others - have been shown to have no resemblance to it. - - 3rd. The words "more or less" indicate the precise value of this - statement, in a question of comparison between mineral and organic - structures. So the prismatic structure of satin-spar may be said - "more or less" to resemble that of a shell, or of the cells of a - Stenopora. - - 4th. This overlooks the filling of chamber casts with pyroxene, - dolomite, or limestone. Even in the case of loganite this objection - is of no value unless it can be applied equally to the similar - silicates which fill cavities of fossils[AQ] in the Silurian - limestones and in the green-sand. - -[Footnote AQ: See for a full discussion of this subject Dr. Hunt's -"Papers" above referred to.] - - 5th. Dr. Gümbel's observations are those of a highly skilled and - accurate observer. Even if crystalline forms appear in "chamber - casts," this is as likely to be a result of the injury of organic - structures by crystallization, as of the partial effacement of - crystals by other actions. Crystalline faces occur abundantly in many - undoubted fossil woods and corals; and crystals not unfrequently - cross and interfere with the structures in such specimens. - - 6th. On the contrary, the Canadian specimens prove clearly that the - veins of chrysotile have been filled subsequently to the existence of - Eozoon in its present state, and that there is no connection whatever - between them and the Nummuline wall. - - 7th. This I have never seen in all my examinations of Eozoon. The - writers must have mistaken veins of fibrous serpentine for the - nummuline wall. - - 8th. Only if such grains of chondrodite are themselves casts of - foraminiferal chambers. But Messrs. King and Rowney have repeatedly - figured mere groups of crystals as examples of the nummuline wall. - - 9th. Dr. Carpenter has shown that this objection depends on a - misconception of the structure of modern Foraminifera, which show - similar appearances. - - 10th. That disseminated crystals occur in the Eozoon limestones is a - familiar fact, and one paralleled in many other more or less altered - organic limestones. Foreign bodies also occur in the chambers filled - with loganite and other minerals; but these need not any more be - confounded with the pillars and walls connecting the laminæ than - the sand filling a dead coral with its lamellæ. Further, it is well - known that foreign bodies are often contained both in the testa and - chambers even of recent Foraminifera. - - 11th. The canal system is not always filled with serpentine or - malacolite; and when filled with pyroxene, dolomite, or calcite, the - forms are the same. The irregularities spoken of are perhaps more - manifest in the serpentine specimens, because this mineral has in - places encroached on or partially replaced the calcite walls. - - 12th. If this is true of the Aker marble, then it must contain - Eozoon; and specimens of the Amity limestone which I have examined, - certainly contain large fragments of Eozoon. - - 13th. The configuration of the canal system is quite definite, - though varying in coarseness and fineness. It is not known to occur - independently of the forms of Eozoon except in fragmental deposits. - - 14th. The argument is not that they are "occasionally found together - in ophite," but that they are found together in specimens preserved - by different minerals, and in such a way as to show that all these - minerals have filled chambers, canals, and tubuli, previously - existing in a skeleton of limestone. - - 15th. The lamination of Eozoon is not like that of any rock, but - a strictly limited and definite form, comparable with that of - Stromatopora. - - 16th. This I pass over, as a mere captious criticism of modes of - expression used by Dr. Carpenter. - - 17th. Dr. Hunt, whose knowledge of chemical geology should give - the greatest weight to his judgment, maintains the deposition of - serpentine and loganite to have taken place in a manner similar to - that of jollyte and glauconite in undoubted fossils: and this would - seem to be a clear deduction from the facts he has stated, and from - the chemical character of the substances. My own observations of the - mode of occurrence of serpentine in the Eozoon limestones lead me to - the same result. - - 18th. Dr. Hunt's arguments on the subject, as recently presented - in his _Papers on Chemistry and Geology_, need only be studied by - any candid and competent chemist or mineralogist to lead to a very - different conclusion from that of the objectors. - - 19th. This is a mere statement of opinion. The fact remains that the - chambers and canals are sometimes filled with calcite. - - 20th. That the occurrence of Eozoon in crystalline limestones is - "utterly fatal" to its claims to organic origin can be held only by - those who are utterly ignorant of the frequency with which organic - remains are preserved in highly crystalline limestones of all ages. - In addition to other examples mentioned above, I may state that the - curious specimen of CÅ“nostroma from the Guelph limestone figured - in Chapter VI., has been converted into a perfectly crystalline - dolomite, while its canals and cavities have been filled with - calcite, since weathered out. - - 21st. This limited occurrence is an assumption contrary to facts. - It leaves out of account the Tudor specimens, and also the abundant - occurrence of the Stromatoporoid successors of Eozoon in the - Silurian and Devonian. Further, even if the Eozoon were limited to - the Laurentian, this would not be remarkable; and since all the - Laurentian rocks known to us are more or less altered, it could not - in that case occur in unaltered rocks. - - I have gone over these objections seriatim, because, though - individually weak, they have an imposing appearance in the aggregate, - and have been paraded as a conclusive settlement of the questions - at issue. They have even been reprinted in the year just past in an - English journal of some standing, which professes to accept only - original contributions to science, but has deviated from its rule in - their favour. I may be excused for adding a portion of my original - argument in opposition to these objections, as given more at length - in the _Transactions of the Irish Academy_. - - 1. I object to the authors' mode of stating the question at issue, - whereby they convey to the reader the impression that this is merely - to account for the occurrence of certain peculiar forms in ophite. - - With reference to this, it is to be observed that the attention of - Sir William Logan, and of the writer, was first called to Eozoon - by the occurrence in Laurentian rocks of definite forms resembling - the Silurian _Stromatoporæ_, and dissimilar from any concretions or - crystalline structures found in these rocks. With his usual sagacity, - Sir William added to these facts the consideration that the mineral - substances occurring is these forms were so dissimilar as to suggest - that the forms themselves must be due to some extraneous cause rather - than to any crystalline or segregative tendency of their constituent - minerals. These specimens, which were exhibited by Sir William as - probably fossils, at the meeting of the American Association in - 1859, and noticed with figures in the Report of the Canadian Survey - for 1863, showed under the microscope no minute structures. The - writer, who had at the time an opportunity of examining them, stated - his belief that if fossils, they would prove to be not Corals but - Protozoa. - - In 1864, additional specimens having been obtained by the Survey, - slices were submitted to the writer, in which he at once detected - a well-marked canal-system, and stated, decidedly, his belief that - the forms were organic and foraminiferal. The announcement of this - discovery was first made by Sir W. E. Logan, in _Silliman's Journal_ - for 1864. So far, the facts obtained and stated related to definite - forms mineralised by loganite, serpentine, pyroxene, dolomite, and - calcite. But before publishing these facts in detail, extensive - series of sections of all the Laurentian limestones, and of those - of the altered Quebec group of the Green Mountain range, were made, - under the direction of Sir W. E. Logan and Dr. Hunt, and examined - microscopically. Specimens were also decalcified by acids, and - subjected to chemical examination by Dr. Sterry Hunt. The result was - the conviction that the definite laminated forms must be organic, - and further, that there exist in the Laurentian limestones fragments - of such forms retaining their structure, and also other fragments, - probably organic, but distinct from Eozoon. These conclusions were - submitted to the Geological Society of London, in 1864, after the - specimens on which they were based had been shown to Dr. Carpenter - and Professor T. R. Jones, the former of whom detected in some of - the specimens an additional foraminiferal structure--that of the - tubulation of the proper wall, which I had not been able to make out. - Subsequently, in rocks at Tudor, of somewhat later age than those - of the Lower Laurentian at Grenville, similar structures were found - in limestones not more metamorphic than many of those which retain - fossils in the Silurian system. I make this historical statement in - order to place the question in its true light, and to show that it - relates to the organic origin of certain definite mineral masses, - exhibiting, not only the external forms of fossils, but also their - internal structure. - - In opposition to these facts, and to the careful deductions drawn - from them, the authors of the paper under consideration maintain that - the structures are mineral and crystalline. I believe that in the - present state of science such an attempt to return to the doctrine - of "plastic-force" as a mode of accounting for fossils would not - be tolerated for a moment, were it not for the great antiquity and - highly crystalline condition of the rocks in which the structures - are found, which naturally create a prejudice against the idea of - their being fossiliferous. That the authors themselves feel this is - apparent from the slight manner in which they state the leading facts - above given, and from their evident anxiety to restrict the question - to the mode of occurrence of serpentine in limestone, and to ignore - the specimens of Eozoon preserved under different mineral conditions. - - 2. With reference to the general form of Eozoon and its structure - on the large scale, I would call attention to two admissions of - the authors of the paper, which appear to me to be fatal to their - case:--First, they admit, at page 533 [_Proceedings_, vol. x.], - their "inability to explain satisfactorily" the alternating layers - of carbonate of lime and other minerals in the typical specimens of - Canadian Eozoon. They make a feeble attempt to establish an analogy - between this and certain concentric concretionary layers; but the - cases are clearly not parallel, and the laminæ of the Canadian - Eozoon present connecting plates and columns not explicable on any - concretionary hypothesis. If, however, they are unable to explain the - lamellar structure alone, as it appeared to Logan in 1859, is it not - rash to attempt to explain it away now, when certain minute internal - structures, corresponding to what might have been expected on the - hypothesis of its organic origin, are added to it? If I affirm that - a certain mass is the trunk of a fossil tree, and another asserts - that it is a concretion, but professes to be unable to account for - its form and its rings of growth, surely his case becomes very weak - after I have made a slice of it, and have shown that it retains the - structure of wood. - - Next, they appear to admit that if specimens occur wholly composed - of carbonate of lime, their theory will fall to the ground. Now such - specimens do exist. They treat the Tudor specimen with scepticism as - probably "strings of segregated calcite." Since the account of that - specimen was published, additional fragments have been collected, so - that new slices have been prepared. I have examined these with care, - and am prepared to affirm that the chambers in these specimens are - filled with a dark-coloured limestone not more crystalline than is - usual in the Silurian rocks, and that the chamber walls are composed - of carbonate of lime, with the canals filled with the same material, - except where the limestone filling the chambers has penetrated into - parts of the larger ones. I should add that the stratigraphical - researches of Mr. Vennor, of the Canadian Survey, have rendered it - probable that the beds containing these fossils, though unconformably - underlying the Lower Silurian, overlie the Lower Laurentian of the - locality, and are, therefore, probably Upper Laurentian, or perhaps - Huronian, so that the Tudor specimens may approach in age to Gümbel's - Eozoon Bavaricum.[AR] - -[Footnote AR: I may now refer in addition to the canals filled with -calcite and dolomite, detected by Dr. Carpenter and myself in specimens -from Petite Nation, and mentioned in a previous chapter. See also Plate -VIII.] - - Further, the authors of the paper have no right to object to our - regarding the laminated specimen as "typical" Eozoon. If the question - were as to _typical ophite_ the case would be different; but the - question actually is as to certain well-defined forms which we regard - as fossils, and allege to have organic structure on the small scale, - as well as lamination on the large scale. We profess to account for - the acervuline forms by the irregular growth at the surface of the - organisms, and by the breaking of them into fragments confusedly - intermingled in great thicknesses of limestone, just as fragments of - corals occur in Palæozoic limestones; but we are under no obligation - to accept irregular or disintegrated specimens as typical; and when - objectors reason from these fragments, we have a right to point to - the more perfect examples. It would be easy to explain the loose - cells of _Tetradium_ which characterize the bird's-eye limestone - of the Lower Silurian of America, as crystalline structures; but - a comparison with the unbroken masses of the same coral, shows - their true nature. I have for some time made the minute structure - of Palæozoic limestones a special study, and have described some - of them from the Silurian formations of Canada.[AS] I possess now - many additional examples, showing fragments of various kinds of - fossils preserved in these limestones, and recognisable only by the - infiltration of their pores with different silicious minerals. It can - also be shown that in many cases the crystallization of the carbonate - of lime, both of the fossils themselves and of their matrix, has - not interfered with the perfection of the most minute of these - structures. - -[Footnote AS: In the _Canadian Naturalist_.] - - The fact that the chambers are usually filled with silicates is - strangely regarded by the authors as an argument against the organic - nature of Eozoon. One would think that the extreme frequency of - silicious fillings of the cavities of fossils, and even of silicious - replacement of their tissues, should have prevented the use of such - an argument, without taking into account the opposite conclusions to - be drawn from the various kinds of silicates found in the specimens, - and from the modern filling of Foraminifera by hydrous silicates, as - shown by Ehrenberg, Mantell, Carpenter, Bailey, and Pourtales.[AT] - Further, I have elsewhere shown that the loganite is proved by its - texture to have been a fragmental substance, or at least filled - with loose _debris_; that the Tudor specimens have the cavities - filled with a sedimentary limestone, and that several fragmental - specimens from Madoc are actually wholly calcareous. It is to be - observed, however, that the wholly calcareous specimens present - great difficulties to an observer; and I have no doubt that they are - usually overlooked by collectors in consequence of their not being - developed by weathering, or showing any obvious structure in fresh - fractures. - -[Footnote AT: _Quarterly Journal Geol. Society_, 1864.] - - 3. With regard to the canal system, the authors persist in - confusing the casts of it which occur in serpentine with "metaxite" - concretions, and in likening them to dendritic crystallizations of - silver, etc., and coralloidal forms of carbonate of lime. In answer - to this, I think it quite sufficient to say that I fail to perceive - the resemblance as other than very imperfectly imitative. I may add, - that the case is one of the occurrence of a canal structure in forms - which on other grounds appear to be organic, while the concretionary - forms referred to are produced under diverse conditions, none of - them similar to those of which evidence appears in the specimens of - Eozoon. With the singular theory of pseudomorphism, by means of which - the authors now supplement their previous objections, I leave Dr. - Hunt to deal. - - 4. With respect to the proper wall and its minute tubulation, the - essential error of the authors consists in confounding it with - fibrous and acicular crystals, and in maintaining that because the - tubuli are sometimes apparently confused and confluent they must - be inorganic. With regard to the first of these positions, I may - repeat what I have stated in former papers--that the true cell-wall - presents minute cylindrical processes traversing carbonate of lime, - and usually nearly parallel to each other, and often slightly - bulbose at the extremity. Fibrous serpentine, on the other hand, - appears as angular crystals, closely packed together, while the - numerous spicular crystals of silicious minerals which often appear - in metamorphic limestones, and may be developed by decalcification, - appear as sharp angular needles usually radiating from centres or - irregularly disposed. Their own plate (Ophite from Skye, King and - Rowney's Paper, _Proc. R. I. A._, vol. x.), is an eminent example - of this; and whatever the nature of the crystals represented, they - have no appearance of being true tubuli of Eozoon. I have very often - shown microscopists and geologists the cell-wall along with veins of - chrysotile and coatings of acicular crystals occurring in the same or - similar limestones, and they have never failed at once to recognise - the difference, especially under high powers. - - I do not deny that the tubulation is often imperfectly preserved, - and that in such cases the casts of the tubuli may appear to be - glued together by concretions of mineral matter, or to be broken - or imperfect. But this occurs in all fossils, and is familiar to - any microscopist examining them. How difficult is it in many cases - to detect the minute structure of Nummulites and other fossil - Foraminifera? How often does a specimen of fossil wood present in one - part distorted and confused fibres or mere crystals, with the remains - of the wood forming phragmata between them, when in other parts it - may show the most minute structures in perfect preservation? But - who would use the disintegrated portions to invalidate the evidence - of the parts better preserved? Yet this is precisely the argument - of Professors King and Rowney, and which they have not hesitated - in using in the case of a fossil so old as Eozoon, and so often - compressed, crushed, and partly destroyed by mineralization. - - I have in the above remarks confined myself to what I regard as - absolutely essential by way of explanation and defence of the - organic nature of Eozoon. It would be unprofitable to enter into the - multitude of subordinate points raised by the authors, and their - theory of mineral pseudomorphism is discussed by my friend Dr. Hunt; - but I must say here that this theory ought, in my opinion, to afford - to any chemist a strong presumption against the validity of their - objections, especially since it confessedly does not account for all - the facts, while requiring a most complicated series of unproved and - improbable suppositions. - - The only other new features in the communication to which this note - refers are contained in the "supplementary note." The first of - these relates to the grains of coccolite in the limestone of Aker, - in Sweden. Whether or not these are organic, they are apparently - different from _Eozoon Canadense_. They, no doubt, resemble the - grains referred to by Gümbel as possibly organic, and also similar - granular objects with projections which, in a previous paper, I have - described from Laurentian limestones in Canada. These objects are of - doubtful nature; but if organic, they are distinct from Eozoon. The - second relates to the supposed crystals of malacolite from the same - place. Admitting the interpretation given of these to be correct, - they are no more related to Eozoon than are the curious vermicular - crystals of a micaceous mineral which I have noticed in the Canadian - limestones. - - The third and still more remarkable case is that of a spinel from - Amity, New York, containing calcite in its crevices, including a - perfect canal system preserved in malacolite. With reference to - this, as spinels of large size occur in veins in the Laurentian - rocks, I am not prepared to say that it is absolutely impossible that - fragments of limestone containing Eozoon may not be occasionally - associated with them in their matrix. I confess, however, that - until I can examine such specimens, which I have not yet met with, - I cannot, after my experience of the tendencies of Messrs. Rowney - and King to confound other forms with those of Eozoon, accept their - determinations in a matter so critical and in a case so unlikely.[AU] - -[Footnote AU: I have since ascertained that Laurentian limestone found -at Amity, New York, and containing spinels, does hold fragments of the -intermediate skeleton of Eozoon. The limestone may have been originally -a mass of fragments of this kind with the aluminous and magnesian -material of the spinel in their interstices.] - - If all specimens of Eozoon were of the acervuline character, the - comparison of the chamber-casts with concretionary granules might - have some plausibility. But it is to be observed that the laminated - arrangement is the typical one; and the study of the larger - specimens, cut under the direction of Sir W. E. Logan, shows that - these laminated forms must have grown on certain strata-planes before - the deposition of the overlying beds, and that the beds are, in part, - composed of the broken fragments of similar laminated structures. - Further, much of the apparently acervuline Eozoon rock is composed - of such broken fragments, the interstices between which should not - be confounded with the chambers: while the fact that the serpentine - fills such interstices as well as the chambers shows that its - arrangement is not concretionary. Again, these chambers are filled in - different specimens with serpentine, pyroxene, loganite, calcareous - spar, chondrodite, or even with arenaceous limestone. It is also to - be observed that the examination of a number of limestones, other - than Canadian, by Messrs. King and Rowney, has obliged them to admit - that the laminated forms in combination with the canal-system are - "essentially Canadian," and that the only instances of structures - clearly resembling the Canadian specimens are afforded by limestones - Laurentian in age, and in some of which (as, for instance, in those - of Bavaria and Scandinavia) Carpenter and Gümbel have actually found - the structure of Eozoon. The other serpentine-limestones examined - (for example, that of Skye) are admitted to fail in essential points - of structure; and the only serpentine believed to be of eruptive - origin examined by them is confessedly destitute of all semblance - of Eozoon. Similar results have been attained by the more careful - researches of Prof. Gümbel, whose paper is well deserving of study by - all who have any doubts on this subject. - - -(B.) Reply by Dr. Hunt to Chemical Objections--(_Ibid._). - - "In the _Proceedings of the Royal Irish Academy_, for July 12, - 1869, Messrs. King and Rowney have given us at length their latest - corrected views on various questions connected with Eozoon Canadense. - Leaving to my friend, Dr. Dawson, the discussion of the zoological - aspects of the question, I cannot forbear making a few criticisms - on the chemical and mineralogical views of the authors. The problem - which they had before them was to explain the occurrence of certain - forms which, to skilled observers, like Carpenter, Dawson, and - Rupert Jones, appear to possess all the structural character of the - calcareous skeleton of a foraminiferal organism, and moreover to - show how it happens that these forms of crystalline carbonate of - lime are associated with serpentine in such a way as to lead these - observers to conclude that this hydrous silicate of magnesia filled - and enveloped the calcareous skeleton, replacing the perishable - sarcode. The hypothesis now put forward by Messrs. King and Rowney - to explain the appearances in question, is, that all this curiously - arranged serpentine, which appears to be a cast of the interior of a - complex foraminiferal organism, has been shaped or sculptured out of - plates, prisms, and other solids of serpentine, by "the erosion and - incomplete waste of the latter, _the definite shapes_ being residual - portions of the solid that have not completely disappeared." The - calcite which limits these definite shapes, or, in other words, what - is regarded as the calcareous skeleton of Eozoon, is a 'replacement - pseudomorph' of calcite taking the place of the wasted and eroded - serpentine. It was not a calcareous fossil, filled and surrounded - by the serpentine, but was formed in the midst of the serpentine - itself, by a mysterious agency which dissolved away this mineral to - form a mould, in which the calcite was cast. This marvellous process - can only be paralleled by the operations of that plastic force in - virtue of which sea-shells were supposed by some old naturalists - to be generated in the midst of rocky strata. Such equivocally - formed fossils, whether oysters or Foraminifers, may well be termed - _pseudomorphs_, but we are at a loss to see with what propriety the - authors of this singular hypothesis invoke the doctrines of mineral - pseudomorphism, as taught by Rose, Blum, Bischof, and Dana. In - replacement pseudomorphs, as understood by these authors, a mineral - species disappears and is replaced by another which retains the - external form of the first. Could it be shown that the calcite of the - cell-wall of Eozoon was once serpentine, this portion of carbonate - of lime would be a replacement pseudomorph after serpentine; but why - the portions of this mineral, which on the hypothesis of Messrs. King - and Rowney have been thus replaced, should assume the forms of a - foraminiferal skeleton, is precisely what our authors fail to show, - and, as all must see, is the gist of the whole matter. - - "Messrs. King and Rowney, it will be observed, assume the existence - of calcite as a replacement pseudomorph after serpentine, but give - no evidence of the possibility of such pseudomorphs. Both Rose and - Bischof regard serpentine itself as in all cases, of pseudomorphous - origin, and as the last result of the changes of a number of mineral - species, but give us no example of the pseudomorphous alteration of - serpentine itself. It is, according to Bischof, the very insolubility - and unalterability of serpentine which cause it to appear as the - final result of the change of so many mineral species. Delesse, - moreover, in his carefully prepared table of pseudomorphous minerals, - in which he has resumed the results of his own and all preceding - observers, does not admit the pseudomorphic replacement of serpentine - by calcite, nor indeed by any other species.[AV] If, then, such - pseudomorphs exist, it appears to be a fact hitherto unobserved, - and our authors should at least have given us some evidence of this - remarkable case of pseudomorphism by which they seek to support their - singular hypothesis. - -[Footnote AV: _Annales des Mines_, 5, xvi., 317.] - - "I hasten to say, however, that I reject with Scheerer, Delesse - and Naumann, a great part of the supposed cases of mineral - pseudomorphism, and do not even admit the pseudomorphous origin of - serpentine itself, but believe that this, with many other related - silicates, has been formed by direct chemical precipitation. This - view, which our authors do me the honour to criticise, was set - forth by me in 1860 and 1861,[AW] and will be found noticed more - in detail in the _Geological Report of Canada_, for 1866, p. 229. - I have there and elsewhere maintained that 'steatite, serpentine, - pyroxene, hornblende, and in many cases garnet, epidote, and other - silicated minerals, are formed by a crystallization and molecular - re-arrangement of silicates, generated by chemical processes in - waters at the earth's surface.'[AX] - -[Footnote AW: _Amer. Journ. Science_ (2), xxix., 284; xxxii., 286.] - -[Footnote AX: _Ibid._, xxxvii., 266; xxxviii., 183.] - - "This view, which at once explains the origin of all these bedded - rocks, and the fact that their constituent mineral species, like - silica and carbonate of lime, replace the perishable matter of - organic forms, is designated by Messrs. King and Rowney 'as so - completely destitute of the characters of a scientific hypothesis - as to be wholly unworthy of consideration,' and they speak of my - attempt to maintain this hypothesis as 'a total collapse.' How far - this statement is from the truth my readers shall judge. My views - as to the origin of serpentine and other silicated minerals were - set forth by me as above in 1860-1864, before anything was known - of the mineralogy of Eozoon, and were forced upon me by my studies - of the older crystalline schists of North America. Naumann had - already pointed out the necessity of some such hypothesis when he - protested against the extravagances of the pseudomorphist school, - and maintained that the beds of various silicates found in the - crystalline schists are original deposits, and not formed by an - epigenic process (_Geognosie_, ii., 65, 154, and _Bull. Soc. Geol. - de France_, 2, xviii., 678). This conclusion of Naumann's I have - attempted to explain and support by numerous facts and observations, - which have led me to the hypothesis in question. Gümbel, who accepts - Naumann's view, sustains my hypothesis of the origin of these rocks - in a most emphatic manner,[AY] and Credner, in discussing the genesis - of the Eozoic rocks, has most ably defended it.[AZ] So much for my - theoretical views so contemptuously denounced by Messrs. King and - Rowney, which are nevertheless unhesitatingly adopted by the two - geologists of the time who have made the most special studies of the - rocks in question,--Gümbel in Germany, and Credner in North America. - -[Footnote AY: _Proc. Royal Bavarian Acad._ for 1866, translated in -_Can. Naturalist_, iii., 81.] - -[Footnote AZ: _Die Gliederung der Eozoischen Formations gruppe -Nord.-Amerikas,--a Thesis defended before the University of Leipzig, -March 15, 1869_, by Dr. Hermann Credner. Halle, 1869, p. 53.] - - "It would be a thankless task to follow Messrs. King and Rowney - through their long paper, which abounds in statements as unsound as - those I have just exposed, but I cannot conclude without calling - attention to one misconception of theirs as to my view of the origin - of limestones. They quote Professor Hull's remark to the effect that - the researches of the Canadian geologists and others have shown that - the oldest known limestones of the world owe their origin to Eozoon, - and remark that the existence of great limestone beds in the Eozoic - rocks seems to have influenced Lyell, Ramsay, and others in admitting - the received view of Eozoon. Were there no other conceivable source - of limestones than Eozoon or similar calcareous skeletons, one might - suppose that the presence of such rocks in the Laurentian system - could have thus influenced these distinguished geologists, but - there are found beneath the Eozoon horizon two great formations of - limestone in which this fossil has never been detected. When found, - indeed, it owes its conservation in a readily recognisable form to - the fact, that it was preserved by the introduction of serpentine - at the time of its growth. Above the unbroken Eozoon reefs are - limestones made up apparently of the debris of Eozoon thus preserved - by serpentine, and there is no doubt that this calcareous rhizopod, - growing in water where serpentine was not in process of formation, - might, and probably did, build up pure limestone beds like those - formed in later times from the ruins of corals and crinoids. Nor - is there anything inconsistent in this with the assertion which - Messrs. King and Rowney quote from me, viz., that the popular notion - that _all limestone formations_ owe their origin to organic life is - based upon a fallacy. The idea that marine organisms originate the - carbonate of lime of their skeletons, in a manner somewhat similar to - that in which plants generate the organic matter of theirs, appears - to be commonly held among certain geologists. It cannot, however, - be too often repeated that animals only appropriate the carbonate - of lime which is furnished them by chemical reaction. Were there - no animals present to make use of it, the carbonate of lime would - accumulate in natural waters till these became saturated, and would - then be deposited in an insoluble form; and although thousands of - feet of limestone have been formed from the calcareous skeletons - of marine animals, it is not less true that great beds of ancient - marble, like many modern travertines and tufas, have been deposited - without the intervention of life, and even in waters from which - living organisms were probably absent. To illustrate this with the - parallel case of silicious deposits, there are great beds made - up of silicious shields of diatoms. These during their lifetime - extracted from the waters the dissolved silica, which, but for their - intervention, might have accumulated till it was at length deposited - in the form of schist or of crystalline quartz. In either case the - function of the coral, the rhizopod, or the diatom is limited to - assimilating the carbonate of lime or the silica from its solution, - and the organised form thus given to these substances is purely - accidental. It is characteristic of our authors, that, rather than - admit the limestone beds of the Eozoon rocks to have been formed like - beds of coralline limestone, or deposited as chemical precipitates - like travertine, they prefer, as they assure us, to regard them as - the results of that hitherto unheard-of process, the pseudomorphism - of serpentine; as if the deposition of the carbonate of lime in - the place of dissolved serpentine were a simpler process than its - direct deposition in one or the other of the ways which all the world - understands!" - - -(C.) Dr. Carpenter on the Foraminiferal Relations of Eozoon. - - In the _Annals of Natural History_, for June, 1874, Dr. Carpenter - has given a crushing reply to some objections raised in that journal - by Mr. Carter. He first shows, contrary to the statement of Mr. - Carter, that the fine nummuline tubulation corresponds precisely in - its direction with reference to the chambers, with that observed in - Nummulites and Orbitoides. In the second place, he shows by clear - descriptions and figures, that the relation of the canal system to - the fine tubulation is precisely that which he had demonstrated in - more recent nummuline and rotaline Foraminifera. In the third place - he adduces additional facts to show that in some specimens of Eozoon - the calcareous skeleton has been filled with calcite before the - introduction of any foreign mineral matter. He concludes the argument - in the following words:-- - - "I have thus shown:--(1) that the 'utter incompatibility' asserted - by my opponents to exist between the arrangement of the supposed - 'nummuline tubulation' of Eozoon and true Nummuline structure, so far - from having any real existence, really furnishes an additional point - of conformity; and (2) that three most striking and complete points - of conformity exist between the structure of the best-preserved - specimens of Eozoon, and that of the Nummulites whose tubulation I - described in 1849, and of the Calcarina whose tubulation and canal - system I described in 1860. - - "That I have not troubled myself to reply to the reiterated arguments - in favour of the doctrine [of mineral origin] advanced by Professors - King and Rowney on the strength of the occurrence of undoubted - results of mineralization in the Canadian Ophite, and of still more - marked evidences of the same action in other Ophites, has been - simply because these arguments appeared to me, as I thought they - must also appear to others, entirely destitute of logical force. - Every scientific palæontologist I have ever been acquainted with has - taken the _best_ preserved specimens, not the _worst_, as the basis - of his reconstructions; and if he should meet with distinct evidence - of characteristic organic structure in even a very small fragment - of a doubtful form, he would consider the organic origin of that - form to be thereby substantiated, whatever might be the evidence of - purely mineral arrangement which the greater part of his specimen - may present,--since he would regard that arrangement as a probable - result of _subsequent_ mineralization, by which the original organic - structure has been more or less obscured. If this is _not_ to be our - rule of interpretation, a large part of the palæontological work - of our time must be thrown aside as worthless. If, for example, - Professors King and Rowney were to begin their study of Nummulites - by the examination of their most mineralized forms, they would deem - themselves justified (according to their canons of interpretation) - in denying the existence of the tubulation and canalization which I - described (in 1849) in the N. lævigata preserved almost unaltered in - the London Clay of Bracklesham Bay. - - "My own notions of Eozoic structure have been formed on the - examination of the Canadian specimens selected by the experienced - discrimination of Sir William Logan, as those in which there was - _least_ appearance of metamorphism; and having found in these what I - regarded as unmistakable evidence of an organic structure conformable - to the foraminiferal type, I cannot regard it as any disproof of - that conformity, either to show that the true Eozoic structure has - been frequently altered by mineral metamorphism, or to adduce the - occurrence of Ophites more or less resembling the Eozoon of the - Canadian Laurentians at various subsequent geological epochs. The - existence of any number or variety of _purely mineral_ Ophites would - not disprove the organic origin of the Canadian Eozoon--unless - it could be shown that some wonderful process of mineralization - is competent to construct not only its multiplied alternating - lamellæ of calcite and serpentine, the dendritic extensions of the - latter into the former, and the 'acicular layer' of decalcified - specimens, but (1) the _pre-existing canalization_ of the calcareous - lamellæ, (2) the _unfilled nummuline tubulation_ of the proper - wall of the chambers, and (3) the peculiar _calcarine_ relation of - the canalization and tubulation, here described and figured from - specimens in the highest state of preservation, showing the _least_ - evidence of any mineral change. - - "On the other hand, Professors King and Rowney began their studies of - Eozoic structure upon the Galway Ophite--a rock which Sir Roderick - Murchison described to me at the time as having been so much 'tumbled - about,' that he was not at all sure of its geological position, and - which exhibits such obvious evidences of mineralization, with such - an entire absence of any vestige of organic structure, that I should - never for a moment have thought of crediting it with an organic - origin, but for the general resemblance of its serpentine-grains - to those of the 'acervuline' portion of the Canadian Eozoon. They - pronounced with the most positive certainty upon the mineral origin - of the Canadian Eozoon, before they had subjected transparent - sections of it to any of that careful comparison with similar - sections of recent Foraminifera, which had been the basis of - Dr. Dawson's original determination, and of my own subsequent - confirmation, of its organic structure. - -[Illustration: - Plate VIII. - - _Eozoon and Chrysotile Veins, etc._ - - Fig. 1.--Portion of two laminæ and intervening serpentine, - with chrysotile vein. (_a._) Proper wall tubulated. (_b._) - Intermediate skeleton, with large canals. (_c._) Openings of - small chamberlets filled with serpentine. (_s._) Serpentine - filling chamber. (_s^1._) Vein of chrysotile, showing its - difference from the proper wall. - - Fig. 2.--Junction of a canal and the proper wall. Lettering as in - Fig. 1. - - Fig. 3.--Proper wall shifted by a fault, and more recent chrysotile - vein not faulted. Lettering as in Fig. 1. - - Fig. 4.--Large and small canals filled with dolomite. - - Fig. 5.--Abnormally thick portion of intermediate skeleton, with - large tubes and small canals filled with dolomite.] - - - - -CHAPTER VIII. - -THE DAWN-ANIMAL AS A TEACHER IN SCIENCE. - - -The thoughts suggested to the philosophical naturalist by the -contemplation of the dawn of life on our planet are necessarily many -and exciting, and the subject has in it the materials for enabling the -general reader better to judge of some of the theories of the origin of -life agitated in our time. In this respect our dawn-animal has scarcely -yet had justice; and we may not be able to render this in these pages. -Let us put it into the witness-box, however, and try to elicit its -testimony as to the beginnings of life. - -Looking down from the elevation of our physiological and mental -superiority, it is difficult to realize the exact conditions in which -life exists in creatures so simple as the Protozoa. There may perhaps -be higher intelligences that find it equally difficult to realize how -life and reason can manifest themselves in such poor houses of clay -as those we inhabit. But placing ourselves near to these creatures, -and entering as it were into sympathy with them, we can understand -something of their powers and feelings. In the first place it is plain -that they can vigorously, if roughly, exercise those mechanical, -chemical, and vegetative powers of life which are characteristic of -the animal. They can seize, swallow, digest, and assimilate food; and, -employing its albuminous parts in nourishing their tissues, can burn -away the rest in processes akin to our respiration, or reject it from -their system. Like us, they can subsist only on food which the plant -has previously produced; for in this world, from the beginning of time, -the plant has been the only organism which could use the solar light -and heat as forces to enable it to turn the dead elements of matter -into living, growing tissues, and into organic compounds capable of -nourishing the animal. Like us, the Protozoa expend the food which -they have assimilated in the production of animal force, and in doing -so cause it to be oxidized, or burnt away, and resolved again into -dead matter. It is true that we have much more complicated apparatus -for performing these functions, but it does not follow that this gives -us much real superiority, except relatively to the more difficult -conditions of our existence. The gourmand who enjoys his dinner may -have no more pleasure in the act than the AmÅ“ba which swallows a -Diatom; and for all that the man knows of the subsequent processes to -which the food is subjected, his interior might be a mass of jelly, -with extemporised vacuoles, like that of his humble fellow-animal. The -workman or the athlete has bones and muscles of vastly complicated -structure, but to him the muscular act is as simple and unconscious a -process as the sending out of a pseudopod to a Protozoon. The clay is -after all the same, and there may be as much credit to the artist in -making a simple organism with varied powers, as a more complex frame -for doing nicer work. It is a weakness of humanity to plume itself on -advantages not of its own making, and to treat its superior gifts as -if they were the result of its own endeavours. The truculent traveller -who illustrated his boast of superiority over the Indian by comparing -his rifle with the bow and arrows of the savage, was well answered by -the question, "Can you make a rifle?" and when he had to answer, "No," -by the rejoinder, "Then I am at least better than you, for I can make -my bow and arrows." The AmÅ“ba or the Eozoon is probably no more than we -its own creator; but if it could produce itself out of vegetable matter -or out of inorganic substances, it might claim in so far a higher -place in the scale of being than we; and as it is, it can assert equal -powers of digestion, assimilation, and motion, with much less of bodily -mechanism. - -In order that we may feel, a complicated apparatus of nerves and -brain-cells has to be constructed and set to work; but the Protozoon, -without any distinct brain, is all brain, and its sensation is simply -direct. Thus vision in these creatures is probably performed in a rough -way by any part of their transparent bodies, and taste and smell are no -doubt in the same case. Whether they have any perception of sound as -distinct from the mere vibrations ascertained by touch, we do not know. -Here also we are not far removed above the Protozoa, especially those -of us to whom touch, seeing, and hearing are mere feelings, without -thought or knowledge of the apparatus employed. We might so far as -well be AmÅ“bas. As we rise higher we meet with more differences. Yet -it is evident that our gelatinous fellow-being can feel pain, dread -danger, desire possessions, enjoy pleasure, and in a simple unconscious -way entertain many of the appetites and passions that affect ourselves. -The wonder is that with so little of organization it can do so much. -Yet, perhaps, life can manifest itself in a broader and more intense -way where there is little organization; and a highly strung and -complex organism is not so much a necessary condition of a higher life -as a mere means of better adapting it to its present surroundings. -Those philosophies which identify the thinking mind with the material -organism, must seem outrageous blunders to an AmÅ“ba on the one hand, or -to an angel on the other, could either be enabled to understand them; -which, however, is not very probable, as they are too intimately bound -up with the mere prejudices incident to the present condition of our -humanity. In any case the Protozoa teach us how much of animal function -may be fulfilled by a very simple organism, and warn us against the -fallacy that creatures of this simple structure are necessarily nearer -to inorganic matter, and more easily developed from it than beings of -more complex mould. - -A similar lesson is taught by the complexity of their skeletons. -We speak in a crude unscientific way of these animals accumulating -calcareous matter, and building up reefs of limestone. We must, -however, bear in mind that they are as dependent on their food for -the materials of their skeletons as we are, and that their crusts -grow in the interior of the sarcode just as our bones do within our -bodies. The provision even for nourishing the interior of the skeleton -by tubuli and canals is in principle similar to that involved in the -Haversian canals, cells, and canalicules of bone. The AmÅ“ba of course -knows neither more nor less of this than the average Englishman. -It is altogether a matter of unconscious growth. The process in -the Protozoa strikes some minds, however, as the more wonderful of -the two. It is, says an eminent modern physiologist, a matter of -"profound significance" that this "particle of jelly [the sarcode -of a Foraminifer] is capable of guiding physical forces in such a -manner as to give rise to these exquisite and almost mathematically -arranged structures." Respecting the structures themselves there is no -exaggeration in this. No arch or dome framed by human skill is more -perfect in beauty or in the realization of mechanical ideas than the -tests of some Foraminifera, and none is so complete and wonderful in -its internal structure. The particle of jelly, however, is a figure of -speech. The body of the humblest Foraminifer is much more than this. -It is an organism with divers parts, as we have already seen in a -previous chapter, and it is endowed with the mysterious forces of life -which in it guide the physical forces, just as they do in building -up phosphate of lime in our bones, or indeed just as the will of the -architect does in building a palace. The profound significance which -this has, reaches beyond the domain of the physical and vital, even to -the spiritual. It clings to all our conceptions of living things: quite -as much, for example, to the evolution of an animal with all its parts -from a one-celled germ, or to the connection of brain-cells with the -manifestations of intelligence. Viewed in this way, we may share with -the author of the sentence I have quoted his feeling of veneration in -the presence of this great wonder of animal life, "burning, and not -consumed," nay, building up, and that in many and beautiful forms. We -may realize it most of all in the presence of the organism which was -perhaps the first to manifest on our planet these marvellous powers. -We must, however, here also, beware of that credulity which makes too -many thinkers limit their conceptions altogether to physical force -in matters of this kind. The merely materialistic physiologist is -really in no better position than the savage who quails before the -thunderstorm, or rejoices in the solar warmth, and seeing no force or -power beyond, fancies himself in the immediate presence of his God. In -Eozoon we must discern not only a mass of jelly, but a being endowed -with that higher vital force which surpasses vegetable life and also -physical and chemical forces; and in this animal energy we must see an -emanation from a Will higher than our own, ruling vitality itself; and -this not merely to the end of constructing the skeleton of a Protozoon, -but of elaborating all the wonderful developments of life that were to -follow in succeeding ages, and with reference to which the production -and growth of this creature were initial steps. It is this mystery of -design which really constitutes the "profound significance" of the -foraminiferal skeleton. - -Another phenomenon of animality forced upon our notice by the Protozoa -is that of the conditions of life in animals not individual, as we -are, but aggregative and cumulative in indefinite masses. What, for -instance, the relations to each other of the Polyps, growing together -in a coral mass, of the separate parts of a Sponge, or the separate -cells of a Foraminifer, or of the sarcode mass of an indefinitely -spread out Stromatopora or Bathybius. In the case of the Polyps, we -may believe that there is special sensation in the tentacles and -oral opening of each individual, and that each may experience hunger -when in want, or satisfaction when it is filled with food, and that -injuries to one part of the mass may indirectly affect other parts, -but that the nutrition of the whole mass may be as much unfelt by the -individual Polyps as the processes going on in our own bones are by -us. So in the case of a large Sponge or Foraminifer, there may be some -special sensation in individual cells, pseudopods, or segments, and -the general sensation may be very limited, while unconscious living -powers pervade the whole. In this matter of aggregation of animals we -have thus various grades. The Foraminifers and Sponges present us with -the simplest of all, and that which most resembles the aggregation of -buds in the plant. The Polyps and complex Bryozoons present a higher -and more specialised type; and though the bilateral symmetry which -obtains in the higher animals is of a different nature, it still at -least reminds us of that multiplication of similar parts which we see -in the lower grades of being. It is worthy of notice here that the -lower animals which show aggregative tendencies present but imperfect -indications, or none at all, of bilateral symmetry. Their bodies, like -those of plants, are for the most part built up around a central axis, -or they show tendencies to spiral modes of growth. - -It is this composite sort of life which is connected with the main -geological function of the Foraminifer. While active sensation, -appetite, and enjoyment pervade the pseudopods and external sarcode -of the mass, the hard skeleton common to the whole is growing within; -and in this way the calcareous matter is gradually removed from -the sea water, and built up in solid reefs, or in piles of loose -foraminiferal shells. Thus it is the aggregative or common life, -alike in Foraminifers as in Corals, that tends most powerfully to the -accumulation of calcareous matter; and those creatures whose life is -of this complex character are best suited to be world-builders, since -the result of their growth is not merely a cemetery of their osseous -remains, but a huge communistic edifice, to which multitudes of lives -have contributed, and in which successive generations take up their -abode on the remains of their ancestors. This process, so potent in -the progress of the earth's geological history, began, as far as we -know, with Eozoon. - -Whether, then, in questioning our proto-foraminifer, we have reference -to the vital functions of its gelatinous sarcode, to the complexity and -beauty of its calcareous test, or to its capacity for effecting great -material results through the union of individuals, we perceive that we -have to do, not with a low condition of those powers which we designate -life, but with the manifestation of those powers through the means of a -simple organism; and this in a degree of perfection which we, from our -point of view, would have in the first instance supposed impossible. - -If we imagine a world altogether destitute of life, we still might -have geological formations in progress. Not only would volcanoes belch -forth their liquid lavas and their stones and ashes, but the waves and -currents of the ocean and the rains and streams on the land, with the -ceaseless decomposing action of the carbonic acid of the atmosphere, -would be piling up mud, sand, and pebbles in the sea. There might even -be some formation of limestone taking place where springs charged -with bicarbonate of lime were oozing out on the land or the bottom of -the waters. But in such a world all the carbon would be in the state -of carbonic acid, and all the limestone would either be diffused in -small quantities through various rocks or in limited local beds, or -in solution, perhaps as chloride of calcium, in the sea. Dr. Hunt has -given chemical grounds for supposing that the most ancient seas were -largely supplied with this very soluble salt, instead of the chloride -of sodium, or common salt, which now prevails in the sea-water. - -Where in such a world would life be introduced? on the land or in the -waters? All scientific probability would say in the latter. The ocean -is now vastly more populous than the land. The waters alone afford -the conditions necessary at once for the most minute and the grandest -organisms, at once for the simplest and for others of the most complex -character. Especially do they afford the best conditions for those -animals which subsist in complex communities, and which aggregate large -quantities of mineral matter in their skeletons. So true is this that -up to the present time all the species of Protozoa and of the animals -most nearly allied to them are aquatic. Even in the waters, however, -plant life, though possibly in very simple forms, must precede the -animal. - -Let humble plants, then, be introduced in the waters, and they would -at once begin to use the solar light for the purpose of decomposing -carbonic acid, and forming carbon compounds which had not before -existed, and which independently of vegetable life would never have -existed. At the same time lime and other mineral substances present in -the sea-water would be fixed in the tissues of these plants, either in -a minute state of division, as little grains or Coccoliths, or in more -solid masses like those of the Corallines and Nullipores. In this way -a beginning of limestone formation might be made, and quantities of -carbonaceous and bituminous matter, resulting from the decay of marine -plants might accumulate in the sea-bottom. Now arises the opportunity -for animal life. The plants have collected stores of organic matter, -and their minute germs, along with microscopic species, are floating -everywhere in the sea. Nay, there may be abundant examples of those -AmÅ“ba-like germs of aquatic plants, simulating for a time the life -of the animal, and then returning into the circle of vegetable life. -In these some might see precursors of the Protozoa, though they are -probably rather prophetic analogues than blood relations. The plant -has fulfilled its function as far as the waters are concerned, and now -arises the opportunity for the animal. In what form shall it appear? -Many of its higher forms, those which depend upon animal food or on the -more complex plants for subsistence, would obviously be unsuitable. -Further, the sea-water is still too much saturated with saline matter -to be fit for the higher animals of the waters. Still further, there -may be a residue of internal heat forbidding coolness, and that -solution of free oxygen which is an essential condition of existence to -most of the modern animals. Something must be found suitable for this -saline, imperfectly oxygenated, tepid sea. Something too is wanted that -can aid in introducing conditions more favourable to higher life in -the future. Our experience of the modern world shows us that all these -conditions can be better fulfilled by the Protozoa than by any other -creatures. They can live now equally in those great depths of ocean -where the conditions are most unfavourable to other forms of life, and -in tepid unhealthy pools overstocked with vegetable matter in a state -of putridity. They form a most suitable basis for higher forms of life. -They have remarkable powers of removing mineral matters from the waters -and of fixing them in solid forms. So in the fitness of things Eozoon -is just what we need, and after it has spread itself over the mud and -rock of the primeval seas, and built up extensive reefs therein, other -animals may be introduced capable of feeding on it, or of sheltering -themselves in its stony masses, and thus we have the appropriate dawn -of animal life. - -But what are we to say of the cause of this new series of facts, so -wonderfully superimposed upon the merely vegetable and mineral? Must -it remain to us as an act of creation, or was it derived from some -pre-existing matter in which it had been potentially present? Science -fails to inform us, but conjectural "phylogeny" steps in and takes its -place. Haeckel, the prophet of this new philosophy, waves his magic -wand, and simple masses of sarcode spring from inorganic matter, and -form diffused sheets of sea-slime, from which are in time separated -distinct AmÅ“boid and Foraminiferal forms. Experience, however, gives us -no facts whereon to build this supposition, and it remains neither more -nor less scientific or certain than that old fancy of the Egyptians, -which derived animals from the fertile mud of the Nile. - -If we fail to learn anything of the origin of Eozoon, and if its -life-processes are just as inscrutable as those of higher creatures, -we can at least inquire as to its history in geological time. In this -respect we find in the first place that the Protozoa have not had -a monopoly in their profession of accumulators of calcareous rock. -Originated by Eozoon in the old Laurentian time, this process has -been proceeding throughout the geological ages; and while Protozoa, -equally simple with the great prototype of the race, have been and -are continuing its function, and producing new limestones in every -geological period, and so adding to the volume of the successive -formations, new workers of higher grades have been introduced, capable -of enjoying higher forms of animal activity, and equally of labouring -at the great task of continent-building; of existing, too, in seas -less rich in mineral substances than those of the Eozoic time, and for -that very reason better suited to higher and more skilled artists. It -is to be observed in connection with this, that as the work of the -Foraminifers has thus been assumed by others, their size and importance -have diminished, and the grander forms of more recent times have some -of them been fain to build up their hard parts of cemented sand instead -of limestone. - -But we further find that, while the first though not the only organic -gatherers of limestone from the ocean waters, they have had to do, not -merely with the formation of calcareous sediments, but also with that -of silicious deposits. The greenish silicate called glauconite, or -green-sand, is found to be associated with much of the foraminiferal -slime now accumulating in the ocean, and also with the older deposits -of this kind now consolidated in chalks and similar rocks. This name -glauconite is, as Dr. Hunt has shown, employed to designate not only -the hydrous silicate of iron and potash, which perhaps has the best -right to it, but also compounds which contain in addition large -percentages of alumina, or magnesia, or both; and one glauconite from -the Tertiary limestones near Paris, is said to be a true serpentine, -or hydrous silicate of magnesia.[BA] Now the association of such -substances with Foraminifera is not purely accidental. Just as a -fragment of decaying wood, imbedded in sediment, has the power of -decomposing soluble silicates carried to it by water, and parting with -its carbon in the form of carbonic acid, in exchange for the silica, -and thus replacing, particle by particle, the carbon of the wood -with silicon, so that at length it becomes petrified into a flinty -mass, so the sarcode of a Foraminifer, which is a more dense kind of -animal matter than is usually supposed, can in like manner abstract -silica from the surrounding water or water-soaked sediment. From some -peculiarity in the conditions of the case, however, our Protozoon -usually becomes petrified with a hydrous silicate instead of with pure -silica. The favourable conditions presented by the deep sea for the -combination of silica with bases, may perhaps account in part for -this. But whatever the cause, it is usual to find fossil Foraminifera -with their sarcode replaced by such material. We also find beds of -glauconite retaining the forms of Foraminifera, while the calcareous -tests of these have been removed, apparently by acid waters. - -[Footnote BA: Berthier, quoted by Hunt.] - -One consideration which, though conjectural, deserves notice, is -connected with the food of these humble animals. They are known to feed -to a large extent on minute plants, the Diatoms, and other organisms -having silica in their skeletons or cell-walls, and consequently -soluble silicates in their juices. The silicious matter contained -in these organisms is not wanted by the Foraminifera for their own -skeletons, and will therefore be voided by them as an excrementitious -matter. In this way, where Foraminifera greatly abound, there may be a -large production of soluble silica and silicates, in a condition ready -to enter into new and insoluble compounds, and to fill the cavities -and pores of dead shells. Thus glauconite and even serpentine may, -in a certain sense, be a sort of foraminiferal coprolitic matter or -excrement. Of course it is not necessary to suppose that this is the -only source of such materials. They may be formed in other ways; but I -suggest this as at least a possible link of connection. - -Whether or not the conjecture last mentioned has any validity, there -is another and most curious bond of connection between oceanic -Protozoa and silicious deposits. Professor Wyville Thompson reports -from the _Challenger_ soundings, that in certain areas of the South -Pacific the ordinary foraminiferal ooze is replaced by a peculiar red -clay, which he attributes to the action of water laden with carbonic -acid, in removing all the lime, and leaving this red mud as a sort -of ash, composed of silica, alumina, and iron oxide. Now this is in -all probability a product of the decomposition and oxidation of the -glauconitic matter contained in the ooze. Thus we learn that when areas -on which calcareous deposits have been accumulated by Protozoa, are -invaded by cold arctic or antarctic waters charged with carbonic acid, -the carbonate of lime may be removed, and the glauconite left, or even -the latter may be decomposed, leaving silicious, aluminous, and other -deposits, which may be quite destitute of any organic structures, or -retain only such remnants of them as have been accidentally or by -their more resisting character protected from destruction.[BB] In this -way it may be possible that many silicious rocks of the Laurentian -and Primordial ages, which now show no trace of organization, may be -indirectly products of the action of life. When the recent deposits -discovered by the _Challenger_ dredgings shall have been more fully -examined, we may perhaps have the means of distinguishing such rocks, -and thus of still further enlarging our conceptions of the part played -by Protozoa in the drama of the earth's history. In any case it seems -plain that beds of green-sand and similar hydrous silicates may be the -residue of thick deposits of foraminiferal limestone or chalky matter, -and that these silicates may in their turn be oxidised and decomposed, -leaving beds of apparently inorganic clay. Such beds may finally be -consolidated and rendered crystalline by metamorphism, and thus a -great variety of silicated rocks may result, retaining little or no -indication of any connection with the agency of life. We can scarcely -yet conjecture the amount of light which these new facts may eventually -throw on the serpentine and other rocks of the Eozoic age. In the -meantime they open up a noble field to chemists and microscopists. - -[Footnote BB: The "red chalk" of Antrim, and that of Speeton, contain -arenaceous Foraminifera and silicious casts of their shells, apparently -different from typical glauconite, and the extremely fine ferruginous -and argillaceous sediment of these chalks may well be decomposed -glauconitic matter like that of the South Pacific. I have found these -beds, the hard limestones of the French Neocomian, and the altered -green-sands of the Alps, very instructive for comparison with the -Laurentian limestones; and they well deserve study by all interested in -such subjects.] - -When the marvellous results of recent deep-sea dredgings were first -made known, and it was found that chalky foraminiferal earth is yet -accumulating in the Atlantic, with sponges and sea urchins resembling -in many respects those whose remains exist in the chalk, the fact was -expressed by the statement that we still live in the chalk period. Thus -stated the conclusion is scarcely correct. We do not live in the chalk -period, but the conditions of the chalk period still exist in the -deep sea. We may say more than this. To some extent the conditions of -the Laurentian period still exist in the sea, except in so far as they -have been removed by the action of the Foraminifera and other limestone -builders. To those who can realize the enormous lapse of time involved -in the geological history of the earth, this conveys an impression -almost of eternity in the existence of this oldest of all the families -of the animal kingdom. - -We are still more deeply impressed with this when we bring into view -the great physical changes which have occurred since the dawn of life. -When we consider that the skeletons of Eozoon contribute to form the -oldest hills of our continents; that they have been sealed up in solid -marble, and that they are associated with hard crystalline rocks -contorted in the most fantastic manner; that these rocks have almost -from the beginning of geological time been undergoing waste to supply -the material of new formations; that they have witnessed innumerable -subsidences and elevations of the continents; and that the greatest -mountain chains of the earth have been built up from the sea since -Eozoon began to exist,--we acquire a most profound impression of the -persistence of the lower forms of animal life, and know that mountains -may be removed and continents swept away and replaced, before the least -of the humble gelatinous Protozoa can finally perish. Life may be a -fleeting thing in the individual, but as handed down through successive -generations of beings, and as a constant animating power in successive -organisms, it appears, like its Creator, eternal. - -This leads to another and very serious question. How long did lineal -descendants of Eozoon exist, and do they still exist? We may for the -present consider this question apart from ideas of derivation and -elevation into higher planes of existence. Eozoon as a species and -even as a genus may cease to exist with the Eozoic age, and we have no -evidence whatever that Archæocyathus, Stromatopora, or Receptaculites -are its modified descendants. As far as their structures inform us, -they may as much claim to be original creations as Eozoon itself. -Still descendants of Eozoon may have continued to exist, though we -have not yet met with them. I should not be surprised to hear of a -veritable specimen being some day dredged alive in the Atlantic or -the Pacific. It is also to be observed that in animals so simple as -Eozoon many varieties may appear, widely different from the original. -In these the general form and habit of life are the most likely things -to change, the minute structures much less so. We need not, therefore, -be surprised to find its descendants diminishing in size or altering -in general form, while the characters of the fine tubulation and of -the canal system would remain. We need not wonder if any sessile -Foraminifer of the Nummuline group should prove to be a descendant -of Eozoon. It would be less likely that a Sponge or a Foraminifer of -the Rotaline type should originate from it. If one could only secure -a succession of deep-sea limestones with Foraminifers, extending all -the way from the Laurentian to the present time, I can imagine nothing -more interesting than to compare the whole series, with the view of -ascertaining the limits of descent with variation, and the points where -new forms are introduced. We have not yet such a series, but it may be -obtained; and as Foraminifera are eminently cosmopolitan, occurring -over vastly wide areas of sea-bottom, and are very variable, they would -afford a better test of theories of derivation than any that can be -obtained from the more locally distributed and less variable animals -of higher grade. I was much struck with this recently, in examining a -series of Foraminifera from the Cretaceous of Manitoba, and comparing -them with the varietal forms of the same species in the interior of -Nebraska, 500 miles to the south, and with those of the English chalk -and of the modern seas. In all these different times and places we had -the same species. In all they existed under so many varietal forms -passing into each other, that in former times every species had been -multiplied into several. Yet in all, the identical varietal forms -were repeated with the most minute markings alike. Here were at once -constancy the most remarkable and variations the most extensive. If we -dwell on the one to the exclusion of the other, we reach only one-sided -conclusions, imperfect and unsatisfactory. By taking both in connection -we can alone realize the full significance of the facts. We cannot -yet obtain such series for all geological time; but it may even now -be worth while to inquire, What do we know as to any modification in -the case of the primeval Foraminifers, whether with reference to the -derivation from them of other Protozoa or of higher forms of life? - -There is no link whatever in geological fact to connect Eozoon with any -of the Mollusks, Radiates, or Crustaceans of the succeeding Primordial. -What may be discovered in the future we cannot conjecture; but at -present these stand before us as distinct creations. It would of course -be more probable that Eozoon should be the ancestor of some of the -Foraminifera of the Primordial age, but strangely enough it is very -dissimilar from all these except Stromatopora; and here, as already -stated, the evidence of minute structure fails to a great extent, and -Eozoon Bavaricum of the Huronian age scarcely helps to bridge over the -gap which yawns in our imperfect geological record. Of actual facts, -therefore, we have none; and those evolutionists who have regarded the -dawn-animal as an evidence in their favour, have been obliged to have -recourse to supposition and assumption. - -Taking the ground of the derivationist, it is convenient to assume -(1) that Eozoon was either the first or nearly the first of animals, -and that, being a Protozoan of simple structure, it constitutes an -appropriate beginning of life; (2) that it originated from some -unexplained change in the protoplasmic or albuminous matter of some -humble plant, or directly from inorganic matter, or at least was -descended from some creature only a little more simple which had -being in this way; (3) that it had in itself unlimited capacities -for variation and also for extension in time; (4) that it tended to -multiply rapidly, and at last so to occupy the ocean that a struggle -for existence arose; (5) that though at first, from the very nature -of its origin, adapted to the conditions of the world, yet as these -conditions became altered by physical changes, it was induced to -accommodate itself to them, and so to pass into new species and genera, -until at last it appeared in entirely new types in the Primordial fauna. - -These assumptions are, with the exception of the first two, merely -the application to Eozoon of what have been called the Darwinian laws -of multiplication, of limited population, of variation, of change of -physical conditions, and of equilibrium of nature. If otherwise proved, -and shown to be applicable to creatures like Eozoon, of course we must -apply them to it; but in so far as that creature itself is concerned -they are incapable of proof, and some of them contrary to such evidence -as we have. We have, for example, no connecting link between Eozoon and -any form of vegetable life. Its structures are such as to enable us at -once to assign it to the animal kingdom, and if we seek for connecting -links between the lower animals and plants we have to look for them -in the modern waters. We have no reason to conclude that Eozoon could -multiply so rapidly as to fill all the stations suitable for it, and to -commence a struggle for existence. On the contrary, after the lapse of -untold ages the conditions for the life of Foraminifers still exist -over two-thirds of the surface of the earth. In regard to variation, we -have, it is true, evidence of the wide range of varieties of species -in Protozoa, within the limits of the group, but none whatever of any -tendency to pass into other groups. Nor can it be proved that the -conditions of the ocean were so different in Cambrian or Silurian times -as to preclude the continued and comfortable existence of Eozoon. -New creatures came in which superseded it, and new conditions more -favourable in proportion to these new creatures, but neither the new -creatures nor the new conditions were necessarily or probably connected -with Eozoon, any farther than that it may have served newer tribes of -animals for food, and may have rid the sea of some of its superfluous -lime in their interest. In short, the hypothesis of evolution will -explain the derivation of other animals from Eozoon if we adopt its -assumptions, just as it will in that case explain anything else, but -the assumptions are improbable, and contrary to such facts as we know. - -Eozoon itself, however, bears some negative though damaging testimony -against evolution, and its argument may be thus stated in what we may -imagine to be its own expressions:--"I, Eozoon Canadense, being a -creature of low organization and intelligence, and of practical turn, -am no theorist, but have a lively appreciation of such facts as I am -able to perceive. I found myself growing upon the sea-bottom, and know -not whence I came. I grew and flourished for ages, and found no let or -hindrance to my expansion, and abundance of food was always floated -to me without my having to go in search of it. At length a change -came. Certain creatures with hard snouts and jaws began to prey on -me. Whence they came I know not; I cannot think that they came from -the germs which I had dispersed so abundantly throughout the ocean. -Unfortunately, just at the same time lime became a little less abundant -in the waters, perhaps because of the great demands I myself had made, -and thus it was not so easy as before to produce a thick supplemental -skeleton for defence. So I had to give way. I have done my best to -avoid extinction; but it is clear that I must at length be overcome, -and must either disappear or subside into a humbler condition, and that -other creatures better provided for the new conditions of the world -must take my place." In such terms we may suppose that this patriarch -of the seas might tell his history, and mourn his destiny, though he -might also congratulate himself on having in an honest way done his -duty and fulfilled his function in the world, leaving it to other and -perhaps wiser creatures to dispute as to his origin and fate, while -much less perfectly fulfilling the ends of their own existence. - -Thus our dawn-animal has positively no story to tell as to his own -introduction or his transmutation into other forms of existence. -He leaves the mystery of creation where it was; but in connection -with the subsequent history of life we can learn from him a little -as to the laws which have governed the succession of animals in -geological time. First, we may learn that the plan of creation has been -progressive, that there has been an advance from the few, low, and -generalized types of the primæval ocean to the more numerous, higher, -and more specialized types of more recent times. Secondly, we learn -that the lower types, when first introduced, and before they were -subordinated to higher forms of life, existed in some of their grandest -modifications as to form and complexity, and that in succeeding ages, -when higher types were replacing them, they were subjected to decay and -degeneracy. Thirdly, we learn that while the species has a limited term -of existence in geological time, any grand type of animal existence, -like that of the Foraminifera or Sponges, for example, once introduced, -continues and finds throughout all the vicissitudes of the earth some -appropriate residence. Fourthly, as to the mode of introduction of new -types, or whether such creatures as Eozoon had any direct connection -with the subsequent introduction of mollusks, worms, or crustaceans, it -is altogether silent, nor can it predict anything as to the order or -manner of their introduction. - -Had we been permitted to visit the Laurentian seas, and to study Eozoon -and its contemporary Protozoa when alive, it is plain that we could not -have foreseen or predicted from the consideration of such organisms -the future development of life. No amount of study of the prototypal -Foraminifer could have led us distinctly to the conception of even -a Sponge or a Polyp, much less of any of the higher animals. Why is -this? The answer is that the improvement into such higher types does -not take place by any change of the elementary sarcode, either in those -chemical, mechanical, or vital properties which we can study, but in -the adding to it of new structures. In the Sponge, which is perhaps -the nearest type of all, we have the movable pulsating cilium and true -animal cellular tissue, and along with this the spicular or fibrous -skeleton, these structures leading to an entire change in the mode of -life and subsistence. In the higher types of animals it is the same. -Even in the highest we have white blood-corpuscles and germinal matter, -which, in so far as we know, carry on no higher forms of life than -those of an AmÅ“ba; but they are now made subordinate to other kinds of -tissue, of great variety and complexity, which never have been observed -to arise out of the growth of any Protozoon. There would be only a very -few conceivable inferences which the highest finite intelligence could -deduce as to the development of future and higher animals. He might -infer that the foraminiferal sarcode, once introduced, might be the -substratum or foundation of other but unknown tissues in the higher -animals, and that the Protozoan type might continue to subsist side -by side with higher forms of living things as they were successively -introduced. He might also infer that the elevation of the animal -kingdom would take place with reference to those new properties of -sensation and voluntary motion in which the humblest animals diverge -from the life of the plant. - -It is important that these points should be clearly before our minds, -because there has been current of late among naturalists a loose way -of writing with reference to them, which seems to have imposed on many -who are not naturalists. It has been said, for example, that such an -organism as Eozoon may include potentially all the structures and -functions of the higher animals, and that it is possible that we might -be able to infer or calculate all these with as much certainty as we -can calculate an eclipse or any other physical phenomenon. Now, there -is not only no foundation in fact for these assertions, but it is from -our present standpoint not conceivable that they can ever be realized. -The laws of inorganic matter give no data whence any _à priori_ -deductions or calculations could be made as to the structure and -vital forces of the plant. The plant gives no data from which we can -calculate the functions of the animal. The Protozoon gives no data from -which we can calculate the specialties of the Mollusc, the Articulate, -or the Vertebrate. Nor unhappily do the present conditions of life of -themselves give us any sure grounds for predicting the new creations -that may be in store for our old planet. Those who think to build a -philosophy and even a religion on such data are mere dreamers, and have -no scientific basis for their dogmas. They are more blind guides than -our primæval Protozoon himself would be, in matters whose real solution -lies in the harmony of our own higher and immaterial nature with the -Being who is the author of all life--the Father "from whom every -family in heaven and earth is named." - -While this work was going through the press, Lyell, the greatest -geological thinker of our time, passed away. In the preceding pages I -have refrained from quoting the many able geologists and biologists who -have publicly accepted the evidence of the animal nature of Eozoon as -sufficient, preferring to rest my case on its own merits rather than on -authority; but it is due to the great man whose loss we now mourn, to -say that, before the discovery of Eozoon, he had expressed on general -grounds his anticipation that fossils would be found in the rocks older -than the so-called Primordial Series, and that he at once admitted the -organic nature of Eozoon, and introduced it, as a fossil, into the -edition of his Elements of Geology published in the same year in which -it was described. - - - - -APPENDIX. - -CHARACTERS OF LAURENTIAN AND HURONIAN PROTOZOA. - - -It may be useful to students to state the technical characters of -Eozoon, in addition to the more popular and general descriptions in the -preceding pages. - - -_Genus_ EOZOON. - -Foraminiferal skeletons, with irregular and often confluent cells, -arranged in concentric and horizontal laminæ, or sometimes piled in an -acervuline manner. Septal orifices irregularly disposed. Proper wall -finely tubulated. Intermediate skeleton with branching canals. - - -Eozoon Canadense, _Dawson_. - -In rounded masses or thick encrusting sheets, frequently of large -dimensions. Typical structure stromatoporoid, or with concentric -calcareous walls, frequently uniting with each other, and separating -flat chambers, more or less mammillated, and spreading into horizontal -lobes and small chamberlets; chambers often confluent and crossed by -irregular calcareous pillars connecting the opposite walls. Upper -part often composed of acervuline chambers of rounded forms. Proper -wall tubulated very finely. Intermediate skeleton largely developed, -especially at the lower part, and traversed by large canals, often -with smaller canals in their interstices. Lower laminæ and chambers -often three millimetres in thickness. Upper laminæ and chambers one -millimetre or less. Age Laurentian and perhaps Huronian. - -_Var._ MINOR.--Supplemental skeleton wanting, except near the base, and -with very fine canals. Laminæ of sarcode much mammillated, thin, and -separated by very thin walls. Probably a depauperated variety. - -_Var._ ACERVULINA.--In oval or rounded masses, wholly acervuline. Cells -rounded; intermediate skeleton absent or much reduced; cell-walls -tubulated. This may be a distinct species, but it closely resembles the -acervuline parts of the ordinary form. - - -Eozoon Bavaricum, _Gümbel_. - -Composed of small acervuline chambers, separated by contorted walls, -and associated with broad plate-like chambers below. Large canals -in the thicker parts of the intermediate skeleton. Differs from _E. -Canadense_ in its smaller and more contorted chambers. Age probably -Huronian. - - -_Genus_ ARCHÆOSPHERINA. - -A provisional genus, to include rounded solitary chambers, or -globigerine assemblages of such chambers, with the cell-wall -surrounding them tubulated as in Eozoon. They may be distinct -organisms, or gemmæ or detached fragments of Eozoon. Some of them -much resemble the bodies figured by Dr. Carpenter, as gemmæ or ova -and primitive chambers of Orbitolites. They are very abundant on some -of the strata surfaces of the limestone at Côte St. Pierre. Age Lower -Laurentian. - - -SYSTEMATIC POSITION OF EOZOON. - -The unsettled condition of the classification of the Protozoa, and our -absolute ignorance of the animal matter of Eozoon, render it difficult -to make any statement on this subject more definite than the somewhat -vague intimations given in the text. My own views at present, based on -the study of recent and fossil forms, and of the writings of Carpenter, -Max Schultze, Carter, Wallich, Haeckel, and Clarepede, may be stated, -though with some diffidence, as follows:-- - -I. The class _Rhizopoda_ includes all the sarcodous animals whose only -external organs are pseudopodia, and is the lowest class in the animal -kingdom. Immediately above it are the classes of the Sponges and of the -flagellate and ciliate Infusoria, which rise from it like two diverging -branches. - -II. The group of Rhizopods, as thus defined, includes three leading -_orders_, which, in descending grade, are as follows:-- - - (_a_) _Lobosa_, or AmÅ“boid Rhizopods, including those with - distinct nucleus and pulsating vesicle, and thick lobulate - pseudopodia--naked, or in membranous coverings. - - (_b_) _Radiolaria_, or Polycistius and their allies, including - those with thread-like pseudopodia, with or without a - nucleus, and with the skeleton, when present, silicious. - - (_c_) _Reticularia_, or Foraminifera and their allies, including - those with thread-like and reticulating pseudopodia, with - granular matter instead of a nucleus, and with calcareous, - membranous, or arenaceous skeletons. - -The place of _Eozoon_ will be in the lowest order, _Reticularia_. - -III. The order _Reticularia_ may be farther divided into two -_sub-orders_, as follows:-- - - (_a_) _Perforata_--having calcareous skeletons penetrated with - pores. - - (_b_) _Imperforata_--having calcareous, membranous, or arenaceous - skeletons, without pores. - -The place of Eozoon will be in the higher sub-order, _Perforata_. - -IV. The sub-order _Perforata_ includes three _families_--the -_Nummulinidæ_, _Globigerinidæ_, and _Lagemdæ_. Of these Carpenter -regards the Nummulinidæ as the highest in rank. - -The place of Eozoon will be in the family _Nummulinidæ_, or between -this and the next family. This oldest known Protozoon would thus belong -to the highest family in the highest sub-order of the lowest class of -animals. - - -THE LATE SIR WILLIAM E. LOGAN. - -When writing the dedication of this work, I little thought that the -eminent geologist and valued friend to whom it gave me so much pleasure -to tender this tribute of respect, would have passed away before its -publication. But so it is, and we have now to mourn, not only Lyell, -who so frankly accepted the evidence in favour of Eozoon, but Logan, -who so boldly from the first maintained its true nature as a fossil. -This boldness on his part is the more remarkable and impressive, from -the extreme caution by which he was characterized, and which induced -him to take the most scrupulous pains to verify every new fact before -committing himself to it. Though Sir William's early work in the Welsh -coal-fields, his organization and management of the Survey of Canada, -and his reducing to order for the first time all the widely extended -Palæozoic formations of that great country, must always constitute -leading elements in his reputation, I think that in nothing does he -deserve greater credit than in the skill and genius with which he -attacked the difficult problem of the Laurentian rocks, unravelled -their intricacies, and ascertained their true nature as sediments, and -the leading facts of their arrangement and distribution. The discovery -of Eozoon was one of the results of this great work; and it was the -firm conviction to which Sir William had attained of the sedimentary -character of the rocks, which rendered his mind open to the evidence of -these contained fossils, and induced him even to expect the discovery -of them. - -This would not be the proper place to dwell on the general character -and work of Sir William Logan, but I cannot close without referring to -his untiring industry, his enthusiasm in the investigation of nature, -his cheerful and single-hearted disposition, his earnest public spirit -and patriotism--qualities which won for him the regard even of those -who could little appreciate the details of his work, and which did much -to enable him to attain to the success which he achieved. - - - - -INDEX. - - - Acervuline explained, 66. - - Acervuline Variety of Eozoon, 135. - - Aggregative Growth of Animals, 213. - - Aker Limestone, 197. - - Amity Limestone, 197. - - AmÅ“ba described, 59. - - Annelid Burrows, 133, 139. - - Archæospherinæ, 137, 148. - - Archæocyathus, 151. - - Arisaig, Supposed Eozoon of, 140. - - - Bathybius, 65. - - Bavaria, Eozoon of, 148. - - Beginning of Life, 215. - - Billings, Mr.,--referred to, 41; - on Archæocyathus, 151; - on Receptaculites, 163. - - - Calumet, Eozoon of, 38. - - Calcarina, 74. - - Calcite filling Tubes of Eozoon, 98. - - Canal System of Eozoon, 40, 66, 107, 176, 181. - - Carpenter--referred to, 41; - on Eozoon, 82; - Reply to Carter, 204. - - Caunopora, 158. - - Chrysotile Veins, 107, 180. - - Chemistry of Eozoon, 199. - - Coccoliths, 70. - - CÅ“nostroma, 158. - - Contemporaries of Eozoon, 127. - - Côte St. Pierre, 20. - - - Derivation applied to Eozoon, 225. - - Discovery of Eozoon, 35. - - - Eozoic Time, 7. - - Eozoon,--Discovery of, 35; - Structure of, 65; - Growth of, 70; - Fragments of, 74; - Description of, 65, 77 (also Appendix); - Note on by Dr. Carpenter, 82; - Thickened Walls of, 66; - Preservation of, 100; - Pores filled with Calcite, 97, 109; - with Pyroxene, 108; - with Serpentine, 101; - with Dolomite, 109; - in Limestone, 110; - Defective Specimens of, 113; - how Mineralized, 102, 116; - its Contemporaries, 127; - Acervuline Variety of, 135; - Variety _Minor_ of, 135; - Acadianum, 140; - Bavaricum, 148; - Localities of, 166; - Harmony of with other Fossils, 171; - Summary of evidence relating to, 176. - - - Faulted Eozoon, 182. - - Foraminifera, Notice of, 61. - - Fossils, how Mineralized, 93. - - Fusulina, 74. - - - Glauconite, 100, 125, 220. - - Graphite of Laurentian, 18, 27. - - Green-sand, 99. - - Grenville, Eozoon of, 38. - - Gümbel on Laurentian Fossils, 124; - on Eozoon Bavaricum, 141. - - - Hastings, Rocks of, 57. - - History of Discovery of Eozoon, 35. - - Honeyman, Dr., referred to, 140. - - Hunt, Dr. Sterry, referred to, 35; - on Mineralization of Eozoon, 115; - on Silurian Fossils infiltrated with Silicates, 121; - on Minerals of the Laurentian, 123; - on Laurentian Life, 27; - his Reply 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 Feldspar, 13. - - Laurentian Rocks, 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 Relations of Eozoon, 48; - on Additional Specimens of Eozoon, 52. - - Loganite in Eozoon, 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. - - Silicates mineralizing Fossils, 100, 103, 121, 220. - - Silurian Fossils infiltrated with Silicates, 121. - - Steinhag, Eozoon of, 146. - - Stromatopora, 37, 156. - - Stromatoporidæ, 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 Laurentian, 133, 139. - - -Butler & Tanner. The Selwood Printing Works. Frome, and London. - - - * * * * * - - - - -Transcriber Notes - - -The label Plate II was added to the illustration's page. 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You may copy it, give it away or re-use it under the terms of -the Project Gutenberg License included with this eBook or online at -www.gutenberg.org. If you are not located in the United States, you'll have -to check the laws of the country where you are located before using this ebook. - -Title: Life's Dawn on Earth - Being the history of the oldest known fossil remains, and - their relations to geological time and to the development - of the animal kingdom - -Author: John William, Sir Dawson - -Release Date: December 25, 2015 [EBook #50767] - -Language: English - -Character set encoding: ISO-8859-1 - -*** START OF THIS PROJECT GUTENBERG EBOOK LIFE'S DAWN ON EARTH *** - - - - -Produced by MWS, Tom Cosmas, Bryan Ness and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - - - - - - -</pre> - - -<div class="fig_center" style="width: 246px;"> -<img src="images/cover.jpg" width="246" height="366" alt="cover" /> -</div> - - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_ii" id="Page_ii"></a></span></p> - -<div class="bbox2 fig_center" style="width: 650px;"> -<a name="Plate_I" id="Plate_I"></a> -<p class="tdr">Plate I.</p> - -<img src="images/plate_1.png" width="638" height="393" alt="" /> - -<div class="cap_left">From a Photo. by Henderson</div> -<div class="cap_right">Vincent Brooke, Day & Son. Lith.</div> - -<p class="clear cap_center">CAPE TRINITY ON THE SAGUENAY.</p> - -<p class="cap_center2">A CLIFF OF LAURENTIAN GNEISS.</p> - -<p class="tdr"><i>Frontispiece</i></p> -</div> - - -<p><span class="pagenum"><a name="Page_iii" id="Page_iii"></a></span></p> - - -<p class="title">LIFE’S DAWN ON EARTH:</p> - -<p class="center smaller pmb2">BEING THE</p> - -<div class="fig_center" style="width: 421px;"> -<img src="images/txt_history.png" width="421" height="34" alt="History of the Oldest Known Fossil Remains," /> -</div> - -<p class="center smaller pmt2 pmb2">AND</p> - -<p class="caption3">THEIR RELATIONS TO GEOLOGICAL TIME<br /> -AND TO THE DEVELOPMENT OF<br /> -THE ANIMAL KINGDOM.</p> - - -<p class="center smaller pmt4">BY</p> - -<p class="author">J. W. DAWSON, LL.D., F.R.S., F.G.S., <span class="smcap">Etc.</span>,</p> - -<p class="center smaller">PRINCIPAL AND VICE-CHANCELLOR OF M’GILL UNIVERSITY, MONTREAL;<br /> -AUTHOR OF<br /> -“ARCHAIA,” “ACADIAN GEOLOGY,” “THE STORY OF<br /> -THE EARTH AND MAN,” ETC.</p> - - -<p class="caption3 pmt2"><i>SECOND THOUSAND.</i></p> - - -<p class="caption2 pmt4 pmb4">LONDON:<br /> -HODDER & STOUGHTON,<br /> -27, PATERNOSTER ROW.<br /> -MDCCCLXXV.</p> - -<p><span class="pagenum"><a name="Page_iv" id="Page_iv"></a></span></p> - - -<p class="center smaller pmt4 pmb4"> -Butler & Tanner,<br /> -The Selwood Printing Works,<br /> -Frome, and London.<br /> -</p> - -<p><span class="pagenum"><a name="Page_v" id="Page_v"></a></span></p> - - -<div class="fig_center" style="width: 167px;"> -<img src="images/txt_memory.png" width="167" height="26" alt="To the Memory of" /> -</div> - -<p class="caption2">SIR WILLIAM EDMOND LOGAN,</p> - -<p class="caption3">LL.D., F.R.S., F.G.S.,</p> - -<p class="center smaller">THIS WORK IS DEDICATED,</p> - - -<p>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.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_vi" id="Page_vi"></a><br /> -<a name="Page_vii" id="Page_vii">« vii »</a></span></p> - - - - -<p class="caption2"><a name="PREFACE" id="PREFACE">PREFACE.</a></p> - - -<p>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 attention -turned to this special topic.</p> - -<p>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 -<span class="pagenum"><a name="Page_viii" id="Page_viii">« viii »</a></span> -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.</p> - -<p>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 expense -as a contribution to the work. To Dr. Carpenter -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 Palæozoic Protozoa; and Mr. Weston has aided -greatly by the preparation of slices for the microscope, -and of photographs, as well as by assistance -in collecting.</p> - -<p class="tdr">J. W. D.</p> - -<p><span class="smcap">McGill College, Montreal.</span><br /> - <i>April, 1875.</i></p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_ix" id="Page_ix"></a></span></p> - - - - -<p class="caption2"><a name="CONTENTS" id="CONTENTS">CONTENTS.</a></p> - -<table summary="ToC" style="width: 80%"> -<tr> - <td class="tdl"></td> - <td class="tdr smaller">PAGE</td> -</tr> -<tr> - <td><p class="tdl"><span class="smcap">Chapter I. Introductory</span></p></td> - <td class="tdr"><a href="#CHAPTER_I">1</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Chapter II. The Laurentian System</span></td> - <td class="tdr"><a href="#CHAPTER_II">7</a></td> -</tr> -<tr> - <td><p class="smcap hanging2">Notes:—Logan on Structure of Laurentian; Hunt - on Life in the Laurentian; Laurentian Graphite; - Western Laurentian; Metamorphism</p></td> - <td class="tdr"><a href="#Page_24">24</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Chapter III. The History of a Discovery</span></td> - <td class="tdr"><a href="#CHAPTER_III">35</a></td> -</tr> -<tr> - <td><p class="smcap hanging2">Notes:—Logan on Discovery of Eozoon, and on - Additional Specimens</p></td> - <td class="tdr"><a href="#Page_48">48</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Chapter IV. What is Eozoon?</span></td> - <td class="tdr"><a href="#CHAPTER_IV">59</a></td> -</tr> -<tr> - <td><p class="smcap hanging2">Notes:—Original Description; Note by Dr. Carpenter; - Specimens from Long Lake; Additional Structural Facts</p></td> - <td class="tdr"><a href="#Page_76">76</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Chapter V. Preservation of Eozoon</span></td> - <td class="tdr"><a href="#CHAPTER_V">93</a></td> -</tr> -<tr> - <td><p class="smcap hanging2">Notes:—Hunt on Mineralogy of Eozoon; Silicified - Fossils in Silurian Limestones; Minerals associated with Eozoon; Glauconites</p></td> - <td class="tdr"><a href="#Page_115">115</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Chapter VI. Contemporaries and Successors</span></td> - <td class="tdr"><a href="#CHAPTER_VI">127</a></td> -</tr> -<tr> - <td><p class="smcap hanging2">Notes:—On Stromatoporidæ; Localities of Eozoon</p></td> - <td class="tdr"><a href="#Page_165">165</a></td> -</tr> -<tr> - <td class="tdl"><span class="smcap">Chapter VII. Opponents and Objections</span></td> - <td class="tdr"><a href="#CHAPTER_VII">169</a></td> -</tr> -<tr> - <td><p class="smcap hanging2">Notes:—Objections and Replies; Hunt on - Chemical Objections; Reply by Dr. Carpenter</p></td> - <td class="tdr"><a href="#Page_184">184</a></td> -</tr> -<tr> - <td><p class="tdl"><span class="smcap">Chapter VIII. The Dawn-Animal as a Teacher in Science</span></p></td> - <td class="tdr"><a href="#CHAPTER_VIII">207</a></td> -</tr> -<tr> - <td><p class="tdl"><span class="smcap">Appendix</span></p></td> - <td class="tdr"><a href="#APPENDIX">235</a></td> -</tr> -<tr> - <td><p class="tdl"><span class="smcap">Index</span></p></td> - <td class="tdr"><a href="#INDEX">237</a></td> -</tr> -</table> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_x" id="Page_x"></a><br /><a name="Page_xi" id="Page_xi">« xi »</a></span></p> - - - - -<p class="caption2"><a name="LIST_OF_ILLUSTRATIONS" id="LIST_OF_ILLUSTRATIONS">LIST OF ILLUSTRATIONS.</a></p> - -<hr class="r50" /> - -<p class="caption3">FULL PAGE ILLUSTRATIONS.</p> - -<table summary="LoI" style="width: 80%"> -<tr> - <td></td> - <td></td> - <td class="tdr smaller">TO FACE<br /> - PAGE</td> -</tr> -<tr> - <td class="tdr">I.</td> - <td class="tdl"><span class="smcap">Cape Trinity, from a Photograph</span> (<a href="#Plate_I"><i>Frontispiece</i></a>)</td> - <td class="tdr"></td> -</tr> -<tr> -<td class="tdr">II.</td> - <td class="tdl"><span class="smcap">Map of the Laurentian Region on the River Ottawa</span></td> - <td class="tdr"><a href="#Plate_II">7</a></td> -</tr> -<tr> -<td class="tdr">III.</td> - <td class="tdl"><span class="smcap">Weathered Specimen of Eozoon, from a Photograph</span></td> - <td class="tdr"><a href="#Plate_III">35</a></td> -</tr> -<tr> -<td class="tdr">IV.</td> - <td class="tdl"><span class="smcap">Restoration of Eozoon</span></td> - <td class="tdr"><a href="#Plate_IV">59</a></td> -</tr> -<tr> -<td class="tdr">V.</td> - <td class="tdl"><span class="smcap">Nature-print of Eozoon</span></td> - <td class="tdr"><a href="#Plate_V">93</a></td> -</tr> -<tr> -<td class="tdr">VI.</td> - <td class="tdl"><span class="smcap">Canals of Eozoon, Magnified, from Photographs</span></td> - <td class="tdr"><a href="#Plate_VI">127</a></td> -</tr> -<tr> -<td class="tdr">VII.</td> - <td class="tdl"><span class="smcap">Nature-print of Large Laminated Specimen</span></td> - <td class="tdr"><a href="#Plate_VII">169</a></td> -</tr> -<tr> -<td class="tdr">VIII.</td> - <td class="tdl"><span class="smcap">Eozoon With Chrysotile, etc.</span></td> - <td class="tdr"><a href="#Plate_VIII">207</a></td> -</tr> -</table> - -<p class="caption2">WOODCUTS.</p> - -<table summary="woodcuts" style="width: 80%"> -<tr> - <td class="tdl smaller">FIG.</td> - <td class="tdr smaller">PAGE</td> -</tr> -<tr> - <td class="tdl"> 1. <span class="smcap">General Section</span></td> - <td class="tdr"><a href="#fig_1">9</a></td> -</tr> -<tr> - <td class="tdl"> 2. <span class="smcap">Laurentian Hills</span></td> - <td class="tdr"><a href="#fig_2">11</a></td> -</tr> -<tr> - <td class="tdl"> 3. <span class="smcap">Section of Laurentian</span></td> - <td class="tdr"><a href="#fig_3">13</a></td> -</tr> -<tr> - <td class="tdl"> 4. <span class="smcap">Laurentian Map</span></td> - <td class="tdr"><a href="#fig_4">16</a></td> -</tr> -<tr> - <td class="tdl"> 5. <span class="smcap">Section at St. Pierre</span></td> - <td class="tdr"><a href="#fig_5">22</a></td> -</tr> -<tr> - <td class="tdl"> 6. <span class="smcap">Sketch of Rocks at St. Pierre</span></td> - <td class="tdr"><a href="#fig_6">22</a></td> -</tr> -<tr> - <td class="tdl"> 7. <span class="smcap">Eozoon from Burgess</span></td> - <td class="tdr"><a href="#fig_7">36</a></td> -</tr> -<tr> - <td class="tdl"> 8, 9. <span class="smcap">Eozoon from Calumet</span></td> - <td class="tdr"><a href="#fig_8-9">39</a></td> -</tr> -<tr> - <td class="tdl">10. <span class="smcap">Canals of Eozoon</span></td> - <td class="tdr"><a href="#fig_10">41</a></td> -</tr> -<tr> - <td class="tdl">11. <span class="smcap">Nummuline Wall</span></td> - <td class="tdr"><a href="#fig_11">43</a></td> -</tr> -<tr> - <td class="tdl">12. <span class="smcap">Amœba</span></td> - <td class="tdr"><a href="#fig_12">60</a></td> -</tr> -<tr> - <td class="tdl">13. <span class="smcap">Actinophrys</span></td> - <td class="tdr"><a href="#fig_13">60</a> - <span class="pagenum"><a name="Page_xii" id="Page_xii">« xii »</a></span></td> -</tr> -<tr> - <td class="tdl">14. <span class="smcap">Entosolenia</span></td> - <td class="tdr"><a href="#fig_14">62</a></td> -</tr> -<tr> - <td class="tdl">15. <span class="smcap">Biloculina</span></td> - <td class="tdr"><a href="#fig_15">62</a></td> -</tr> -<tr> - <td class="tdl">16. <span class="smcap">Polystomella</span></td> - <td class="tdr"><a href="#fig_16">62</a></td> -</tr> -<tr> - <td class="tdl">17. <span class="smcap">Polymorphina</span></td> - <td class="tdr"><a href="#fig_17">63</a></td> -</tr> -<tr> - <td class="tdl">18. <span class="smcap">Archæospherinæ</span></td> - <td class="tdr"><a href="#fig_18">67</a></td> -</tr> -<tr> - <td class="tdl">19. <span class="smcap">Nummulites</span></td> - <td class="tdr"><a href="#fig_19">73</a></td> -</tr> -<tr> - <td class="tdl">20. <span class="smcap">Calcarina</span></td> - <td class="tdr"><a href="#fig_20">73</a></td> -</tr> -<tr> - <td class="tdl">21. <span class="smcap">Foraminiferal Rock-builders</span></td> - <td class="tdr"><a href="#fig_21">75</a></td> -</tr> -<tr> - <td class="tdl">21<i>a</i>. <span class="smcap">Casts of Cells of Eozoon</span></td> - <td class="tdr"><a href="#fig_21a">92</a></td> -</tr> -<tr> - <td class="tdl">22. <span class="smcap">Modes of Mineralization</span></td> - <td class="tdr"><a href="#fig_22">96</a></td> -</tr> -<tr> - <td class="tdl">23. <span class="smcap">Silurian Organic Limestone</span></td> - <td class="tdr"><a href="#fig_23">98</a></td> -</tr> -<tr> - <td class="tdl">24. <span class="smcap">Wall of Eozoon Penetrated with Canals</span></td> - <td class="tdr"><a href="#fig_24">98</a></td> -</tr> -<tr> - <td class="tdl">25. <span class="smcap">Crinoid Infiltrated with Silicate</span></td> - <td class="tdr"><a href="#fig_25">103</a></td> -</tr> -<tr> - <td class="tdl">26. <span class="smcap">Shell Infiltrated with Silicate</span></td> - <td class="tdr"><a href="#fig_26">104</a></td> -</tr> -<tr> - <td class="tdl">27. <span class="smcap">Diagram of Proper Wall, etc.</span></td> - <td class="tdr"><a href="#fig_27">106</a></td> -</tr> -<tr> - <td class="tdl">28, 29. <span class="smcap">Casts of Canals</span></td> - <td class="tdr"><a href="#fig_28-29">107</a></td> -</tr> -<tr> - <td class="tdl">30. <span class="smcap">Eozoon from Tudor</span></td> - <td class="tdr"><a href="#fig_30">111</a></td> -</tr> -<tr> - <td class="tdl">31. <span class="smcap">Acervuline Variety of Eozoon</span></td> - <td class="tdr"><a href="#fig_31">135</a></td> -</tr> -<tr> - <td class="tdl">32, 33, 34. <span class="smcap">Archæospherinæ</span></td> - <td class="tdr"><a href="#fig_32-34">137, 138</a></td> -</tr> -<tr> - <td class="tdl">35. <span class="smcap">Annelid Burrows</span></td> - <td class="tdr"><a href="#fig_35">140</a></td> -</tr> -<tr> - <td class="tdl">36. <span class="smcap">Archæospherinæ</span></td> - <td class="tdr"><a href="#fig_36">148</a></td> -</tr> -<tr> - <td class="tdl">37. <span class="smcap">Eozoon Bavaricum</span></td> - <td class="tdr"><a href="#fig_37">149</a></td> -</tr> -<tr> - <td class="tdl">38, 39, 40. <span class="smcap">Archæocyathus</span></td> - <td class="tdr"><a href="#fig_38-39-40">152, 153</a></td> -</tr> -<tr> - <td class="tdl">41. <span class="smcap">Archæocyathus (Structure of)</span></td> - <td class="tdr"><a href="#fig_41">154</a></td> -</tr> -<tr> - <td class="tdl">42. <span class="smcap">Stromatopora</span></td> - <td class="tdr"><a href="#fig_42">157</a></td> -</tr> -<tr> - <td class="tdl">43. <span class="smcap">Stromatopora (Structure of)</span></td> - <td class="tdr"><a href="#fig_43">158</a></td> -</tr> -<tr> - <td class="tdl">44. <span class="smcap">Caunopora</span></td> - <td class="tdr"><a href="#fig_44">159</a></td> -</tr> -<tr> - <td class="tdl">45. <span class="smcap">Cœnostroma</span></td> - <td class="tdr"><a href="#fig_45">160</a></td> -</tr> -<tr> - <td class="tdl">46. <span class="smcap">Receptaculites</span></td> - <td class="tdr"><a href="#fig_46">162</a></td> -</tr> -<tr> - <td class="tdl">47, 48. <span class="smcap">Receptaculites (Structure of)</span></td> - <td class="tdr"><a href="#fig_47-48">163</a></td> -</tr> -<tr> - <td class="tdl">49. <span class="smcap">Laminæ of Eozoon</span></td> - <td class="tdr"><a href="#fig_49">176</a></td> -</tr> -</table> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_1" id="Page_1"></a></span></p> - - -<p class="caption1"><a name="THE_DAWN_OF_LIFE" id="THE_DAWN_OF_LIFE">THE DAWN OF LIFE.</a></p> - - -<hr class="chap" /> - - -<p class="caption2"><a name="CHAPTER_I" id="CHAPTER_I">CHAPTER I.</a><br /> - -INTRODUCTORY.</p> - - -<p>Every one has heard of, or ought to have heard of, -<i>Eozoon Canadense</i>, 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.</p> - -<p>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 introduced; -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 impression -that it would be the most appropriate way -that the great procession of animal existence should -<span class="pagenum"><a name="Page_2" id="Page_2">« 2 »</a></span> -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.</p> - -<p>Do we know the first animal? Can we name it, -explain its structure, and state its relations to its successors? -Can we do this by inference from the succeeding -types of being; and if so, do our anticipations -agree with any actual reality disinterred from the -earth’s crust? If we could do this, either by inference -or actual discovery, how strange it would be to know -that we had before us even the remains of the first -creature that could feel or will, and could place itself -in vital relation with the great powers of inanimate -nature. If we believe in a Creator, we shall feel it a -solemn thing to have access to the first creature into -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 themselves -to the dread alternatives of pain and mortality, -must surely evoke from us that filial reverence which -we owe to the authors of our own being, if they do -not involuntarily draw forth even a superstitious -adoration. The veneration of the old Egyptian for -his sacred animals would be a comparatively reasonable -idolatry, if we could imagine any of these animals -to have been the first that emerged from the domain -of dead matter, and the first link in a reproductive -<span class="pagenum"><a name="Page_3" id="Page_3">« 3 »</a></span> -chain of being that produced all the population of the -world. Independently of any such hypotheses, all -students of nature must regard with surpassing interest -the first bright streaks of light that break on -the long reign of primeval night and death, and presage -the busy day of teeming animal existence.</p> - -<p>No wonder then that geologists have long and -earnestly groped in the rocky archives of the earth in -search of some record of this patriarch of the animal -kingdom. But after long and patient research, there -still remained a large residuum of the oldest rocks, -destitute of all traces of living beings, and designated -by the hopeless name “Azoic,”—the formations destitute -of remains of life, the stony records of a lifeless -world. So the matter remained till the Laurentian -rocks of Canada, lying at the base of these old 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 receive -it. It was regarded with feeble and not very -intelligent faith by many more, and was met with -half-concealed or open scepticism by others. It produced -a copious crop of descriptive and controversial -literature, but for the most part technical, and confined -to scientific transactions and periodicals, read by -very few except specialists. Thus, few even of geological -and biological students have clear ideas of the -real nature and mode of occurrence of these ancient -organisms, and of their relations to better known -forms of life; while the crudest and most inaccurate -<span class="pagenum"><a name="Page_4" id="Page_4">« 4 »</a></span> -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.</p> - -<p>This state of things has long ceased to be desirable -in the interests of science, since the settlement of the -questions raised is in the highest degree important to -the history of life. We cannot, it is true, affirm that -Eozoon is in reality the long sought prototype of animal -existence; but it 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 certain, -if properly entered into, to be fruitful of interesting -and valuable thought, and to form the best possible -introduction to the history of life in connection with -geology.</p> - -<p>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 adequately -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, account -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. -<span class="pagenum"><a name="Page_5" id="Page_5">« 5 »</a></span> -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 successors, -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 has 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.</p> - -<p>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.</p> - -<p>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 elementary -manuals on geology, or “The Story of the Earth -and Man,” by the writer of the present work.</p> - -<p><span class="pagenum"><a name="Page_6" id="Page_6">« 6 »</a></span></p> - -<p class="caption2">TABULAR VIEW OF THE EARTH’S GEOLOGICAL HISTORY.</p> - -<table summary="table"> -<tr class="bbox"> - <td class="center"><i>Animal Kingdom.</i></td> - <td class="center bdl" colspan="3"><i>Geological Periods.</i></td> - <td class="center bdl"><i>Vegetable Kingdom.</i></td> -</tr> -<tr class="bbox"> - <td class="tdl">Age of Man.<br /><br /><br /><br /> - Age of Mammals.</td> - <td class="center bdl">CENOZOIC, OR<br /> - NEOZOIC, OR<br /> - NEOZOIC, OR<br /> - TERTIARY</td> - <td><div class="fig_center" style="width: 11px;"> - <img src="images/bracel_86.png" width="11" height="86" alt="{" /> - </div></td> - <td class="tdl"><span class="smcap">Modern.</span><br /> - <span class="smcap">Post-Pliocene, or Pleistocene.</span><br /> - <span class="smcap">Pliocene.</span><br /> - <span class="smcap">Miocene.</span><br /> - <span class="smcap">Eocene.</span></td> - <td class="tdl bdl">Age of Angiosperms<br /> - and Palms.</td> -</tr> -<tr class="bbox"> - <td class="tdl">Age of Reptiles.</td> - <td class="center bdl">MESOZOIC</td> - <td><div class="fig_center" style="width: 11px;"> - <img src="images/bracel_60.png" width="11" height="60" alt="{" /> - </div></td> - <td class="tdl"><span class="smcap">Cretaceous.</span><br /> - <span class="smcap">Jurassic.</span><br /> - <span class="smcap">Triassic.</span></td> - <td class="tdl bdl">Age of Cycads and<br /> - Pines.</td> -</tr> -<tr class="bbox"> - <td class="tdl">Age of Amphibians<br /> - and Fishes.<br /> - <br /> - Age of Mollusks,<br /> - Corals, and<br /> - Crustaceans.<br /></td> - <td class="center bdl">PALÆOZOIC</td> - <td><div class="fig_center" style="width: 11px;"> - <img src="images/bracel_86.png" width="11" height="86" alt="{" /> - </div></td> - <td class="tdl"><span class="smcap">Permian.</span><br /> - <span class="smcap">Carboniferous.</span><br /> - <span class="smcap">Erian, or Devonian.</span><br /> - <span class="smcap">Upper Silurian.</span><br /> - <span class="smcap">Lower Silurian, or Siluro-Cambrian.</span><br /> - <span class="smcap">Cambrian or Primordial.</span></td> - <td class="tdl bdl">Age of Acrogens and<br /> - Gymnosperms.<br /><br /> - Age of Algæ.</td> -</tr> -<tr class="bbox"> - <td class="tdl">Age of Protozoa,<br /> - and dawn of<br /> - Animal Life.</td> - <td class="center bdl">EOZOIC</td> - <td><div class="fig_center" style="width: 11px;"> - <img src="images/bracel_60.png" width="11" height="60" alt="{" /> - </div></td> - <td class="tdl"><span class="smcap">Huronian.</span> - <span class="smcap">Upper Laurentian.</span><br /> - <span class="smcap">Lower Laurentian.</span></td> - <td class="tdl bdl">Beginning of Age of<br /> - Algæ.</td> -</tr> -</table> - -<div class="bbox2 fig_center" style="width: 660px; margin-top: 2em;"> -<a name="Plate_II" id="Plate_II"></a> -<p class="tdr">Plate II.</p> - -<p class="caption3 pmt2">MAP SHEWING THE DISTRIBUTION OF THE LAURENTIAN LIMESTONES HOLDING EOZOON -IN THE COUNTIES OF OTTAWA & ARGENTEUIL.</p> -<a href="images/plate_2_lrg.png"><img src="images/plate_2.png" width="650" height="387" alt="" /></a> - -<div class="cap_left"><i>Drawn by M. R. Barlow</i></div> -<div class="cap_right"><i>Stanford’s Geog. Estab<sup>t</sup>. Charing Cross, London.</i></div> - -<p class="center clear">Reprinted with additions from the Report of the Geology of Canada, -by Sir W. Logan, F.R.S., 1863.</p> - -<p class="pmt1 smaller center">Click on map to view larger sized image.</p> -</div> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_7" id="Page_7">« 7 »</a></span></p> - - - - -<p class="caption2"><a name="CHAPTER_II" id="CHAPTER_II">CHAPTER II.</a><br /> - -THE LAURENTIAN ROCKS.</p> - - -<p class="p0"><span class="smcap">As</span> we descend in depth and time into the earth’s -crust, after passing through nearly all the vast series -of strata constituting the monuments of geological -history, we at length reach the Eozoic or Laurentian -rocks, deepest and oldest of all the formations known -to the geologist, and more thoroughly altered or -metamorphosed by heat and heated moisture than any -others. These rocks, at one time known as Azoic, -being supposed destitute of all remains of living -things, but now more properly Eozoic, are those in -which the first bright streaks of the dawn of life make -their appearance.<a name="FNanchor_1" id="FNanchor_1"></a><a href="#Footnote_1" class="fnanchor">[A]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_1" id="Footnote_1"></a><a href="#FNanchor_1"><span class="label">[A]</span></a> Dana has recently proposed the term “<i>Archæan</i>,” on the -ground that some of these rocks are as yet unfossiliferous -but as the oldest known part of them contains fossils, there -seems no need for this new name.</p> -</div> - -<p>The name Laurentian, given originally to the -Canadian development of these rocks by Sir William -Logan, but now applied to them throughout the -world, is derived from a range of hills lying north -of the St. Lawrence valley, which the old French -geographers named the Laurentides. In these hills -the harder rocks of this old formation rise to considerable -heights, and form the highlands separating the -<span class="pagenum"><a name="Page_8" id="Page_8">« 8 »</a></span> -St. Lawrence valley from the great plain fronting on -Hudson’s Bay and the Arctic Sea. At first sight it -may seem strange that rocks so ancient should anywhere -appear at the surface, especially on the tops of -hills; but this is a necessary result of the mode of -formation of our continents. The most ancient -sediments deposited in the sea were those first -elevated into land, and first altered and hardened -by heat. Upheaved in the folding of the earth’s -crust into high and rugged ridges, they have either -remained uncovered with newer sediments, or have -had such as were deposited on them washed away; -and being of a hard and resisting nature, they have -remained comparatively unworn when rocks much -more modern have been swept off by denuding -agencies.</p> - -<p>But the exposure of the old Laurentian skeleton of -mother earth is not confined to the Laurentide Hills, -though these have given the formation its name. The -same ancient rocks appear in the Adirondack mountains -of New York, and in the patches which at -lower levels protrude from beneath the newer formations -along the American coast from Newfoundland -to Maryland. The older gneisses of Norway, Sweden, -and the Hebrides, of Bavaria and Bohemia, belong to -the same age, and it is not unlikely that similar rocks -in many other parts of the old continent will be found -to be of as great antiquity. In no part of the world, -however, are the Laurentian rocks more extensively -distributed or better known than in North America; -<span class="pagenum"><a name="Page_9" id="Page_9">« 9 »</a></span> -and to this as the grandest and most -instructive development of them, and -that which first afforded organic remains, -we may more especially devote -our attention. Their general relations -to the other formations of America -may be learned from the rough generalised -section (<a href="#fig_1">fig. 1</a>); in which the -crumpled and contorted Laurentian -strata of Canada are seen to underlie -unconformably the comparatively flat -Silurian beds, which are themselves -among the oldest monuments of the -geological history of the earth.</p> - -<div class="fig_center" style="width: 698px;"> -<a name="fig_1" id="fig_1"></a> -<img src="images/fig_1.png" width="698" height="74" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 1.</span> <i>General Section, showing the Relations of the Laurentian and Palæozoic Rocks in Canada.</i> -(L.) Laurentian. (1.) Cambrian, or Primordial. (2.) Lower Silurian. (3.) Upper Silurian. (4.) Devonian and Carboniferous.</p> -</div> - -<p>The Laurentian rocks, associated -with another series only a little -younger, the Huronian, form a great -belt of broken and hilly country, -extending from Labrador across the -north of Canada to Lake Superior, -and thence bending northward to the -Arctic Sea. Everywhere on the lower -St. Lawrence they appear as ranges -of billowy rounded ridges on the -north side of the river; and as viewed -from the water or the southern shore, -especially when sunset deepens their -tints to blue and violet, they present -a grand and massive appearance, -which, in the eye of the geologist, -<span class="pagenum"><a name="Page_10" id="Page_10">« 10 »</a></span> -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 elevation -would fail to give. (<a href="#fig_2">Fig. 2.</a>) 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.</p> - -<p>The grandeur of the old Laurentian ranges is, however, -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[** insert link in PP]). 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.</p> - -<p><span class="pagenum"><a name="Page_11" id="Page_11">« 11 »</a></span></p> - -<div class="fig_center" style="width: 655px;"> -<a name="fig_2" id="fig_2"></a> -<img src="images/fig_2.png" width="655" height="276" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 2.</span> <i>Laurentian Hills opposite Kamouraska, Lower St. Lawrence.</i></p> - -<p class="cap_center2">The islands in front are Primordial.</p> -</div> - -<p>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 agriculturist, -except in the valleys, which follow the -lines of its softer beds, while it is a favourite region -for the angler, the hunter, and the lumberman. -Many of the Laurentian townships of Canada -<span class="pagenum"><a name="Page_12" id="Page_12">« 12 »</a></span> -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 crystalline -rocks, contorted in the most remarkable manner, -so that if they could be flattened out they would serve -as a skin much too large for mother earth in her -present state, so much has she shrunk and wrinkled -since those youthful days when the Laurentian rocks -were her outer covering. (<a href="#fig_3">Fig. 3.</a>)</p> - -<p>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, consists -of stratified granitic rocks or gneisses, of indurated -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 -<span class="pagenum"><a name="Page_13" id="Page_13">« 13 »</a></span> -with great beds of triclinic feldspar, -especially of that peculiar variety -known as labradorite, or Labrador -feldspar, and which sometimes by its -wonderful iridescent play of colours -becomes a beautiful ornamental -stone.</p> - -<p>I cannot describe such rocks, -but their names will tell something -to those who have any knowledge -of the older crystalline materials -of the earth’s crust. To those who -have not, I would advise a visit -to some cliff on the lower St. Lawrence, -or the Hebridean coasts, or -the shore of Norway, where the -old hard crystalline and gnarled -beds present their sharp edges to -the ever raging sea, and show their -endless alternations of various kinds -and colours of strata often diversified -with veins and nests of crystalline -minerals. He who has seen -and studied such a section of Laurentian -rock cannot forget it.</p> - -<div class="fig_center" style="width: 715px;"> -<a name="fig_3" id="fig_3"></a> -<img src="images/fig_3.png" width="715" height="92" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 3.</span> <i>Section from Petite Nation Seigniory to St. Jerome</i> (60 miles). <i>After Sir W. E. Logan.</i></p> - -<p class="cap_center2">(<i>a, b.</i>) Upper Laurentian. (<i>c.</i>) Fourth gneiss. (<i>d′.</i>) Third limestone. (<i>d.</i>) Third gneiss. (<i>e′.</i>) Second limestone. (<i>x.</i>) Porphyry. -(<i>y.</i>) Granite.</p> -</div> - -<p>All the constituents of the Laurentian -series are in that state -known to geologists as metamorphic. -They were once sandstones, -clays, and limestones, such as -<span class="pagenum"><a name="Page_14" id="Page_14">« 14 »</a></span> -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 observations -of Sorby and of Hunt (the former in connection -with the microscopic structure of rocks, and -the latter in connection with the chemical conditions -of change) show that no very excessive amount of -heat would be required. These observations and those -of Daubrée indicate that crystallization like that of -the Laurentian rocks might take place at a temperature -of not over 370° of the centigrade thermometer.</p> - -<p>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 alternations -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 <a href="#NoteD">Note D</a>.)</p> - -<p><span class="pagenum"><a name="Page_15" id="Page_15">« 15 »</a></span></p> - -<p>It is interesting to notice here that the Laurentian -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 previous -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 unlikely -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.</p> - -<p>However this may be, the distribution and extent -of these pre-Laurentian lands is, and probably ever -<span class="pagenum"><a name="Page_16" id="Page_16">« 16 »</a></span> -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 <a href="#fig_4">fig. 4</a> will show this, and will -also show that the old Laurentian mountains mark -out the future form of the American continent.</p> - -<div class="fig_center" style="width: 364px;"> -<a name="fig_4" id="fig_4"></a> -<img src="images/fig_4.png" width="364" height="358" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 4.</span> <i>The Laurentian Nucleus of the American Continent.</i></p> -</div> - -<p>Rocks 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, -<span class="pagenum"><a name="Page_17" id="Page_17">« 17 »</a></span> -long looked in vain for their actual discovery. Still, -as astronomers have suspected the existence of unknown -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 especially, -have committed themselves to such speculations. -The reasons assigned may be stated thus:—</p> - -<p>Assuming the Laurentian rocks to be altered sediments, -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 geological -age include thicker or more extensive limestones. -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.<a name="FNanchor_2" id="FNanchor_2"></a><a href="#Footnote_2" class="fnanchor">[B]</a> 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 limestones -<span class="pagenum"><a name="Page_18" id="Page_18">« 18 »</a></span> -of the later geological periods. Now, in later -formations, limestone is usually an organic rock, accumulated -by the slow gathering from the sea-water, or -its plants, of calcareous matter, by corals, foraminifera, -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 conformable -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 multitudes -of animals of humble organization were accumulating -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 explained, -or from the error of mistaking the true -bedded limestones for veins of calcareous spar.</p> - -<div class="footnote"> - -<p><a name="Footnote_2" id="Footnote_2"></a><a href="#FNanchor_2"><span class="label">[B]</span></a> Logan: <i>Geology of Canada</i>, p. 45.</p> -</div> - -<p>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 -<span class="pagenum"><a name="Page_19" id="Page_19">« 19 »</a></span> -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.</p> - -<p>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?</p> - -<p>Any one of these reasons might, in itself, be held -insufficient to prove so great and, at first sight, unlikely -a conclusion as that of the existence of abundant -animal and vegetable life in the Laurentian; but the -concurrence of the whole in a series of deposits unquestionably -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.</p> - -<p>Such was the condition of the matter until the -<span class="pagenum"><a name="Page_20" id="Page_20">« 20 »</a></span> -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.</p> - -<p>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, <a href="#fig_3">fig. 3</a>, and -<a href="#Plate_II">map</a>), 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 -Côte 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. André -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 -<span class="pagenum"><a name="Page_21" id="Page_21">« 21 »</a></span> -enormous pines, which constituted the original forest. -Half way we cross the Nation River, 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. André, 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 Côte 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. Love’s original excavation, -whence some of the greater blocks containing Eozoon -were taken, and a larger opening made by an enterprising -American on a vein of fibrous serpentine, -yielding “rock cotton,” for packing steam pistons -and similar purposes. (<a href="#fig_5">Figs. 5 and 6.</a>)</p> - -<p><span class="pagenum"><a name="Page_22" id="Page_22">« 22 »</a></span></p> - -<div class="fig_center" style="width: 376px;"> -<a name="fig_5" id="fig_5"></a> -<img src="images/fig_5.png" width="376" height="182" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 5.</span> <i>Attitude of Limestone at St. Pierre.</i></p> - -<p class="cap_center2">(<i>a.</i>) Gneiss band in the Limestone. (<i>b.</i>) Limestone with Eozoon. (<i>c.</i>) Diorite -and Gneiss.</p> -</div> - -<div class="fig_center" style="width: 384px;"> -<a name="fig_6" id="fig_6"></a> -<img src="images/fig_6.png" width="384" height="266" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 6.</span> <i>Gneiss and Limestone at St. Pierre.</i></p> - -<p class="cap_center2">(<i>a.</i>) Limestone. (<i>b.</i>) Gneiss and Diorite.</p> -</div> - -<p><span class="pagenum"><a name="Page_23" id="Page_23">« 23 »</a></span></p> - -<p>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 -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 -laminæ of serpentine so precisely like the <i>Stromatoporæ</i> -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 palæontologists, 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 Côte St. Pierre are now in that collection -and in my own. A very fine example is represented, -on a reduced scale, in <a href="#Plate_III">Plate. III.</a>, which is taken -from an original photograph.<a name="FNanchor_3" id="FNanchor_3"></a><a href="#Footnote_3" class="fnanchor">[C]</a> In some of the layers -are found other and more minute fossils than Eozoon, -<span class="pagenum"><a name="Page_24" id="Page_24">« 24 »</a></span> -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 limestone. -The section in <a href="#fig_5">fig. 5</a> will serve to show the -attitude of the limestone at this place, while the more -general section, <a href="#fig_3">fig. 3</a>, taken from Sir William Logan, -shows its relation to the other Laurentian rocks, and -the sketch in <a href="#fig_6">fig. 6</a> shows its appearance as a feature -on the surface of the country.</p> - -<div class="footnote"> - -<p><a name="Footnote_3" id="Footnote_3"></a><a href="#FNanchor_3"><span class="label">[C]</span></a> By Mr. Weston, of the Geological Survey of Canada.</p> -</div> - - -<hr class="r20" /> - -<p class="caption3">NOTES TO CHAPTER II.</p> - - -<p class="center">(A.) <span class="smcap">Sir William E. Logan on the Laurentian System.</span></p> - -<p class="center smaller">[<i>Journal of Geological Society of London</i>, February, 1865.]</p> - -<div class="blockquot"> - -<p>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:—</p> - -<p>"The united thickness of these two groups in Canada cannot -be less than 30,000 feet, and probably much exceeds it. -The Laurentian of the west of Scotland, according to Sir Roderick -Murchison, also attains a great thickness. In that region -the Upper Laurentian or Labrador series, has not yet been -<span class="pagenum"><a name="Page_25" id="Page_25">« 25 »</a></span> -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 Emmons, -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 <i>Canadian Naturalist</i> -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 formation, -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.</p> - -<p>"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 Murchison, turning his attention to this central -European mass, placed it on the same horizon. These rocks, -underlying Barrande’s Primordial zone, with a great development -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 Gümbel -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, -Gümbel and Crejci account for its presence by an inverted -fold in the strata; while Sir Roderick places this at the base, -and regards the whole as a single series, in the normal fundamental -position of the Laurentian of Scotland and of Canada. -<span class="pagenum"><a name="Page_26" id="Page_26">« 26 »</a></span> -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.</p> - -<p>"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 contact.</p> - -<p>"The united thickness of these three great series may possibly -far surpass that of all the succeeding rocks from the -base of the Palæozoic 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 mechanical -processes which have ever since been at work disintegrating -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 crystalline -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.</p> - -<p>"In both the Upper and Lower Laurentian series there are -several zones of limestone, each of sufficient volume to constitute -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 certainty -either the base or the summit of this series, these three -may be conformably followed by many more. Although the -<span class="pagenum"><a name="Page_27" id="Page_27">« 27 »</a></span> -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."</p> -</div> - - -<p class="center">(B.) <span class="smcap">Dr. Sterry Hunt on the Probable Existence of -Life in the Laurentian Period.</span></p> - -<div class="blockquot"> - -<p>Dr. Hunt’s views on this subject were expressed in the -<i>American Journal of Science</i>, [2], vol. xxxi., p. 395. From this -article, written in 1861, after the announcement of the existence -of laminated forms supposed to be organic in the Laurentian, -by Sir W. E. Logan, but before their structure and -affinities had been ascertained, I quote the following sentences:—</p> - -<p>“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 oxidation, -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.”</p> -</div> - - -<p class="center">(C.) <span class="smcap">The Graphite of the Laurentian.</span></p> - -<div class="blockquot"> - -<p>The following is from a paper by the author, in the <i>Journal -of the Geological Society</i>, for February, 1870:—</p> - -<p>“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 -<span class="pagenum"><a name="Page_28" id="Page_28">« 28 »</a></span> -containing rock. Sir William Logan states<a name="FNanchor_4" id="FNanchor_4"></a><a href="#Footnote_4" class="fnanchor">[D]</a> that ‘the deposits -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 disseminated -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 corrugated -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 it as possible that it may have been in a -state of aqueous solution;<a name="FNanchor_5" id="FNanchor_5"></a><a href="#Footnote_5" class="fnanchor">[E]</a> 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.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_4" id="Footnote_4"></a><a href="#FNanchor_4"><span class="label">[D]</span></a> <i>Geology of Canada</i>, 1863.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_5" id="Footnote_5"></a><a href="#FNanchor_5"><span class="label">[E]</span></a> <i>Report of the Geological Survey of Canada</i>, 1866.</p> - -<p><span class="pagenum"><a name="Page_29" id="Page_29">« 29 »</a></span></p> -</div> - -<div class="blockquot"> - -<p>“The quantity of graphite in the Lower Laurentian series is -enormous. In a recent visit to the township of Buckingham, -on the Ottawa River, 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 extent -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.<a name="FNanchor_6" id="FNanchor_6"></a><a href="#Footnote_6" class="fnanchor">[F]</a></p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_6" id="Footnote_6"></a><a href="#FNanchor_6"><span class="label">[F]</span></a> Matthew, in <i>Quart. Journ. Geol. Soc.</i>, vol. xxi., p. 423. <i>Acadian -Geology</i>, p. 662.</p> -</div> - -<p><span class="pagenum"><a name="Page_30" id="Page_30">« 30 »</a></span></p> - -<div class="blockquot"> - -<p>“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 -cases, in the first instance, from the deoxidation of carbonic -acid by living plants. No other source of carbon can, I -believe, be imagined in the Laurentian period. We may, however, -suppose either that the graphitic matter of the Laurentian -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 Rhode Island. These instances, however, -are exceptional, and the greater part of the disseminated and -vein graphite might rather be compared in its mode of occurrence -to the bituminous matter in bituminous shales and -limestones.</p> - -<p>“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 metamorphosed -and converted into graphitic rocks not dissimilar -to those in the less altered portions of the Laurentian.<a name="FNanchor_7" id="FNanchor_7"></a><a href="#Footnote_7" class="fnanchor">[G]</a> 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 resistance, -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 Dorchester -and Hillsborough, New Brunswick, with an arrangement -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 transverse -columnar structure, and regarded by Logan and Hunt -as an altered bitumen. These palæozoic 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 -<span class="pagenum"><a name="Page_31" id="Page_31">« 31 »</a></span> -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.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_7" id="Footnote_7"></a><a href="#FNanchor_7"><span class="label">[G]</span></a> Granby, Melbourne, Owl’s Head, etc., <i>Geology of Canada</i>, 1863, -p. 599.</p> -</div> - -<div class="blockquot"> - -<p>“Dr. Hunt has, however, observed an indication of terrestrial -vegetation, or at least of subaërial 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 Newborough, -200 feet thick,<a name="FNanchor_8" id="FNanchor_8"></a><a href="#Footnote_8" class="fnanchor">[H]</a> 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.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_8" id="Footnote_8"></a><a href="#FNanchor_8"><span class="label">[H]</span></a> <i>Geology of Canada</i>, 1863.</p> -</div> - -<p><span class="pagenum"><a name="Page_32" id="Page_32">« 32 »</a></span></p> - -<div class="blockquot"> - -<p>“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, algæ have been converted into bituminous -matter, we cannot ordinarily obtain any structural evidence 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 bituminous -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, sometimes -of much beauty. In correspondence with this, while in -some Laurentian graphitic rocks, as, for instance, in the compact -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 -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.</p> - -<p>“When palæozoic 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 (<i>Dadoxylon ouangondianum</i>) 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.<a name="FNanchor_9" id="FNanchor_9"></a><a href="#Footnote_9" class="fnanchor">[I]</a> -No structures so perfect have as yet been detected -in the Laurentian, though in the largest of the three -graphitic beds at St. John there appear to be fibrous structures -which I believe may indicate the existence of land-plants. -This graphite is composed of contorted and slickensided -laminæ, 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.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_9" id="Footnote_9"></a><a href="#FNanchor_9"><span class="label">[I]</span></a> <i>Acadian Geology</i>, p. 535. In calcified specimens the structures -remain in the graphite after decalcification by an acid.</p> -</div> - -<p><span class="pagenum"><a name="Page_33" id="Page_33">« 33 »</a></span></p> - -<div class="blockquot"> - -<p>“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 -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 Algæ.</p> - -<p>“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 structure -of the substance corresponds with that of the carbonaceous -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 existed -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.”</p> -</div> - - -<p class="center"><a name="NoteD" id="NoteD"></a>(D.) <span class="smcap">Western and other Laurentian Rocks, etc.</span></p> - -<div class="blockquot"> - -<p>In the map of the Laurentian nucleus of America (<a href="#fig_4">fig. 4</a>,) -I have not inserted the Laurentian rocks believed to exist in -the Rocky Mountains and other western ranges. Their distribution -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 Laurentian -in the north of Newfoundland, and it should be wider at -the west end of lake Superior.</p> - -<p>Full details as to the Laurentian rocks of Canada and sectional -<span class="pagenum"><a name="Page_34" id="Page_34">« 34 »</a></span> -lists of their beds will be found in the <i>Reports of the -Geological Survey</i>, and Dr. Hunt has discussed very fully -their chemical characters and metamorphism in his <i>Chemical -and Geological Essays</i>. 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 unconformably -on these, others corresponding to the Upper Laurentian; -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. -Hayden’s report describes granitic and gneissose rocks, probably -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.</p> - -<p>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 particles -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 <i>Hunt’s -Essays</i>, p. 24.)</p> -</div> - -<div class="bbox2 fig_center" style="width: 650px;"> -<a name="Plate_III" id="Plate_III"></a> -<p class="tdr">Plate III.</p> -<div class="fig_center" style="width: 626px;"> - -<img src="images/plate_3.png" width="626" height="432" alt="" /> - -<div class="cap_left">From a Photo by Weston.</div> -<div class="cap_right">Vincent Brooks, Day & Son, Lith.</div> - -<p class="clear cap_center">WEATHERED SPECIMEN OF EOZOON CANADENSE. -(ONE-HALF NATURAL SIZE.)</p> - -<p class="tdr"><i>To face Chap. 3</i></p> -</div> -</div> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_35" id="Page_35">« 35 »</a></span></p> - - - -<p class="caption2"><a name="CHAPTER_III" id="CHAPTER_III">CHAPTER III.</a><br /> - -THE HISTORY OF A DISCOVERY.</p> - - -<p class="p0"><span class="smcap">It</span> 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 before -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 examination -of the rocks and minerals by Dr. Sterry Hunt. -On the other hand, Dr. Carpenter and others in England -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 dissimilar -branches of scientific inquiry were destined to be -united by a series of happy discoveries, made not fortuitously -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 zoological -<span class="pagenum"><a name="Page_36" id="Page_36">« 36 »</a></span> -and palæontological knowledge, and the surveys -previously made, whereby the age and distribution -of the Laurentian rocks and the chemical conditions -of their deposition and metamorphism were ascertained.</p> - -<div class="fig_center" style="width: 401px;"> -<a name="fig_7" id="fig_7"></a> -<img src="images/fig_7.png" width="401" height="212" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 7.</span> <i>Eozoon mineralized by Loganite and Dolomite.</i></p> - -<p class="cap_center2">(Collected by Dr. Wilson, of Perth.)</p> -</div> - -<p>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 laminæ of a dark green mineral -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 <a href="#fig_7">fig. 7</a>. 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 pyroxene, -<span class="pagenum"><a name="Page_37" id="Page_37">« 37 »</a></span> -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 -seem to have at once struck Sir W. E. Logan as resembling -the Silurian fossils known as <i>Stromatopora</i>, -and he showed them to Mr. Billings, the palæontologist -of the survey, and to the writer, with this suggestion, -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 affirming -the organic nature of such specimens; and my own -suggestion was that they should be sliced, and examined -microscopically, and that if fossils, as they -presented merely concentric laminæ 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 Laurentian -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 Report -of the Geological Survey, summing up its work -<span class="pagenum"><a name="Page_38" id="Page_38">« 38 »</a></span> -to that time, was published, under the name of the -<i>Geology of Canada</i>, 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. -(<a href="#fig_8-9">Figs. 8 and 9.</a>)</p> - -<p>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 exception -to this, stating that though in the slices before -examined no structure was apparent, still my impression -was that the calcareous matter was the fossil, and -the serpentine or loganite the filling. He said—“In -that case, would it not be well to re-examine the specimens, -and 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 -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 specimens -in my collection presented by him, was evidently -of the same type with that preserved in the canals of -these ancient fossils. <a href="#fig_10">Fig. 10</a> is an accurate representation -of the first seen group of canals penetrated by -serpentine.</p> - -<p><span class="pagenum"><a name="Page_39" id="Page_39">« 39 »</a></span></p> - -<div class="fig_center" style="width: 382px;"> -<a name="fig_8-9" id="fig_8-9"></a> -<img src="images/fig_8.png" width="382" height="303" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 8.</span> <i>Weathered Specimen of Eozoon from the Calumet.</i></p> - -<p class="cap_center2">(Collected by Mr. McMullen.)</p> -</div> - -<div class="fig_center" style="width: 380px;"> -<a name="fig_9" id="fig_9"></a> -<img src="images/fig_9.png" width="380" height="221" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 9.</span> <i>Cross Section of the Specimen represented in <a href="#fig_8-9">Fig. 8.</a></i></p> - -<p class="cap_center2">The dark parts are the laminæ of calcareous matter converging to the outer -surface.</p> -</div> - -<p><span class="pagenum"><a name="Page_40" id="Page_40">« 40 »</a></span></p> - -<p>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.</p> - -<p>Feeling that the discovery was most important, but -that it would be met with determined scepticism by a -great many geologists, I was not content with examining -the typical specimens of Eozoon, but had slices -prepared of every variety of Laurentian limestone, of -altered limestones from the Primordial and Silurian, -<span class="pagenum"><a name="Page_41" id="Page_41">« 41 »</a></span> -and of serpentine marbles of all the varieties furnished -by our collections. These were examined with ordinary -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; -and of some of the more important structures beautiful -drawings were executed by the late Mr. H. S. -Smith, the then palæontological 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 occurring -in these or other limestones.</p> - -<div class="fig_center" style="width: 278px;"> -<a name="fig_10" id="fig_10"></a> -<img src="images/fig_10.png" width="278" height="260" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 10.</span> <i>Group of Canals in the Supplemental Skeleton of Eozoon.</i></p> - -<p class="cap_center2">Taken from the specimen in which they were first recognised. Magnified.</p> -</div> - -<p><span class="pagenum"><a name="Page_42" id="Page_42">« 42 »</a></span></p> - -<p>At this stage of the matter, and after exhibiting to -Sir William all the characteristic appearances in comparison -with such concretionary, dendritic, and crystalline -structures as most resembled them, and also with -the structure of recent and fossil Foraminifera, I -suggested that the further prosecution of the matter -should be handed over to Mr. Billings, as palæontologist -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 appearances -of Foraminifera or of mineral substances. -It was finally arranged that I should prepare a description -of the fossil, which Sir William would take to -London, along with Dr. Hunt’s notes, the more important -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 -<span class="pagenum"><a name="Page_43" id="Page_43">« 43 »</a></span> -cell-wall, which I had not observed previously through -a curious accident as to specimens.<a name="FNanchor_10" id="FNanchor_10"></a><a href="#Footnote_10" class="fnanchor">[J]</a> Mr. Lowe had -been sent back to the Ottawa to explore, and just before -Sir William’s departure had sent in some specimens -from a new locality at Petite Nation, similar in -general appearance to those from Grenville, which Sir -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 -<span class="pagenum"><a name="Page_44" id="Page_44">« 44 »</a></span> -Grenville specimens, and which I did not see until -after it had been detected by Dr. Carpenter in London. -Dr. Carpenter thus contributed in a very important -manner to the perfecting of the investigations -begun in Canada, and on him has fallen the greater -part of their illustration and defence,<a name="FNanchor_11" id="FNanchor_11"></a><a href="#Footnote_11" class="fnanchor">[K]</a> in so far as Great -Britain is concerned. <a href="#fig_11">Fig. 11</a>, taken from one of Dr. -Carpenter’s papers, shows the tubulated primitive wall -as described by him.</p> - -<div class="footnote"> - -<p><a name="Footnote_10" id="Footnote_10"></a><a href="#FNanchor_10"><span class="label">[J]</span></a> In papers by Dr. Carpenter, subsequently referred to. -Prof. Jones published an able exposition of the facts in the -<i>Popular Science Monthly</i>.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_11" id="Footnote_11"></a><a href="#FNanchor_11"><span class="label">[K]</span></a> In <i>Quarterly Journal of Geological Society</i>, vol. xxii.; <i>Proc. -Royal Society</i>, vol. xv.; <i>Intellectual Observer</i>, 1865. <i>Annals -and Magazine of Natural History</i>, 1874; and other papers and -notices.</p> -</div> - -<div class="fig_center" style="width: 432px;"> -<a name="fig_11" id="fig_11"></a> -<img src="images/fig_11.png" width="432" height="296" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 11.</span> <i>Portion of Eozoon magnified 100 diameters, showing the -original Cell-wall with Tubulation, and the Supplemental Skeleton -with Canals.</i> (<i>After Carpenter.</i>)</p> - -<p class="cap_center2">(<i>a.</i>) Original tubulated wall or “Nummuline layer,” more magnified in fig. 2. -(<i>b, c.</i>) “Intermediate skeleton,” with canals.</p> -</div> - -<p>The immediate result was a composite paper in the -<i>Proceedings of the Geological Society</i>, by Sir W. E. -Logan, Dr. Carpenter, Dr. Hunt, and myself, in which -the geology, palæontology, and mineralogy of <i>Eozoon -Canadense</i> and its containing rocks were first given to -the world.<a name="FNanchor_12" id="FNanchor_12"></a><a href="#Footnote_12" class="fnanchor">[L]</a> It cannot be wondered at that when -geologists and palæontologists were thus required to -believe in the existence of organic remains in rocks -regarded as altogether Azoic and hopelessly barren of -fossils, and to carry back the dawn of life as far before -those Primordial rocks, which were supposed to contain -its first traces, as these are before the middle -period of the earth’s life history, some 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 -<span class="pagenum"><a name="Page_45" id="Page_45">« 45 »</a></span> -types of animals, and of the conditions of mineralization -of organic remains, possessed by few even of professional -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.</p> - -<div class="footnote"> - -<p><a name="Footnote_12" id="Footnote_12"></a><a href="#FNanchor_12"><span class="label">[L]</span></a> <i>Journal Geological Society</i>, February, 1865.</p> -</div> - -<p>“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 Palæozoic -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 comparatively -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 extension -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 specimens -in the Upper Laurentian or Huronian of Tudor. -<span class="pagenum"><a name="Page_46" id="Page_46">« 46 »</a></span> -Gümbel recognised the organism in Laurentian Rocks -in Bavaria and elsewhere in Europe, and discovered a -new species in the Huronian of Bavaria.<a name="FNanchor_13" id="FNanchor_13"></a><a href="#Footnote_13" class="fnanchor">[M]</a> Eozoon -was recognised in Laurentian limestones in Massachusetts<a name="FNanchor_14" id="FNanchor_14"></a><a href="#Footnote_14" class="fnanchor">[N]</a> -and New York, and there has been a rapid -growth of new facts increasing our knowledge of Foraminifera -of similar types in the succeeding Palæozoic -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 vindication -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 specimens -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-examine -the locality at Petite Nation originally discovered -by Mr. Lowe, and am prepared to show that all -the facts with reference to the mode of occurrence of -<span class="pagenum"><a name="Page_47" id="Page_47">« 47 »</a></span> -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.</p> - -<div class="footnote"> - -<p><a name="Footnote_13" id="Footnote_13"></a><a href="#FNanchor_13"><span class="label">[M]</span></a> <i>Ueber das Vorkommen von Eozoon</i>, 1866.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_14" id="Footnote_14"></a><a href="#FNanchor_14"><span class="label">[N]</span></a> By Mr. Bicknell at Newbury, and Mr. Burbank at Chelmsford. -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 Chelmsford -specimens and in those of Warren, New York, is in small -and rare fragments in serpentinous limestone.</p> -</div> - -<p>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 accumulations -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.</p> - -<p>Other discoveries also are foreshadowed here. The -microscope may yet detect the true nature and affinities -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 -<span class="pagenum"><a name="Page_48" id="Page_48">« 48 »</a></span> -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 Laurentian -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 latter -are when compared with modern forests?</p> - - -<hr class="r20" /> - -<p class="caption3">NOTES TO CHAPTER III.</p> - - -<p class="center">(A.) <span class="smcap">Sir William E. Logan on the Discovery and -Characters of Eozoon.</span></p> - -<p class="center smaller">[<i>Journal of Geological Society</i>, February, 1865.]</p> - -<div class="blockquot"> - -<p>"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 limestones -did not seem to offer a proof in the negative, any more -than their undiscovered presence in newer crystalline limestones -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, has 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;<a name="FNanchor_15" id="FNanchor_15"></a><a href="#Footnote_15" class="fnanchor">[O]</a> 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 -<span class="pagenum"><a name="Page_49" id="Page_49">« 49 »</a></span> -Geological Survey of the province, from one of the limestones -of the Laurentian series occurring at the Grand Calumet, on -the river Ottawa.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_15" id="Footnote_15"></a><a href="#FNanchor_15"><span class="label">[O]</span></a> <i>Quarterly Journal of the Geological Society</i>, xv., 493.</p> -</div> - -<div class="blockquot"> - -<p>"Any organic remains which may have been entombed in -these limestones would, if they retained their calcareous character, -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 concentric -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 <i>Geology of Canada</i>, -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 <i>Canadian Naturalist</i>, 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 the exception of my friend -Professor Ramsay.</p> - -<p>"One of the specimens had been sliced and submitted to -microscopic observation, but unfortunately it was one of those -<span class="pagenum"><a name="Page_50" id="Page_50">« 50 »</a></span> -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 accidentally -observed indications of similar forms in blocks of Laurentian -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 microscope, -the minute structure was observed in the first one -submitted to inspection. At the request of Mr. Billings, the -palæontologist 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 communication. -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 -Foraminifer, 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 resembling -that of other Foraminiferal forms, as, for example -Calcarina and Nummulina.</p> - -<p>"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, serpentine, -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 consecutive -stages of a continuous process. In the Burgess specimens, -while the sarcode is replaced by loganite, the calcareous skeleton, -as has already been stated, has been replaced by dolomite, -<span class="pagenum"><a name="Page_51" id="Page_51">« 51 »</a></span> -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 Foraminifera, -and that of the allied forms in Tertiary and recent deposits -(which, as Ehrenberg, Bailey, and Pourtales have shown, -are injected with glauconite), is obvious.</p> - -<p>"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 overlying -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 limestone, -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 irregular -masses of white crystalline pyroxene, some of them twenty -yards in length by four or five wide. They appear to be confusedly -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 -<span class="pagenum"><a name="Page_52" id="Page_52">« 52 »</a></span> -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 perhaps -more. Other parts, immediately on the outside of the -sheet of serpentine, are occupied with about the same thickness -of what appear to be the ruins of the fossil, broken up -into a more or less granular mixture of calc-spar and serpentine, -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 disseminated -leaves of graphite.</p> - -<p>“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 portion, -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-serpentinous -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 recent -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.”</p> -</div> - -<p class="center"><a name="NoteB" id="NoteB"></a>(B.) <span class="smcap">NOTE BY SIR WILLIAM E. LOGAN, ON ADDITIONAL -SPECIMENS OF EOZOON.</span></p> - -<p class="center smaller">[<i>Journal of Geological Society</i>, August, 1867.]</p> - -<div class="blockquot"> - -<p>"Since the subject of Laurentian fossils was placed before -this Society in the papers of Dr. Dawson, Dr. Carpenter, Dr. -<span class="pagenum"><a name="Page_53" id="Page_53">« 53 »</a></span> -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 examination -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 specimens -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.</p> - -<p>"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 limestone, -white coarsely granular limestone, and bands of dark -bluish compact limestone and black pyritiferous slates, to the -whole of which Mr. Vennor 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 appended, -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.</p> - -<p>"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 therefore -supposed that the Hastings series may be somewhat -<span class="pagenum"><a name="Page_54" id="Page_54">« 54 »</a></span> -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 anorthosite -rock, rising about 150 feet above the general plain, and -supposed to belong to the unconformable Upper Laurentian."</p> - -<p>[Subsequent observations, however, render it probable that -some of the above beds may be Huronian.]</p> - -<p>"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 outline -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 <i>Geology of Canada</i>, 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 specimen -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 -<span class="pagenum"><a name="Page_55" id="Page_55">« 55 »</a></span> -from Dr. Dawson by Dr. Carpenter in the Journal of this -Society for August, 1866.</p> - -<p>"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 Grenville -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 Côte 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 Côte 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 limestone, -which has somewhat the aspect of a conglomerate, -specimens have been obtained resembling some of the figures -given by Gümbel in his <i>Illustrations</i> of the forms met with -by him in the Laurentian rocks of Bavaria.</p> - -<p>"In decalcifying by means of a dilute acid some of the -specimens from Côte 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 bruising. -There is little doubt that these portions of the skeleton -are partially replaced by dolomite, as more recent fossils are -<span class="pagenum"><a name="Page_56" id="Page_56">« 56 »</a></span> -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 investigation -of the locality some spots will be found to yield -specimens in which the calcareous skeleton still exists unreplaced -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 Côte St. Pierre.</p> - -<p class="pmb2">"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 Laurentian -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 minerals, -pyroxene and serpentine. Now we have it imbedded in -limestone, just as most fossils are. In every case, with the exception -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, therefore, -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 organism -<span class="pagenum"><a name="Page_57" id="Page_57">« 57 »</a></span> -have been made by Professors King and Rowney: but -these appear to me to be based upon the supposition that because -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 -Rowney passed in review before him prior to his coming to -the conclusions which he has published."</p> -</div> - -<p><span class="pagenum"><a name="Page_58" id="Page_58">« 58 »</a></span></p> - -<p class="caption3"><i>Ascending Section of the Eozoic Rocks in the County of -Hastings, Ontario.</i> By Mr. <span class="smcap">H. G. Vennor</span>.</p> - -<table summary="section"> -<tr> - <td></td> - <td class="tdr smaller">Feet.</td> -</tr> -<tr> - <td class="tdl">1. Reddish and flesh-coloured granitic gneiss, the thickness - of which is unknown; estimated at not less than</td> - <td class="tdr vbot">2,000</td> -</tr> -<tr> - <td class="tdl">2. Grayish and flesh-coloured gneiss, sometimes hornblendic, - passing towards the summit into a dark mica-schist, - and including portions of greenish-white diorite; - mean of several pretty closely agreeing measurements,</td> - <td class="tdr vbot">10,400</td> -</tr> -<tr> - <td class="tdl">3. Crystalline limestone, sometimes magnesian, including - lenticular patches of quartz, and broken and - contorted layers of quartzo-felspathic rock, rarely above - a few inches in thickness. This limestone, which includes - in Elzivir a one-foot bed of graphite, is sometimes - very thin, but in other places attains a thickness - of 750 feet; estimated as averaging</td> - <td class="tdr vbot">400</td> -</tr> -<tr> - <td class="tdl">4. Hornblendic and dioritic rocks, massive or schistose, - occasionally associated near the base with dark - micaceous schists, and also with chloritic and epidotic - rocks, including beds of magnetite; average thickness</td> - <td class="tdr vbot">4,200</td> -</tr> -<tr> - <td class="tdl">5. Crystalline and somewhat granular magnesian - limestone, occasionally interstratified with diorites, and - near the base with silicious slates and small beds of - impure steatite</td> - <td class="tdr vbot">330</td> -</tr> -<tr> - <td class="tdl">This limestone, which is often silicious and ferruginous, - 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.</td> - <td></td> -</tr> -<tr> - <td class="tdl">6. Gray silicious or fined-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</td> - <td class="tdr vbot">400</td> -</tr> -<tr> - <td class="tdl">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</td> - <td class="tdr vbot">500</td> -</tr> -<tr> - <td class="tdl">8. Gneissoid micaceous quartzites, banded gray and - white, with a few interstratified beds of silicious limestone, - and, like the last division, weathering rusty brown</td> - <td class="tdr vbot">1,900</td> -</tr> -<tr> - <td class="tdl">9. Gray micaceous limestone, sometimes plumbaginous, - 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</td> - <td class="tdr vbot">1,100</td> -</tr> -<tr> - <td class="tdl">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.</td> - <td></td> -</tr> -<tr> - <td class="tdr">Total thickness </td> - <td class="tdr bdt">21,130</td> -</tr> -</table> - -<div class="fig_center bbox2" style="margin-top: 2em; width: 400px;"> -<a name="Plate_IV" id="Plate_IV"></a> - -<p class="tdr">PLATE IV.</p> - -<img src="images/plate_4.png" width="285" height="471" alt="" /> - -<p class="cap_center"><i>Magnified and Restored Section of a portion of Eozoon Canadense.</i></p> - -<p class="cap_center2">The portions in brown show the animal matter of the Chambers, Tubuli, -Canals, and Pseudopodia; the portions uncoloured, the calcareous skeleton.</p> -</div> - -<p><span class="pagenum"><a name="Page_59" id="Page_59">« 59 »</a></span></p> - -<div><a name="fig_12" id="fig_12"></a><a name="fig_13" id="fig_13"></a> -<table summary="Fig 12-13"> -<tr> - <td><img src="images/fig_12.png" width="127" height="155" alt="" /></td> - <td><img src="images/fig_13.png" width="254" height="252" alt="" /></td> -</tr> -<tr> - <td class="cap_center" colspan="2"><span class="smcap">Fig. 12.</span> <i>Amœba.</i> <span class="smcap">Fig. 13.</span> <i>Actinophrys.</i></td> -</tr> -<tr> - <td class="cap_center2" colspan="2">From original sketches.</td> -</tr> -</table> -</div> - - -<hr class="chap" /> - - -<p class="caption2"><a name="CHAPTER_IV" id="CHAPTER_IV">CHAPTER IV.</a><br /> - -WHAT IS EOZOON?</p> - - -<p class="p0"><span class="smcap">The</span> 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 -<i>Amœba</i><a name="FNanchor_16" id="FNanchor_16"></a><a href="#Footnote_16" class="fnanchor">[P]</a> (<a href="#fig_12">fig. 12</a>), 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 pseudopods -which serve as extempore limbs. When moving -on the surface of a slip of glass under the microscope, -it seems, as it were, to flow along rather than creep, -and its body appears to be of a semi-fluid consistency. -It may be taken as an example of the least complex -forms of animal life known to us, and is often spoken -of by naturalists as if it were merely a little particle -of living and scarcely organized jelly or protoplasm. -When minutely examined, however, it will not be found -so simple as it at first sight appears. Its outer layer -<span class="pagenum"><a name="Page_60" id="Page_60">« 60 »</a></span> -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, -which is a little cell capable, at certain times, of producing -by its division new individuals. Food when -taken in through the wall of the body forms little -pellets, which become surrounded by a 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 -<span class="pagenum"><a name="Page_61" id="Page_61">« 61 »</a></span> -body is capable of protrusion in any direction into long -processes, which are very mobile, and used for locomotion -and prehension. Further, this creature, though -destitute of most of the parts which we are accustomed -to regard as proper to animals, seems to exercise volition, -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 -Amœba are found other types of equally simple Protozoa, -but somewhat differently organized. One of -these, <i>Actinophrys</i> (<a href="#fig_13">fig. 13</a>), has the body globular and -unchanging in form, the outer wall of greater thickness; -the pulsating vesicle like a blister on the surface, -and the pseudopods long and thread-like. Its habits -are similar to those of the Amœba, and I introduce it -to show the variations of form and structure possible -even among these simple creatures.</p> - -<div class="footnote"> - -<p><a name="Footnote_16" id="Footnote_16"></a><a href="#FNanchor_16"><span class="label">[P]</span></a> The alternating animal, alluding to its change of form.</p> - -<p><span class="pagenum"><a name="Page_62" id="Page_62">« 62 »</a></span></p> -</div> - -<div> -<a name="fig_14" id="fig_14"></a><a name="fig_15" id="fig_15"></a> -<a name="fig_16" id="fig_16"></a><a name="fig_17" id="fig_17"></a> - -<table summary="fig. 14-17"> -<tr> - <td class="center" style="width:150px"><img src="images/fig_14.png" width="105" height="112" alt="" /></td> - <td class="center" style="width:150px"><img src="images/fig_15.png" width="102" height="176" alt="" /></td> -</tr> -<tr> - <td class="vtop"><p class="cap_center"><span class="smcap">Fig. 14.</span> <i>Entosolenia.</i></p> - <p class="cap_center2">A one-celled Foraminifer.<br />Magnified as a transparent object.</p></td> - <td class="vtop"><p class="cap_center"><span class="smcap">Fig. 15.</span> <i>Biloculina.</i></p> - <p class="cap_center2">A many-chambered Foraminifer.<br />Magnified as a transparent object.</p></td> -</tr> -<tr> - <td class="center" style="width:200px"><img src="images/fig_16.png" width="187" height="160" alt="" /></td> - <td class="center" style="width:200px"><img src="images/fig_17.png" width="224" height="181" alt="" /></td> -</tr> -<tr> - <td class="vtop"><p class="cap_center"><span class="smcap">Fig. 16.</span> <i>Polystomella.</i></p> - <p class="cap_center2">A spiral Foraminifer.<br />Magnified as an opaque object.</p></td> - <td class="vtop"><p class="cap_center"><span class="smcap">Fig. 17.</span> <i>Polymorphina.</i></p> - <p class="cap_center2">A many-chambered Foraminifer. Magnified as an opaque object. Figs. 14 to - 17 are from original sketches of Post-pliocene specimens.</p></td> -</tr> -</table> -</div> - -<p><span class="pagenum"><a name="Page_63" id="Page_63">« 63 »</a></span></p> - -<p>The Amœba 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 -addition multitudes of microscopic pores through which -the soft gelatinous matter can ooze, and form outside -finger-like or thread-like extensions for collecting food. -In some cases the shell consists of a single cavity only, -but in most, after one cell is completed, others are added, -forming a series of cells or chambers communicating -with each other, and often arranged spirally or otherwise -in most beautiful and symmetrical forms. Some -of these creatures, usually named Foraminifera, are -locomotive, others sessile and attached. Most of them -are microscopic, but some grow by multiplication of -chambers till they are a quarter of an inch or more in -breadth. (<a href="#fig_14">Figs. 14 to 17.</a>)</p> - -<p>The original skeleton or primary cell-wall of most of -these creatures is seen under the microscope to be perforated -with innumerable pores, and is extremely thin. -When, however, owing to the increased size of the -shell, or other wants of the creature, it is necessary to -<span class="pagenum"><a name="Page_64" id="Page_64">« 64 »</a></span> -give strength, this is done by adding new portions of -carbonate of lime to the outside, and to these Dr. Carpenter -has given the appropriate name of “supplemental -skeleton;” and this, when covered by new growths, -becomes what he has termed an “intermediate skeleton.” -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. (<a href="#fig_20">Fig. 20.</a>) Thus there are microscopic -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 accumulation -takes place we learn from what is now going on -in the ocean, more especially from the result of the -recent deep-sea dredging expeditions. The Foraminifera -are vastly numerous, both near the 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 hardened -into limestone. This process is now depositing a -great thickness of white ooze in the bottom of the -ocean; and in times past it has produced such vast -thicknesses of calcareous matter as the chalk and -the nummulitic limestone of Europe and the orbitoidal -<span class="pagenum"><a name="Page_65" id="Page_65">« 65 »</a></span> -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.</p> - -<p>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 meantime -we shall see what claims Eozoon has to be included -among them.</p> - -<p>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 crystalline -marble, the cavities of the cells by green serpentine, -the mode of whose introduction we shall have to -consider in the sequel. The lowest layer of 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 -<span class="pagenum"><a name="Page_66" id="Page_66">« 66 »</a></span> -Huxley the name <i>Bathybius</i>, 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, perforated -by innumerable minute tubuli, and by some -larger pores or septal orifices, while supported at intervals -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. (<a href="#fig_10">Fig. 10.</a>) 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 successive -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, -<a href="#Plate_III">Plate III.</a>, and nature print, <a href="#Plate_V">Plate. V.</a>) 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” -<span class="pagenum"><a name="Page_67" id="Page_67">« 67 »</a></span> -manner, and with very thin walls unprotected by supplemental -skeleton. Then the growth was arrested, -and possibly these upper layers gave off reproductive -germs, fitted to float or swim away and to establish -new colonies. We may have such reproductive germs -in certain curious globular bodies, like loose cells, found -in connection with irregular Eozoon in one of the -Laurentian limestones at Long Lake and elsewhere. -These curious organisms I observed some years ago, -but no description of them was published at the time, -as I hoped to obtain better examples. I now figure -some of them, and give their description in a note. -(Fig. 18). I have recently obtained numerous additional -<span class="pagenum"><a name="Page_68" id="Page_68">« 68 »</a></span> -examples from the beds holding Eozoon at St. Pierre, -on the Ottawa. They occur at this place on the surface -of layers of the limestone in vast numbers, as if -they had been growing separately on the bottom, or -had been drifted over it by currents. These we shall -further discuss hereafter. Such was the general mode -of growth of Eozoon, and we may now consider more in -detail some questions as to its gigantic size, its precise -mode of nutrition, the arrangement of its parts, its relations -to more modern forms, and the effects of its growth -in the Laurentian seas. In the meantime a study of -our illustration, <a href="#Plate_IV">Plate. IV.</a>, which is intended as a magnified -restoration of the animal, will enable the reader -distinctly to understand its structure and probable -mode of growth, and to avail himself intelligently of -the partial representations of its fossilized remains in -the other plates and woodcuts.</p> - -<div class="fig_center" style="width: 271px;"> -<a name="fig_18" id="fig_18"></a> -<img src="images/fig_18.png" width="271" height="289" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 18.</span> <i>Minute Foraminiferal forms from the Laurentian of Long -Lake.</i></p> - -<p class="cap_center2">Highly magnified. (<i>a.</i>) Single cell, showing tubulated wall. (<i>b, c.</i>) Portions of -same more highly magnified. (<i>d.</i>) Serpentine cast of a similar chamber, -decalcified, and showing casts of tubuli.</p> -</div> - -<p>With respect to its size, we shall find in a subsequent -chapter that this was rivalled by some succeeding -animals of the same humble type in the Silurian age; -and that, as a whole, foraminiferal animals have been -diminishing in size in the lapse of geological time. It -is indeed a fact of so frequent occurrence that it may -almost be regarded as a law of the introduction of new -forms of life, that they assume in their early history -gigantic dimensions, and are afterwards continued by -less magnificent species. The relations of this to external -conditions, in the case of higher animals, are often -complex and difficult to understand; but in organisms -so low as Eozoon and its allies, they lie more on the -<span class="pagenum"><a name="Page_69" id="Page_69">« 69 »</a></span> -surface. Such creatures may be regarded as the -simplest and most ready media for the conversion of -vegetable matter into animal tissues, and their functions -are almost entirely limited to those of nutrition. Hence -it is likely that they will be able to appear in the most -gigantic forms under such conditions as afford them -the greatest amount of pabulum for the nourishment -of their soft parts and for their skeletons. There is -reason to believe, for example, that the occurrence, both -in the chalk and the deep-sea mud, of immense quantities -of the minute bodies known as Coccoliths along with -Foraminifera, is not accidental. The Coccoliths appear -to be grains of calcareous matter formed in minute -plants adapted to a deep-sea habitat; and these, along -with the vegetable and animal debris constantly being -derived from the death of the living things at the surface, -afford the material both of sarcode and shell. -Now if the Laurentian graphite represents an exuberance -of vegetable growth in those old seas proportionate -to the great supplies of carbonic acid in the atmosphere -and in the waters, and if the Eozoic ocean was even -better supplied with carbonate of lime than those -Silurian seas whose vast limestones bear testimony to -their richness in such material, we can easily imagine -that the conditions may have been more favourable to -a creature like Eozoon than those of any other period -of geological time.</p> - -<p>Growing, as Eozoon did, on the floor of the ocean, and -covering wide patches with more or less irregular -masses, it must have thrown up from its whole surface -<span class="pagenum"><a name="Page_70" id="Page_70">« 70 »</a></span> -its pseudopods to seize whatever floating particles of -food the waters carried over it. There is also reason -to believe, from the outline of certain specimens, that it -often grew upward in cylindrical or club-shaped forms, -and that the broader patches were penetrated by large -pits or oscula, admitting the sea-water deeply into the -substance of the masses. In this way its growth -might be rapid and continuous; but it does not seem -to have possessed the power of growing indefinitely by -new and living layers covering those that had died, in -the manner of some corals. Its life seems to have had -a definite termination, and when that was reached an -entirely new colony had to be commenced. In this it -had more affinity with the Foraminifera, as we now -know them, than with the corals, though practically it -had the same power with the coral polyps of accumulating -limestone in the sea bottom, a power indeed still -possessed by its foraminiferal successors. In the -case of coral limestones, we know that a large proportion -of these consist not of continuous reefs but of -fragments of coral mixed with other calcareous organisms, -spread usually by waves and currents in continuous -beds over the sea bottom. In like manner we -find in the limestones containing Eozoon, layers of fragmental -matter which shows in places the characteristic -structures, and which evidently represents the debris -swept from the Eozoic masses and reefs by the action of -the waves. It is with this fragmental matter that the -small rounded organisms already referred to most frequently -occur; and while they may be distinct -<span class="pagenum"><a name="Page_71" id="Page_71">« 71 »</a></span> -animals, they may also be the fry of Eozoon, or small -portions of its acervuline upper surface floated off in a -living state, and possibly capable of living independently -and of founding new colonies.</p> - -<p>It is only by a somewhat wild poetical licence that -Eozoon has been represented as a “kind of enormous -composite animal stretching from the shores of Labrador -to Lake Superior, and thence northward and southward -to an unknown distance, and forming masses -1500 feet in depth.” We may discuss by-and-by the -question of the composite nature of masses of Eozoon, -and we see in the corals evidence of the great size to -which composite animals of a higher grade can attain. -In the case of Eozoon we must imagine an ocean floor -more uniform and level than that now existing. On -this the organism would establish itself in spots and -patches. These might finally become confluent over -large areas, just as massive corals do. As individual -masses attained maturity and died, their pores would be -filled up with limestone or silicious deposits, and thus -could form a solid basis for new generations, and in -this way limestone to an indefinite extent might be -produced. Further, wherever such masses were high -enough to be attacked by the breakers, or where portions -of the sea bottom were elevated, the more fragile -parts of the surface would be broken up and scattered -widely in beds of fragments over the bottom of the sea, -while here and there beds of mud or sand or of volcanic -debris would be deposited over the living or dead -organic mass, and would form the layers of gneiss -<span class="pagenum"><a name="Page_72" id="Page_72">« 72 »</a></span> -and other schistose rocks interstratified with the -Laurentian limestone. In this way, in short, Eozoon -would perform a function combining that which corals -and Foraminifera perform in the modern seas; forming -both reef limestones and extensive chalky beds, and -probably living both in the shallow and the deeper -parts of the ocean. If in connection with this we consider -the rapidity with which the soft, simple, and -almost structureless sarcode of these Protozoa can be -built up, and the probability that they were more -abundantly supplied with food, both for nourishing their -soft parts and skeletons, than any similar creatures in -later times, we can readily understand the great -volume and extent of the Laurentian limestones which -they aided in producing. I say aided in producing, -because I would not desire to commit myself to the -doctrine that the Laurentian limestones are wholly of -this origin. There may have been other animal limestone-builders -than Eozoon, and there may have been -limestones formed by plants like the modern Nullipores -or by merely mineral deposition.</p> - -<p><span class="pagenum"><a name="Page_73" id="Page_73">« 73 »</a></span></p> - -<div class="fig_center" style="width: 298px;"> -<a name="fig_19" id="fig_19"></a> -<img src="images/fig_19.png" width="298" height="157" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 19.</span> <i>Section of a Nummulite, from Eocene Limestone of Syria.</i></p> - -<p class="cap_center2">Showing chambers, tubuli, and canals. Compare this and <a href="#fig_20">fig. 20</a> with figs. 10 -and 11.</p> -</div> - -<div class="fig_center" style="width: 326px;"> -<a name="fig_20" id="fig_20"></a> -<img src="images/fig_20.png" width="326" height="268" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 20.</span> <i>Portion of shell of Calcarina.</i></p> - -<p class="cap_center2">Magnified, after Carpenter. (<i>a.</i>) Cells. (<i>b.</i>) Original cell-wall with tubuli. (<i>c.</i>) -Supplementary skeleton with canals.</p> -</div> - -<p>Its relations to modern animals of its type have been -very clearly defined by Dr. Carpenter. In the structure -of its proper wall and its fine parallel perforations, it -resembles the <i>Nummulites</i> and their allies; and the -organism may therefore be regarded as an aberrant -member of the Nummuline group, which affords some -of the largest and most widely distributed of the fossil -Foraminifera. This resemblance may be seen in <a href="#fig_19">fig. 19</a>. -To the Nummulites it also conforms in its -tendency to form a supplemental or intermediate skeleton -with canals, though the canals themselves in their -arrangement more nearly resemble Calcarina, which -is represented in <a href="#fig_20">fig. 20</a>. In its superposition of many -layers, and in its tendency to a heaped up or acervuline -irregular growth it resembles <i>Polytrema</i> and <i>Tinoporus</i>, -<span class="pagenum"><a name="Page_74" id="Page_74">« 74 »</a></span> -forms of a different group in so far as shell-structure is -concerned. It may thus be regarded as a composite -type, combining peculiarities now observed in two -groups, or it may be regarded as a representative in the -Nummuline series of Polytrema and Tinoporus in the -Rotaline series. At the time when Dr. Carpenter stated -these affinities, it might be objected that Foraminifera -of these families are in the main found in the Modern -and Tertiary periods. Dr. Carpenter has since shown -that the curious oval Foraminifer called <i>Fusulina</i>, found -in the coal formation, is in like manner allied to both -Nummulites and Rotalines; and still more recently -Mr. Brady has discovered a true Nummulite in the -Lower Carboniferous of Belgium. This group being -now fairly brought down to the Palæozoic, we may hope -finally to trace it back to the Primordial, and thus to -bring it still nearer to Eozoon in time.</p> - -<div class="fig_center" style="width: 374px;"> -<a name="fig_21" id="fig_21"></a> -<img src="images/fig_21.png" width="374" height="319" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 21.</span> <i>Foraminiferal Rock Builders.</i></p> - -<p class="cap_center2">(<i>a.</i>) Nummulites lævigata—Eocene. (<i>b.</i>) The same, showing chambered interior. -(<i>c.</i>) Milioline limestone, magnified—Eocene, Paris. (<i>d.</i>) Hard -Chalk, section magnified—Cretaceous.</p> -</div> - -<p>Though Eozoon was probably not the only animal of -the Laurentian seas, yet it was in all likelihood the -most conspicuous and important as a collector of calcareous -matter, filling the same place afterwards -occupied by the reef-building corals. Though probably -less efficient than these as a constructor of solid -limestones, from its less permanent and continuous -growth, it formed wide floors and patches on the sea-bottom, -and when these were broken up vast quantities -of limestone were formed from their debris. It must -also be borne in mind that Eozoon was not everywhere -infiltrated with serpentine or other silicious minerals; -quantities of its substance were merely filled with carbonate -<span class="pagenum"><a name="Page_75" id="Page_75">« 75 »</a></span> -of lime, resembling the chamber-wall so closely -that it is nearly impossible to make out the difference, -and thus is likely to pass altogether unobserved -by collectors, and to baffle even the microscopist. -(<a href="#fig_24">Fig. 24.</a>) Although therefore the layers which contain -well characterized Eozoon are few and far between, -there is reason to believe that in the composition of the -limestones of the Laurentian it bore no small part, and -as these limestones are some of them several hundreds -of feet in thickness, and extend over vast areas, Eozoon -may be supposed to have been as efficient a world-builder -as the Stromatoporæ of the Silurian and -<span class="pagenum"><a name="Page_76" id="Page_76">« 76 »</a></span> -Devonian, the Globigerinæ and their allies in the chalk, -or the Nummulites and Miliolites in the Eocene. The -two latter groups of rock-makers are represented in -our cut, <a href="#fig_21">fig. 21</a>; the first will engage our attention in -chapter sixth. It is a remarkable illustration of the -constancy of natural causes and of the persistence of -animal types, that these humble Protozoans, which began -to secrete calcareous matter in the Laurentian -period, have been continuing their work in the ocean -through all the geological ages, and are still busy in -accumulating those chalky muds with which recent -dredging operations in the deep sea have made us so -familiar.</p> - - -<hr class="r20" /> - -<p class="caption2">NOTES TO CHAPTER IV.</p> - - -<p class="center">(A.) <span class="smcap">Original Description of Eozoon Canadense.</span></p> - -<p class="center smaller">[As given by the author in the <i>Journal of the Geological Society</i>, -February, 1865.]</p> - -<div class="blockquot"> - -<p>"At the request of Sir W. E. Logan, I have submitted to -microscopic examination slices of certain peculiar laminated -forms, consisting of alternate layers of carbonate of lime and -serpentine, and of carbonate of lime and white pyroxene, -found in the Laurentian limestone of Canada, and regarded by -Sir William as possibly fossils. I have also examined slices -of a large number of limestones from the Laurentian series, -not showing the forms of these supposed fossils.</p> - -<p>"The specimens first mentioned are masses, often several -inches in diameter, presenting to the naked eye alternate -laminæ of serpentine, or of pyroxene, and carbonate of lime. -Their general aspect, as remarked by Sir W. E. Logan -(<i>Geology of Canada</i>, 1863, p. 49), reminds the observer of that -of the Silurian corals of the genus Stromatopora, except that -<span class="pagenum"><a name="Page_77" id="Page_77">« 77 »</a></span> -the laminæ diverge from and approach each other, and frequently -anastomose or are connected by transverse septa.</p> - -<p>"Under the microscope the resemblance to Stromatopora is -seen to be in general form merely, and no trace appears of the -radiating pillars characteristic of that genus. The laminæ of -serpentine and pyroxene present no organic structure, and the -latter mineral is highly crystalline. The laminæ of carbonate -of lime, on the contrary, retain distinct traces of structures -which cannot be of a crystalline or concretionary character. -They constitute parallel or concentric partitions of variable -thickness, enclosing flattened spaces or chambers, frequently -crossed by transverse plates or septa, in some places so -numerous as to give a vesicular appearance, in others occurring -only at rare intervals. The laminæ themselves are -excavated on their sides into rounded pits, and are in some -places traversed by canals, or contain secondary rounded cells, -apparently isolated. In addition to these general appearances, -the substance of the laminæ, where most perfectly preserved, -is seen to present a fine granular structure, and to be penetrated -by numerous minute tubuli, which are arranged in -bundles of great beauty and complexity, diverging in sheaf-like -forms, and in their finer extensions anastomosing so as to -form a network (figs. 10 and 28). In transverse sections, -and under high powers, the tubuli are seen to be circular -in outline, and sharply defined (<a href="#fig_29">fig. 29</a>). In longitudinal -sections, they sometimes present a beaded or jointed appearance. -Even where the tubular structure is least perfectly -preserved, traces of it can still be seen in most of the slices, -though there are places in which the laminæ are perfectly -compact, and perhaps were so originally.</p> - -<p>"With respect to the nature and probable origin of the -appearances above described, I would make the following -remarks:—</p> - -<p>"1. The serpentine and pyroxene which fill the cavities of -the calcareous matter have no appearance of concretionary -structure. On the contrary, their aspect is that of matter -introduced by infiltration, or as sediment, and filling spaces -previously existing. In other words, the calcareous matter -<span class="pagenum"><a name="Page_78" id="Page_78">« 78 »</a></span> -has not been moulded on the forms of the serpentine and -augite, but these have filled spaces or chambers in a hard calcareous -mass. This conclusion is further confirmed by the -fact, to be referred to in the sequel, that the serpentine includes -multitudes of minute foreign bodies, while the calcareous -matter is uniform and homogeneous. It is also to be -observed that small veins of carbonate of lime occasionally -traverse the specimen’s, and in their entire absence of structures -other than crystalline, present a striking contrast to the -supposed fossils.</p> - -<p>"2. Though the calcareous laminæ have in places a crystalline -cleavage, their forms and structures have no relation to -this. Their cells and canals are rounded, and have smooth -walls, which are occasionally lined with films apparently of -carbonaceous matter. Above all, the minute tubuli are -different from anything likely to occur in merely crystalline -calc-spar. While in such rocks little importance might be -attached to external forms simulating the appearances of -corals, sponges, or other organisms, these delicate internal -structures have a much higher claim to attention. Nor is -there any improbability in the preservation of such minute -parts in rocks so highly crystalline, since it is a circumstance -of frequent occurrence in the microscopic examination of -fossils that the finest structures are visible in specimens in -which the general form and the arrangement of parts have -been obliterated. It is also to be observed that the structure -of the calcareous laminæ is the same, whether the intervening -spaces are filled with serpentine or with pyroxene.</p> - -<p>"3. The structures above described are not merely definite -and uniform, but they are of a kind proper to animal organisms, -and more especially to one particular type of animal -life, as likely as any other to occur under such circumstances: -I refer to that of the Rhizopods of the order Foraminifera. -The most important point of difference is in the great size and -compact habit of growth of the specimens in question; but -there seems no good reason to maintain that Foraminifera -must necessarily be of small size, more especially since forms -of considerable magnitude referred to this type are known in -<span class="pagenum"><a name="Page_79" id="Page_79">« 79 »</a></span> -the Lower Silurian. Professor Hall has described specimens -of Receptaculites twelve inches in diameter; and the fossils -from the Potsdam formation of Labrador, referred by Mr. -Billings to the genus Archæocyathus, are examples of Protozoa -with calcareous skeletons scarcely inferior in their massive -style of growth to the forms now under consideration.</p> - -<p>"These reasons are, I think, sufficient to justify me in regarding -these remarkable structures as truly organic, and -in searching for their nearest allies among the Foraminifera.</p> - -<p>"Supposing then that the spaces between the calcareous -laminæ, as well as the canals and tubuli traversing their substance, -were once filled with the sarcode body of a Rhizopod, -comparisons with modern forms at once suggest themselves.</p> - -<p>"From the polished specimens in the Museum of the -Canadian Geological Survey, it appears certain that these -bodies were sessile by a broad base, and grew by the addition -of successive layers of chambers separated by calcareous -laminæ, but communicating with each other by canals or -septal orifices sparsely and irregularly distributed. Small -specimens have thus much the aspect of the modern genera -Carpenteria and Polytrema. Like the first of these genera, -there would also seem to have been a tendency to leave in -the midst of the structure a large central canal, or deep -funnel-shaped or cylindrical opening, for communication with -the sea-water. Where the laminæ coalesce, and the structure -becomes more vesicular, it assumes the ‘acervuline’ character -seen in such modern forms as Nubecularia.</p> - -<p>"Still the magnitude of these fossils is enormous when -compared with the species of the genera above named; and -from the specimens in the larger slabs from Grenville, in -the museum of the Canadian Survey, it would seem that these -organisms grew in groups, which ultimately coalesced, and -formed large masses penetrated by deep irregular canals; -and that they continued to grow at the surface, while the -lower parts became dead and were filled up with infiltrated -matter or sediment. In short, we have to imagine an organism -having the habit of growth of Carpenteria, but attaining -<span class="pagenum"><a name="Page_80" id="Page_80">« 80 »</a></span> -to an enormous size, and by the aggregation of individuals -assuming the aspect of a coral reef.</p> - -<p>"The complicated systems of tubuli in the Laurentian fossil -indicate, however, a more complex structure than that of any -of the forms mentioned above. I have carefully compared -these with the similar structures in the ‘supplementary -skeleton’ (or the shell-substance that carries the vascular -system) of Calcarina and other forms, and can detect no -difference except in the somewhat coarser texture of the tubuli -in the Laurentian specimens. It accords well with the great -dimensions of these, that they should thus thicken their walls -with an extensive deposit of tubulated calcareous matter; and -from the frequency of the bundles of tubuli, as well as from -the thickness of the partitions, I have no doubt that all the -successive walls, as they were formed, were thickened in this -manner, just as in so many of the higher genera of more -modern Foraminifera.</p> - -<p>"It is proper to add that no spicules, or other structures -indicating affinity to the Sponges, have been detected in any -of the specimens.</p> - -<p>“As it is convenient to have a name to designate these -forms, I would propose that of Eozoon, which will be specially -appropriate to what seems to be the characteristic fossil of a -group of rocks which must now be named Eozoic rather than -Azoic. For the species above described, the specific name of -Canadense has been proposed. It may be distinguished by -the following characters:—</p> - -<p>“<span class="smcap">Eozoon Canadense</span>; <i>gen. et spec. nov.</i></p> - -<p>“<i>General form.</i>—Massive, in large sessile patches or irregular -cylinders, growing at the surface by the addition of -successive laminæ.</p> - -<p>“<i>Internal structure.</i>—Chambers large, flattened, irregular, -with numerous rounded extensions, and separated by walls of -variable thickness, which are penetrated by septal orifices -irregularly disposed. Thicker parts of the walls with bundles -of fine branching tubuli.</p> - -<p>“These characters refer specially to the specimens from -Grenville and the Calumet. There are others from Perth, -<span class="pagenum"><a name="Page_81" id="Page_81">« 81 »</a></span> -C. W., which show more regular laminæ, and in which the -tubuli have not yet been observed; and a specimen from -Burgess, C. W., contains some fragments of laminæ which -exhibit, on one side, a series of fine parallel tubuli like those -of Nummulina. These specimens may indicate distinct -species; but on the other hand, their peculiarities may depend -on different states of preservation.</p> - -<p>“With respect to this last point, it may be remarked that -some of the specimens from Grenville and the Calumet show -the structure of the laminæ with nearly equal distinctness, -whether the chambers are filled with serpentine or pyroxene, -and that even the minute tubuli are penetrated and filled with -these minerals. On the other hand, there are large specimens -in the collection of the Canadian Survey in which the lower -and still parts of the organism are imperfectly preserved in -pyroxene, while the upper parts are more perfectly mineralized -with serpentine.”</p> - -<hr class="tb" /> - -<p>[The following note was added in a reprint of the paper in -the <i>Canadian Naturalist</i>, April, 1865.]</p> - -<p>“Since the above was written, thick slices of Eozoon from -Grenville have been prepared, and submitted to the action of -hydrochloric acid until the carbonate of lime was removed. -The serpentine then remains as a cast of the interior of the -chambers, showing the form of their original sarcode-contents. -The minute tubuli are found also to have been filled with a -substance insoluble in the acid, so that casts of these also -remain in great perfection, and allow their general distribution -to be much better seen than in the transparent slices -previously prepared. These interesting preparations establish -the following additional structural points:—</p> - -<p>“1. That the whole mass of sarcode throughout the organism -was continuous; the apparently detached secondary -chambers being, as I had previously suspected, connected -with the larger chambers by canals filled with sarcode.</p> - -<p>“2. That some of the irregular portions without lamination -are not fragmentary, but due to the acervuline growth of the -animal; and that this irregularity has been produced in part -<span class="pagenum"><a name="Page_82" id="Page_82">« 82 »</a></span> -by the formation of projecting patches of supplementary -skeleton, penetrated by beautiful systems of tubuli. These -groups of tubuli are in some places very regular, and have in -their axes cylinders of compact calcareous matter. Some -parts of the specimens present arrangements of this kind as -symmetrical as in any modern Foraminiferal shell.</p> - -<p>“3. That all except the very thinnest portions of the walls -of the chambers present traces, more or less distinct, of a -tubular structure.</p> - -<p>“4. These facts place in more strong contrast the structure -of the regularly laminated species from Burgess, which do not -show tubuli, and that of the Grenville specimens, less regularly -laminated and tubulous throughout. I hesitated however to -regard these two as distinct species, in consequence of the -intermediate characters presented by specimens from the -Calumet, which are regularly laminated like those of Burgess, -and tubulous like those of Grenville. It is possible that in -the Burgess specimens, tubuli, originally present, have been -obliterated, and in organisms of this grade, more or less -altered by the processes of fossilisation, large series of specimens -should be compared before attempting to establish -specific distinctions.”</p> -</div> - - -<p class="center">(B.) <span class="smcap">Original Description of the Specimens added by -Dr. Carpenter to the above—in a Letter to -Sir W. E. Logan.</span></p> - -<p class="center smaller">[<i>Journal of Geological Society</i>, February, 1865.]</p> - -<div class="blockquot"> - -<p>"The careful examination which I have made, in accordance -with the request you were good enough to convey to me from -Dr. Dawson and to second on your own part, with the structure -of the very extraordinary fossil which you have brought -from the Laurentian rocks of Canada,<a name="FNanchor_17" id="FNanchor_17"></a><a href="#Footnote_17" class="fnanchor">[Q]</a> enables me most<span class="pagenum"><a name="Page_83" id="Page_83">« 83 »</a></span> -unhesitatingly to confirm the sagacious determination of -Dr. Dawson as to its Rhizopod characters and Foraminiferal -affinities, and at the same time furnishes new evidence of no -small value in support of that determination. In this examination -I have had the advantage of a series of sections of the -fossil much superior to those submitted to Dr. Dawson; and -also of a large series of decalcified specimens, of which -Dr. Dawson had only the opportunity of seeing a few examples -after his memoir had been written. These last are -peculiarly instructive; since in consequence of the complete -infiltration of the chambers and canals, originally occupied by -the sarcode-body of the animal, by mineral matter insoluble in -dilute nitric acid, the removal of the calcareous shell brings -into view, not only the internal casts of the chambers, but also -casts of the interior of the ‘canal system’ of the ‘intermediate’ -or ‘supplemental skeleton,’ and even casts of the interior of -the very fine parallel tubuli which traverse the proper walls of -the chambers. And, as I have remarked elsewhere,<a name="FNanchor_18" id="FNanchor_18"></a><a href="#Footnote_18" class="fnanchor">[R]</a> ‘such -casts place before us far more exact representations of the -configuration of the animal body, and of the connections of its -different parts, than we could obtain even from living specimens -by dissolving away their shells with acid; its several -portions being disposed to heap themselves together in a mass -when they lose the support of the calcareous skeleton.’</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_17" id="Footnote_17"></a><a href="#FNanchor_17"><span class="label">[Q]</span></a> The specimens submitted to Dr. Carpenter were taken from a -block of Eozoon rock, obtained in the Petite Nation seigniory, too -late to afford Dr. Dawson an opportunity of examination. They are -from the same horizon as the Grenville specimens.—W. E. L.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_18" id="Footnote_18"></a><a href="#FNanchor_18"><span class="label">[R]</span></a> <i>Introduction to the Study of the Foraminifera</i>, p. 10.</p> -</div> -<p><span class="pagenum"><a name="Page_84" id="Page_84">« 84 »</a></span></p> -<div class="blockquot"> - -<p>"The additional opportunities I have thus enjoyed will be -found, I believe, to account satisfactorily for the differences to -be observed between Dr. Dawson’s account of the Eozoon and -my own. Had I been obliged to form my conclusions respecting -its structure only from the specimens submitted to Dr. -Dawson, I should very probably have seen no reason for any -but the most complete accordance with his description: while -if Dr. Dawson had enjoyed the advantage of examining the -entire series of preparations which have come under my -own observation, I feel confident that he would have anticipated -the corrections and additions which I now offer.</p> - -<p>"Although the general plan of growth described by Dr. -Dawson, and exhibited in his photographs of vertical sections of -the fossil, is undoubtedly that which is typical of Eozoon, yet -I find that the acervuline mode of growth, also mentioned by -Dr. Dawson, very frequently takes its place in the more -superficial parts, where the chambers, which are arranged in -regular tiers in the laminated portions, are heaped one upon -another without any regularity, as is particularly well shown -in some decalcified specimens which I have myself prepared -from the slices last put into my hands. I see no indication -that this departure from the normal type of structure has -resulted from an injury; the transition from the regular to -the irregular mode of increase not being abrupt but gradual. -Nor shall I be disposed to regard it as a monstrosity; since -there are many other Foraminifera in which an originally definite -plan of growth gives place, in a later stage, to a like -acervuline piling-up of chambers.</p> - -<p>"In regard to the form and relations of the chambers, I have -little to add to Dr. Dawson’s description. The evidence -afforded by their internal casts concurs with that of sections, -in showing that the segments of the sarcode-body, by whose -aggregation each layer was constituted, were but very incompletely -divided by shelly partitions; this incomplete separation -(as Dr. Dawson has pointed out) having its parallel in that of -the secondary chambers in Carpenteria. But I have occasionally -met with instances in which the separation of the chambers -has been as complete as it is in Foraminifera generally; and -the communication between them is then established by several -narrow passages exactly corresponding with those which I -have described and figured in Cycloclypeus.<a name="FNanchor_19" id="FNanchor_19"></a><a href="#Footnote_19" class="fnanchor">[S]</a></p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_19" id="Footnote_19"></a><a href="#FNanchor_19"><span class="label">[S]</span></a> <i>Op. cit.</i>, p. 294.</p> -</div> - - -<div class="blockquot"> - -<p>"The mode in which each successive layer originates from -the one which had preceded it, is a question to which my attention -has been a good deal directed; but I do not as yet feel -confident that I have been able to elucidate it completely. -There is certainly no regular system of apertures for the -passage of stolons giving origin to new segments, such as are -found in all ordinary Polythalamous Foraminifera, whether -their type of growth be rectilinear, spiral, or cyclical; and I -am disposed to believe that where one layer is separated from -<span class="pagenum"><a name="Page_85" id="Page_85">« 85 »</a></span> -another by nothing else than the proper walls of the chambers,—which, -as I shall presently show, are traversed by multitudes -of minute tubuli giving passage to pseudopodia,—the -coalescence of these pseudopodia on the external surface would -suffice to lay the foundation of a new layer of sarcodic segments. -But where an intermediate or supplemental skeleton, -consisting of a thick layer of solid calcareous shell, has been -deposited between two successive layers, it is obvious that -the animal body contained in the lower layer of chambers -must be completely cut off from that which occupies the -upper, unless some special provision exist for their mutual -communication. Such a provision I believe to have been -made by the extension of bands of sarcode, through canals left -in the intermediate skeleton, from the lower to the upper tier -of chambers. For in such sections as happen to have traversed -thick deposits of the intermediate skeleton, there are -generally found passages distinguished from those of the -ordinary canal-system by their broad flat form, their great -transverse diameter, and their non-ramification. One of these -passages I have distinctly traced to a chamber, with the cavity -of which it communicated through two or three apertures in -its proper wall; and I think it likely that I should have been -able to trace it at its other extremity into a chamber of the -superjacent tier, had not the plane of the section passed out of -its course. Riband-like casts of these passages are often to -be seen in decalcified specimens, traversing the void spaces -left by the removal of the thickest layers of the intermediate -skeleton.</p> - -<p>"But the organization of a new layer seems to have not unfrequently -taken place in a much more considerable extension -of the sarcode-body of the pre-formed layer; which either -folded back its margin over the surface already consolidated, -in a manner somewhat like that in which the mantle of a -Cyprœa doubles back to deposit the final surface-layer of its -shell, or sent upwards wall-like lamellæ, sometimes of very -limited extent, but not unfrequently of considerable length, -which, after traversing the substance of the shell, like trap-dykes -in a bed of sandstone, spread themselves out over its -<span class="pagenum"><a name="Page_86" id="Page_86">« 86 »</a></span> -surface. Such, at least, are the only interpretations I can put -upon the appearances presented by decalcified specimens. -For on the one hand, it is frequently to be observed that two -bands of serpentine (or other infiltrated mineral), which represent -two layers of the original sarcode-body of the animal, -approximate to each other in some part of their course, and -come into complete continuity; so that the upper layer would -seem at that part to have had its origin in the lower. Again, -even where these bands are most widely separated, we find -that they are commonly held together by vertical lamellæ of -the same material, sometimes forming mere tongues, but often -running to a considerable length. That these lamellæ have -not been formed by mineral infiltration into accidental fissures -in the shell, but represent corresponding extensions of the -sarcode-body, seems to me to be indicated not merely by the -characters of their surface, but also by the fact that portions -of the canal-system may be occasionally traced into connection -with them.</p> - -<p>"Although Dr. Dawson has noticed that some parts of the -sections which he examined present the fine tubulation characteristic -of the shells of the Nummuline Foraminifera, he does -not seem to have recognised the fact, which the sections -placed in my hands have enabled me most satisfactorily to -determine,—that the proper walls of the chambers everywhere -present the fine tubulation of the Nummuline shell; a -point of the highest importance in the determination of the -affinities of Eozoon. This tubulation, although not seen with -the clearness with which it is to be discerned in recent examples -of the Nummuline type, is here far better displayed than -it is in the majority of fossil Nummulites, in which the tubuli -have been filled up by the infiltration of calcareous matter, -rendering the shell-substance nearly homogeneous. In Eozoon -these tubuli have been filled up by the infiltration of a mineral -different from that of which the shell is composed, and therefore -not coalescing with it; and the tubular structure is consequently -much more satisfactorily distinguishable. In decalcified -specimens, the free margins of the casts of the -chambers are often seen to be bordered with a delicate white -<span class="pagenum"><a name="Page_87" id="Page_87">« 87 »</a></span> -glistening fringe; and when this fringe is examined with a -sufficient magnifying power, it is seen to be made up of a -multitude of extremely delicate aciculi, standing side by side -like the fibres of asbestos. These, it is obvious, are the internal -casts of the fine tubuli which perforated the proper wall of -the chambers, passing directly from its inner to its outer -surface; and their presence in this situation affords the most -satisfactory confirmation of the evidence of that tubulation -afforded by thin sections of the shell-wall.</p> - -<p>"The successive layers, each having its own proper wall, are -often superposed one upon another without the intervention of -any supplemental or intermediate skeleton such as presents -itself in all the more massive forms of the Nummuline series; -but a deposit of this form of shell-substance, readily distinguishable -by its homogeneousness from the finely tubular -shell immediately investing the segments of the sarcode-body, -is the source of the great thickening which the calcareous -zones often present in vertical sections of Eozoon. The presence -of this intermediate skeleton has been correctly indicated -by Dr. Dawson; but he does not seem to have clearly -differentiated it from the proper wall of the chambers. All -the tubuli which he has described belong to that canal system -which, as I have shown,<a name="FNanchor_20" id="FNanchor_20"></a><a href="#Footnote_20" class="fnanchor">[T]</a> is limited in its distribution to the -intermediate skeleton, and is expressly designed to supply a -channel for its nutrition and augmentation. Of this canal -system, which presents most remarkable varieties in dimensions -and distribution, we learn more from the casts presented -by decalcified specimens, than from sections, which only -exhibit such parts of it as their plane may happen to traverse. -Illustrations from both sources, giving a more complete -representation of it than Dr. Dawson’s figures afford, have -been prepared from the additional specimens placed in my -hands.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_20" id="Footnote_20"></a><a href="#FNanchor_20"><span class="label">[T]</span></a> <i>Op. cit.</i>, <a href="#Page_50">pp. 50, 51</a>.</p> -</div> - -<p><span class="pagenum"><a name="Page_88" id="Page_88">« 88 »</a></span></p> - -<div class="blockquot"> - -<p>"It does not appear to me that the canal system takes its -origin directly from the cavity of the chambers. On the contrary, -I believe that, as in Calcarina (which Dr. Dawson has -correctly referred to as presenting the nearest parallel to it -among recent Foraminifera), they originate in lacunar spaces -on the outside of the proper walls of the chambers, into which -the tubuli of those walls open externally; and that the extensions -of the sarcode-body which occupied them were formed -by the coalescence of the pseudopodia issuing from those -tubuli.<a name="FNanchor_21" id="FNanchor_21"></a><a href="#Footnote_21" class="fnanchor">[U]</a></p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_21" id="Footnote_21"></a><a href="#FNanchor_21"><span class="label">[U]</span></a> <i>Op. cit.</i>, <a href="#Page_221">p. 221</a>.</p> -</div> - -<div class="blockquot"> - -<p>"It seems to me worthy of special notice, that the canal -system, wherever displayed in transparent sections, is distinguished -by a yellowish brown coloration, so exactly resembling -that which I have observed in the canal system of recent -Foraminifera (as Polystomella and Calcarina) in which there -were remains of the sarcode-body, that I cannot but believe -the infiltrating mineral to have been dyed by the remains of -sarcode still existing in the canals of Eozoon at the time of its -consolidation. If this be the case, the preservation of this -colour seems to indicate that no considerable metamorphic -action has been exerted upon the rock in which this fossil -occurs. And I should draw the same inference from the fact -that the organic structure of the shell is in many instances -even more completely preserved than it usually is in the -Nummulites and other Foraminifera of the Nummulitic limestone -of the early Tertiaries.</p> - -<p>"To sum up,—That the <i>Eozoon</i> finds its proper place in the -Foraminiferal series, I conceive to be conclusively proved by -its accordance with the great types of that series, in all the -essential characters of organization;—namely, the structure of -the shell forming the proper wall of the chambers, in which it -agrees precisely with Nummulina and its allies; the presence -of an intermediate skeleton and an elaborate canal system, the -disposition of which reminds us most of Calcarina; a mode of -communication of the chambers when they are most completely -separated, which has its exact parallel in Cycloclypeus; -and an ordinary want of completeness of separation between -the chambers, corresponding with that which is characteristic -of Carpenteria.</p> - -<p>"There is no other group of the animal kingdom to which -Eozoon presents the slightest structural resemblance; and to -<span class="pagenum"><a name="Page_89" id="Page_89">« 89 »</a></span> -the suggestion that it may have been of kin to Nullipore, I -can offer the most distinct negative reply, having many years -ago carefully studied the structure of that stony Alga, with -which that of Eozoon has nothing whatever in common.</p> - -<p>"The objections which not unnaturally occur to those familiar -with only the ordinary forms of Foraminifera, as to the admission -of Eozoon into the series, do not appear to me of any -force. These have reference in the first place to the great <i>size</i> -of the organism; and in the second, to its exceptional mode of -growth.</p> - -<p>"1. It must be borne in mind that all the Foraminifera normally -increase by the continuous gemmation of new segments -from those previously formed; and that we have, in the -existing types, the greatest diversities in the extent to which -this gemmation may proceed. Thus in the Globigerinæ, -whose shells cover to an unknown thickness the sea bottom of -all that portion of the Atlantic Ocean which is traversed by -the Gulf Stream, only eight or ten segments are ordinarily -produced by continuous gemmation; and if new segments are -developed from the last of these, they detach themselves so as -to lay the foundation of independent Globigerinæ. On the -other hand in Cycloclypeus, which is a discoidal structure -attaining two and a quarter inches in diameter, the number of -segments formed by continuous gemmation must be many -thousand. Again, the Receptaculites of the Canadian Silurian -rocks, shown by Mr. Salter’s drawings<a name="FNanchor_22" id="FNanchor_22"></a><a href="#Footnote_22" class="fnanchor">[V]</a> to be a gigantic -Orbitolite, attains a diameter of twelve inches; and if this -were to increase by vertical as well as by horizontal gemmation -(after the manner of Tinoporus or Orbitoides) so that one -discoidal layer would be piled on another, it would form a -mass equalling Eozoon in its ordinary dimensions. To say, -therefore, that Eozoon cannot belong to the Foraminifera on -account of its gigantic size, is much as if a botanist who had -only studied plants and shrubs were to refuse to admit a tree -into the same category. The very same continuous gemmation -which has produced an Eozoon would produce an equal -mass of independent Globigerinæ, if after eight or ten repetitions -of the process, the new segments were to detach themselves.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_22" id="Footnote_22"></a><a href="#FNanchor_22"><span class="label">[V]</span></a> <i>First Decade of Canadian Fossils</i>, pl. x.</p> -</div> - -<p><span class="pagenum"><a name="Page_90" id="Page_90">« 90 »</a></span></p> - -<div class="blockquot"> - -<p>"It is to be remembered, moreover, that the largest masses of -sponges are formed by continuous gemmation from an original -Rhizopod segment; and that there is no <i>á priori</i> reason why -a Foraminiferal organism should not attain the same dimensions -as a Poriferal one,—the intimate relationship of the two -groups, notwithstanding the difference between their skeletons, -being unquestionable.</p> - -<p>"2. The difficulty arising from the zoophytic plan of growth -of Eozoon is at once disposed of by the fact that we have in -the recent Polytrema (as I have shown, <i>op. cit.</i>, <a href="#Page_235">p. 235</a>) an -organism nearly allied in all essential points of structure -to Rotalia, yet no less aberrant in its plan of growth, having -been ranked by Lamarck among the Millepores. And it -appears to me that Eozoon takes its place quite as naturally in -the Nummuline series as Polytrema in the Rotaline. As we -are led from the typical Rotalia, through the less regular -Planorbulina, to Tinoporus, in which the chambers are piled -up vertically, as well as multiplied horizontally, and thence -pass by an easy gradation to Polytrema, in which all regularity -of external form is lost; so may we pass from the typical -Operculina or Nummulina, through Heterostegina and Cycloclypeus -to Orbitoides, in which, as in Tinoporus, the chambers -multiply both by horizontal and by vertical gemmation; and -from Orbitoides to Eozoon the transition is scarcely more -abrupt than from Tinoporus to Polytrema.</p> - -<p>"The general acceptance, by the most competent judges, of -my views respecting the primary value of the characters furnished -by the intimate structure of the shell, and the very -subordinate value of plan of growth, in the determination of -the affinities of Foraminifera, renders it unnecessary that I -should dwell further on my reasons for unhesitatingly affirming -the Nummuline affinities of Eozoon from the microscopic -appearances presented by the proper wall of its chambers, -notwithstanding its very aberrant peculiarities; and I cannot -but feel it to be a feature of peculiar interest in geological -inquiry, that the true relations of by far the earliest fossil yet -<span class="pagenum"><a name="Page_91" id="Page_91">« 91 »</a></span> -known should be determinable by the comparison of a portion -which the smallest pin’s head would cover, with organisms at -present existing."</p> -</div> - - -<p class="center">(C.) <span class="smcap">Note on Specimens From Long Lake and Wentworth.</span></p> - -<p class="center smaller">[<i>Journal of Geological Society</i>, August, 1867.]</p> - -<div class="blockquot"> - -<p>"Specimens from Long Lake, in the collection of the Geological -Survey of Canada, exhibit white crystalline limestone -with light green compact or septariiform<a name="FNanchor_23" id="FNanchor_23"></a><a href="#Footnote_23" class="fnanchor">[W]</a> serpentine, and -much resemble some of the serpentine limestones of Grenville. -Under the microscope the calcareous matter presents a delicate -areolated appearance, without lamination; but it is not an -example of acervuline Eozoon, but rather of fragments of such -a structure, confusedly aggregated together, and having the -interstices and cell-cavities filled with serpentine. I have not -found in any of these fragments a canal system similar to that -of Eozoon Canadense, though there are casts of large stolons, -and, under a high power, the calcareous matter shows in many -places the peculiar granular or cellular appearance which is -one of the characters of the supplemental skeleton of that -species. In a few places a tubulated cell-wall is preserved, -with structure similar to that of Eozoon Canadense.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_23" id="Footnote_23"></a><a href="#FNanchor_23"><span class="label">[W]</span></a> I use the term “septariiform” to denote the <i>curdled</i> appearance -so often presented by the Laurentian serpentine.</p> -</div> - -<p><span class="pagenum"><a name="Page_92" id="Page_92">« 92 »</a></span></p> - -<div class="blockquot"> - -<p>“Specimens of Laurentian limestone from Wentworth, in the -collection of the Geological Survey, exhibit many rounded silicious -bodies, some of which are apparently grains of sand, or small -pebbles; but others, especially when freed from the calcareous -matter by a dilute acid, appear as rounded bodies, with rough -surfaces, either separate or aggregated in lines or groups, and -having minute vermicular processes projecting from their surfaces. -At first sight these suggest the idea of spicules; but I -think it on the whole more likely that they are casts of cavities -and tubes belonging to some calcareous Foraminiferal organism -which has disappeared. Similar bodies, found in the -limestone of Bavaria, have been described by Gümbel, who -interprets them in the same way. They may also be compared -with the silicious bodies mentioned in a former paper as -occurring in the loganite filling the chambers of specimens of -<i>Eozoon</i> from Burgess.”</p> - -<p>These specimens will be more fully referred to under -<a href="#CHAPTER_VI">Chapter VI</a>.</p> -</div> - - -<p class="center">(D.) <span class="smcap">Additional Structural Facts.</span></p> - -<div class="blockquot"> - -<p>I may mention here a peculiar and interesting structure -which has been detected in one of my specimens while these -sheets were passing through the press. It is an abnormal -thickening of the calcareous wall, extending across several -layers, and perforated with large parallel cylindrical canals, -filled with dolomite, and running in the direction of the -laminæ; the intervening calcite being traversed by a very fine -and delicate canal system. It makes a nearer approach to -some of the Stromatoporæ mentioned in <a href="#CHAPTER_VI">Chapter VI.</a> than any -other Laurentian structure hitherto observed, and may be -either an abnormal growth of Eozoon, consequent on some -injury, or a parasitic mass of some Stromatoporoid organism -overgrown by the laminæ of the fossil. The structure of the -dolomite in this specimen indicates that it first lined the -canals, and afterward filled them; an appearance which I have -also observed recently in the larger canals filled with serpentine -(<a href="#Plate_VIII">Plate VIII., fig. 5</a>). The cut below is an attempt, only -partially successful, to show the Amœba-like appearance, -when magnified, of the casts of the chambers of Eozoon, as -seen on the decalcified surface of a specimen broken parallel -to the laminæ.</p> -</div> - -<div class="fig_center" style="width: 207px;"> -<a name="fig_21a" id="fig_21a"></a> -<img src="images/fig_21a.png" width="207" height="146" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 21</span><i>a</i>.</p> -</div> - -<div class="bbox2 fig_center" style="width: 650px;"> -<a name="Plate_V" id="Plate_V"></a> -<p class="tdr">Plate V.</p> -<div class="fig_center" style="width: 500px;"> - -<img src="images/plate_5.png" width="342" height="348" alt="" /> - -<p class="center"><i>Nature-print of Eozoon, showing laminated, acervuline, and fragmental -portions.</i></p> - -<p class="cap_center2">This is printed from an electrotype taken from an etched slab of Eozoon, and -not touched with a graver except to remedy some accidental flaws in the plate. -The diagonal white line marks the course of a calcite vein.</p> -</div> -</div> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_93" id="Page_93">« 93 »</a></span></p> - - -<p class="caption2"><a name="CHAPTER_V" id="CHAPTER_V">CHAPTER V.</a><br /> - -THE PRESERVATION OF EOZOON.</p> - - -<p class="p0"><span class="smcap">Perhaps</span> nothing excites more scepticism as to this -ancient fossil than the prejudice existing among -geologists that no organism can be preserved in rocks -so highly metamorphic as those of the Laurentian -series. I call this a prejudice, because any one who -makes the microscopic structure of rocks and fossils -a special study, soon learns that fossils undergo the -most remarkable and complete chemical changes -without losing their minute structure, and that calcareous -rocks if once fossiliferous are hardly ever -so much altered as to lose all trace of the organisms -which they contained, while it is a most common occurrence -to find highly crystalline rocks of this kind -abounding in fossils preserved as to their minute -structure.</p> - -<p>Let us, however, look at the precise conditions -under which this takes place.</p> - -<p>When calcareous fossils of irregular surface and -porous or cellular texture, such as Eozoon was or -corals were and are, become imbedded in clay, marl, -or other soft sediment, they can be washed out and -recovered in a condition similar to that of recent -<span class="pagenum"><a name="Page_94" id="Page_94">« 94 »</a></span> -specimens, except that their pores or cells if open -may be filled with the material of the matrix, or if -not so open that they can be thus filled, they may be -more or less incrusted with mineral deposits introduced -by water, or may even be completely filled up -in this way. But if such fossils are contained in -hard rocks, they usually fail, when these are broken, -to show their external surfaces, and, breaking across -with the containing rock, they exhibit their internal -structure merely,—and this more or less distinctly, -according to the manner in which their cells or cavities -have been filled. Here the microscope becomes -of essential service, especially when the structures -are minute. A fragment of fossil wood which to the -naked eye is nothing but a dark stone, or a coral -which is merely a piece of gray or coloured marble, -or a specimen of common crystalline limestone made -up originally of coral fragments, presents, when sliced -and magnified, the most perfect and beautiful structure. -In such cases it will be found that ordinarily the -original substance of the fossil remains, in a more -or less altered state. Wood may be represented by -dark lines of coaly matter, or coral by its white or -transparent calcareous laminæ; while the material -which has been introduced and which fills the cavities -may so differ in colour, transparency, or crystalline -structure, as to act differently on light, and so reveal -the structure. These fillings are very curious. Sometimes -they are mere earthy or muddy matter. Sometimes -they are pure and transparent and crystalline. -<span class="pagenum"><a name="Page_95" id="Page_95">« 95 »</a></span> -Often they are stained with oxide of iron or coaly -matter. They may consist of carbonate of lime, silica -or silicates, sulphate of baryta, oxides of iron, carbonate -of iron, iron pyrite, or sulphides of copper or -lead, all of which are common materials. They are -sometimes so complicated that I have seen even the -minute cells of woody structures, each with several -bands of differently coloured materials deposited in -succession, like the coats of an onyx agate.</p> - -<p>A further stage of mineralization occurs when the -substance of the organism is altogether removed and -replaced by foreign matter, either little by little, or -by being entirely dissolved or decomposed, leaving -a cavity to be filled by infiltration. In this state -are some silicified woods, and those corals which have -been not filled with but converted into silica, and can -thus sometimes be obtained entire and perfect by the -solution in an acid of the containing limestone, or by -its removal in weathering. In this state are the beautiful -silicified corals obtained from the corniferous limestone -of Lake Erie. It may be well to present to -the eye these different stages of fossilization. I have -attempted to do this in <a href="#fig_22">fig. 22</a>, taking a tabulate -coral of the genus Favosites for an example, and -supposing the materials employed to be calcite and -silica. Precisely the same illustration would apply -to a piece of wood, except that the cell-wall would -be carbonaceous matter instead of carbonate of lime. -In this figure the dotted parts represent carbonate of -lime, the diagonally shaded parts silica or a silicate. -<span class="pagenum"><a name="Page_96" id="Page_96">« 96 »</a></span> -Thus we have, in the natural state, the walls of carbonate -of lime and the cavities empty. When fossilized -the cavities may be merely filled with carbonate -of lime, or they may be filled with silica; or the walls -themselves may be replaced by silica and the cavities -may remain filled with carbonate of lime; or both -the walls and cavities may be represented by or filled -with silica or silicates. The ordinary specimens of -Eozoon are in the third of these stages, though some -exist in the second, and I have reason to believe that -some have reached to the fifth. I have not met with -any in the fourth stage, though this is not uncommon -in Silurian and Devonian fossils.</p> - -<div class="fig_center" style="width: 353px;"> -<a name="fig_22" id="fig_22"></a> -<img src="images/fig_22.png" width="353" height="117" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 22.</span> <i>Diagram showing different States of Fossilization of a Cell -of a Tabulate Coral.</i></p> - -<p class="cap_center">(<i>a.</i>) Natural condition—walls calcite, cell empty. (<i>b.</i>) Walls calcite, cell filled -with the same. (<i>c.</i>) Walls calcite, cell filled with silica or silicate. (<i>d.</i>) Walls -silicified, cell filled with calcite. (<i>e.</i>) Walls silicified, cell filled with silica -or silicate.</p> -</div> - -<p>With regard to the calcareous organisms with which -we have now to do, when these are imbedded in pure -limestone and filled with the same, so that the whole -rock, fossils and all, is identical in composition, and -when metamorphic action has caused the whole to -become crystalline, and perhaps removed the remains -of carbonaceous matter, it may be very difficult to -<span class="pagenum"><a name="Page_97" id="Page_97">« 97 »</a></span> -detect any traces of fossils. But even in this case -careful management of light may reveal indications -of structure, as in some specimens of Eozoon described -by the writer and Dr. Carpenter. In many cases, -however, even where the limestones have become -perfectly crystalline, and the cleavage planes cut freely -across the fossils, these exhibit their forms and minute -structure in great perfection. This is the case in -many of the Lower Silurian limestones of Canada, as -I have elsewhere shown.<a name="FNanchor_24" id="FNanchor_24"></a><a href="#Footnote_24" class="fnanchor">[X]</a> The gray crystalline -Trenton limestone of Montreal, used as a building -stone, is an excellent illustration of this. To the -naked eye it is a gray marble composed of cleavable -crystals; but when examined in thin slices, it shows -its organic fragments in the greatest perfection, and -all the minute structures are perfectly marked out -by delicate carbonaceous lines. The only exception -in this limestone is in the case of the Crinoids, in -which the cellular structure is filled with transparent -calc-spar, perfectly identical with the original solid -matter, so that they appear solid and homogeneous, -and can be recognised only by their external forms. -The specimen represented in <a href="#fig_23">fig. 23</a>, is a mass of -Corals, Bryozoa, and Crinoids, and shows these under -a low power, as represented in the figure; but to the -naked eye it is merely a gray crystalline limestone. -The specimen represented in <a href="#fig_24">fig. 24</a> shows the -Laurentian Eozoon in a similar state of preservation. -<span class="pagenum"><a name="Page_98" id="Page_98">« 98 »</a></span> -It is from a sketch by Dr. Carpenter, and shows the -delicate canals partly filled with calcite as clear and -colourless as that of the shell itself, and distinguishable -only by careful management of the light.</p> - -<div class="footnote"> - -<p><a name="Footnote_24" id="Footnote_24"></a><a href="#FNanchor_24"><span class="label">[X]</span></a> <i>Canadian Naturalist</i>, 1859; Microscopic Structure of Canadian -Limestones.</p> -</div> - -<div class="fig_center" style="width: 328px;"> -<a name="fig_23" id="fig_23"></a> -<img src="images/fig_23.png" width="328" height="177" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 23.</span> <i>Slice of Crystalline Lower Silurian Limestone; showing -Crinoids, Bryozoa, and Corals in fragments.</i></p> -</div> - -<div class="fig_center" style="width: 258px;"> -<a name="fig_24" id="fig_24"></a> -<img src="images/fig_24.png" width="258" height="208" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 24.</span> <i>Wall of Eozoon penetrated with Canals. The unshaded -portions filled with Calcite.</i> (<i>After Carpenter.</i>)</p> -</div> - -<p>In the case of recent and fossil Foraminifers, these—when -not so little mineralized that their chambers -<span class="pagenum"><a name="Page_99" id="Page_99">« 99 »</a></span> -are empty, or only partially filled, which is sometimes -the case even with Eocene Nummulites and Cretaceous -forms of smaller size,—are very frequently filled solid -with calcareous matter, and as Dr. Carpenter well -remarks, even well preserved Tertiary Nummulites -in this state often fail greatly in showing their structures, -though in the same condition they occasionally -show these in great perfection. Among the finest -I have seen are specimens from the Mount of Olives -(<a href="#fig_19">fig. 19</a>), and Dr. Carpenter mentions as equally good -those of the London clay of Bracklesham. But in -no condition do modern Foraminifera or those of the -Tertiary and Mesozoic rocks appear in greater perfection -than when filled with the hydrous silicate of iron -and potash called glauconite, and which gives by -the abundance of its little bottle-green concretions -the name of “green-sand” to formations of this age -both in Europe and America. In some beds of green-sand -every grain seems to have been moulded into -the interior of a microscopic shell, and has retained -its form after the frail envelope has been removed. -In some cases the glauconite has not only filled the -chambers but has penetrated the fine tubulation, and -when the shell is removed, either naturally or by the -action of an acid, these project in minute needles or -bundles of threads from the surface of the cast. It -is in the warmer seas, and especially in the bed of -the Ægean and of the Gulf Stream, that such specimens -are now most usually found. If we ask why this -mineral glauconite should be associated with Foraminiferal -<span class="pagenum"><a name="Page_100" id="Page_100">« 100 »</a></span> -shells, the answer is that they are both products -of one kind of locality. The same sea bottoms in -which Foraminifera most abound are also those in -which for some unknown chemical reason glauconite -is deposited. Hence no doubt the association of this -mineral with the great Foraminiferal formation of the -chalk. It is indeed by no means unlikely that the -selection by these creatures of the pure carbonate of -lime from the sea-water or its minute plants, may be -the means of setting free the silica, iron, and potash, -in a state suitable for their combination. Similar -silicates are found associated with marine limestones, -as far back as the Silurian age; and Dr. Sterry Hunt, -than whom no one can be a better authority on chemical -geology, has argued on chemical grounds that -the occurrence of serpentine with the remains of -Eozoon is an association of the same character.</p> - -<p>However this may be, the infiltration of the pores -of Eozoon with serpentine and other silicates has -evidently been one main means of the preservation of -its structure. When so infiltrated no metamorphism -short of the complete fusion of the containing rock -could obliterate the minutest points of structure; and -that such fusion has not occurred, the preservation in -the Laurentian rocks of the most delicate lamination -of the beds shows conclusively; while, as already -stated, it can be shown that the alteration which has -occurred might have taken place at a temperature far -short of that necessary to fuse limestone. Thus -has it happened that these most ancient fossils have -<span class="pagenum"><a name="Page_101" id="Page_101">« 101 »</a></span> -been handed down to our time in a state of preservation -comparable, as Dr. Carpenter states, to that of -the best preserved fossil Foraminifera from the more -recent formations that have come under his observation -in the course of all his long experience.</p> - -<p>Let us now look more minutely at the nature of -the typical specimens of Eozoon as originally observed -and described, and then turn to those preserved in -other ways, or more or less destroyed and defaced. -Taking a polished specimen from Petite Nation, like -that delineated in <a href="#Plate_V">Plate. V.</a>, we find the shell represented -by white limestone, and the chambers by light -green serpentine. By acting on the surface with a -dilute acid we etch out the calcareous part, leaving -a cast in serpentine of the cavities occupied by the soft -parts; and when this is done in polished slices these -may be made to print their own characters on paper, -as has actually been done in the case of <a href="#Plate_V">Plate. V.</a>, which -is an electrotype taken from an actual specimen, and -shows both the laminated and acervuline parts of -the fossil. If the process of decalcification has been -carefully executed, we find in the excavated spaces -delicate ramifying processes of opaque serpentine or -transparent dolomite, which were originally imbedded -in the calcareous substance, and which are often of -extreme fineness and complexity. (<a href="#Plate_VI">Plate VI.</a> and <a href="#fig_10">fig. 10</a>.) -These are casts of the canals which traversed -the shell when still inhabited by the animal. In some -well preserved specimens we find the original cell-wall -represented by a delicate white film, which under -<span class="pagenum"><a name="Page_102" id="Page_102">« 102 »</a></span> -the microscope shows minute needle-like parallel processes -representing its still finer tubuli. It is evident -that to have filled these tubuli the serpentine must -have been introduced in a state of actual solution, -and must have carried with it no foreign impurities. -Consequently we find that in the chambers themselves -the serpentine is pure; and if we examine it under -polarized light, we see that it presents a singularly -curdled or irregularly laminated appearance, which I -have designated under the name septariiform, as if -it had an imperfectly crystalline structure, and had -been deposited in irregular laminæ, beginning at the -sides of the chambers, and filling them toward the -middle, and had afterward been cracked by shrinkage, -and the cracks filled with a second deposit of serpentine. -Now, serpentine is a hydrous silicate of magnesia, -and all that we need to suppose is that in the -deposits of the Laurentian sea magnesia was present -instead of iron and potash, and we can understand -that the Laurentian fossil has been petrified by infiltration -with serpentine, as more modern Foraminifera -have been with glauconite, which, though it usually -has little magnesia, often has a considerable percentage -of alumina. Further, in specimens of Eozoon -from Burgess, the filling mineral is loganite, a compound -of silica, alumina, magnesia and iron, with -water, and in certain Silurian limestones from New -Brunswick and Wales, in which the delicate microscopic -pores of the skeletons of stalked star-fishes or -Crinoids have been filled with mineral deposits, so -<span class="pagenum"><a name="Page_103" id="Page_103">« 103 »</a></span> -that when decalcified these are most beautifully represented -by their casts, Dr. Hunt has proved the filling -mineral to be a silicate of alumina, iron, magnesia -and potash, intermediate between serpentine and -glauconite. We have, therefore, ample warrant for -adhering to Dr. Hunt’s conclusion that the Laurentian -serpentine was deposited under conditions similar -to those of the modern green-sand. Indeed, independently -of Eozoon, it is impossible that any geologist -who has studied the manner in which this mineral -is associated with the Laurentian limestones could -believe it to have been formed in any other way. Nor -<span class="pagenum"><a name="Page_104" id="Page_104">« 104 »</a></span> -need we be astonished at the fineness of the infiltration -by which these minute tubes, perhaps <span class="horsplit"><span class="top">1</span><span class="bottom trt">10000</span></span> of -an inch in diameter, are filled with mineral matter. -The micro-geologist well knows how, in more modern -deposits, the finest pores of fossils are filled, and that -mineral matter in solution can penetrate the smallest -openings that the microscope can detect. Wherever the -fluids of the living body can penetrate, there also mineral -substances can be carried, and this natural injection, -effected under great pressure and with the advantage -of ample time, can surpass any of the feats of the -anatomical manipulator. <a href="#fig_25">Fig. 25</a> represents a microscopic -joint of a Crinoid from the Upper Silurian of -New Brunswick, injected with the hydrous silicate -already referred to, and <a href="#fig_26">fig. 26</a> shows a microscopic -<span class="pagenum"><a name="Page_105" id="Page_105">« 105 »</a></span> -chambered or spiral shell, from a Welsh Silurian -limestone, with its cavities filled with a similar substance.</p> - -<div class="fig_left" style="width: 178px;"> -<a name="fig_25" id="fig_25"></a> -<img src="images/fig_25.png" width="178" height="336" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 25.</span> <i>Joint of a Crinoid, having its pores injected with a -Hydrous Silicate.</i></p> - -<p class="cap_center2">Upper Silurian Limestone, Pole Hill, New Brunswick. Magnified 25 diameters.</p> -</div> - -<div class="fig_right" style="width: 163px;"> -<a name="fig_26" id="fig_26"></a> -<img src="images/fig_26.png" width="163" height="244" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 26.</span> <i>Shell from a Silurian Limestone, Wales; its cavity filled -with a Hydrous Silicate.</i></p> - -<p class="cap_center2">Magnified 25 diameters.</p> -</div> - -<p>It is only necessary to refer to the attempts which -have been made to explain by merely mineral deposits -the occurrence of the serpentine in the canals and -chambers of Eozoon, and its presenting the form it -does, to see that this is the case. Prof. Rowney, for -example, to avoid the force of the argument from the -canal system, is constrained to imagine that the whole -mass has at one time been serpentine, and that this has -been partially washed away, and replaced by calcite. If -so, whence the deposition of the supposed mass of serpentine, -which has to be accounted for in this way as -well as in the other? How did it happen to be eroded -into so regular chambers, leaving intermediate floors -and partitions. And, more wonderful still, how did -the regular dendritic bundles, so delicate that they are -removed by a breath, remain perfect, and endure until -they were imbedded in calcareous spar? Further, how -does it happen that in some specimens serpentine and -pyroxene seem to have encroached upon the structure, -as if they and not calcite were the eroding minerals? -How any one who has looked at the structures can for -a moment imagine such a possibility, it is difficult to -understand. If we could suppose the serpentine to have -been originally deposited as a cellular or laminated mass, -and its cavities filled with calcite in a gelatinous or semi-fluid -state, we might suppose the fine processes of serpentine -to have grown outward into these cavities in -<span class="pagenum"><a name="Page_106" id="Page_106">« 106 »</a></span> -the mass, as fibres of oxide of iron or manganese have -grown in the silica of moss-agate; but this theory -would be encompassed with nearly as great mechanical -and chemical difficulties. The only rational view that -any one can take of the process is, that the calcareous -matter was the original substance, and that it had -delicate tubes traversing it which became injected with -serpentine. The same explanation, and no other, will -suffice for those delicate cell-walls, penetrated by innumerable -threads of serpentine, which must have been -injected into pores. It is true that there are in some -of the specimens cracks filled with fibrous serpentine or -chrysotile, but these traverse the mass in irregular -directions, and they consist of closely packed angular -prisms, instead of a matrix of limestone penetrated by -cylindrical threads of serpentine. (<a href="#fig_27">Fig. 27.</a>) Here I -must once for all protest against the tendency of some -opponents of Eozoon to confound these structures and -the canal system of Eozoon with the acicular crystals, -and dendritic or coralloidal forms, observed in some -minerals. It is easy to make such comparisons appear -plausible to the uninitiated, but practised observers -cannot be so deceived, the differences are too marked -<span class="pagenum"><a name="Page_107" id="Page_107">« 107 »</a></span> -and essential. In illustration of this, I may refer to the -highly magnified canals in figs. 28 and 29. Further, -it is evident from the examination of the specimens, -that the chrysotile veins, penetrating as they often do -diagonally or transversely across both chambers and -walls, must have originated subsequently to the origin -and hardening of the rock and its fossils, and result -from aqueous deposition of fibrous serpentine in cracks -which traverse alike the fossils and their matrix. In -<span class="pagenum"><a name="Page_108" id="Page_108">« 108 »</a></span> -specimens now before me, nothing can be more plain -than this entire independence of the shining silky -veins of fibrous serpentine, and the fact of their -having been formed subsequently to the fossilization of -the Eozoon; since they can be seen to run across the -lamination, and to branch off irregularly in lines altogether -distinct from the structure. This, while it -shows that these veins have no connection with the -fossil, shows also that the latter was an original -ingredient of the beds when deposited, and not a -product of subsequent concretionary action.</p> - -<div class="fig_center" style="width: 232px;"> -<a name="fig_27" id="fig_27"></a> -<img src="images/fig_27.png" width="232" height="86" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 27.</span> <i>Diagram showing the different appearances of the cell-wall -of Eozoon and of a vein of Chrysotile, when highly magnified.</i></p> -</div> - -<div class="fig_center" style="width: 364px;"> -<a name="fig_28-29" id="fig_28-29"></a> -<img src="images/fig_28.png" width="364" height="175" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 28.</span> <i>Casts of Canals of Eozoon in Serpentine, decalcified and -highly magnified.</i></p> -</div> - -<div class="fig_right" style="width: 166px;"> -<a name="fig_29" id="fig_29"></a> -<img src="images/fig_29.png" width="166" height="155" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 29.</span> <i>Canals of Eozoon.</i></p> - -<p class="cap_center2">Highly magnified.</p> -</div> - -<p>Taking the specimens preserved by serpentine as -typical, we now turn to certain other and, in some -respects, less characteristic specimens, which are nevertheless -very instructive. At the Calumet some of the -masses are partly filled with serpentine and partly with -white pyroxene, an anhydrous silicate of lime and -magnesia. The two minerals can readily be distinguished -when viewed with polarized light; and in -some slices I have seen part of a chamber or group of -canals filled with serpentine and part with pyroxene. -In this case the pyroxene or the materials which now -compose it, must have been introduced by infiltration, -as well as the serpentine. This is the more remarkable -as pyroxene is most usually found as an ingredient of -igneous rocks; but Dr. Hunt has shown that in the -Laurentian limestones and also in veins traversing -them, it occurs under conditions which imply its deposition -from water, either cold or warm. Gümbel -remarks on this:—"Hunt, in a very ingenious -<span class="pagenum"><a name="Page_109" id="Page_109">« 109 »</a></span> -manner, compares this formation and deposition of -serpentine, pyroxene, and loganite, with that of glauconite, -whose formation has gone on uninterruptedly -from the Silurian to the Tertiary period, and is even -now taking place in the depths of the sea; it being -well known that Ehrenberg and others have already -shown that many of the grains of glauconite are casts -of the interior of foraminiferal shells. In the light of -this comparison, the notion that the serpentine and -such like minerals of the primitive limestones have -been formed, in a similar manner, in the chambers of -Eozoic Foraminifera, loses any traces of improbability -which it might at first seem to possess."</p> - -<p>In many parts of the skeleton of Eozoon, and even -in the best infiltrated serpentine specimens, there are -portions of the cell-wall and canal system which have -been filled with calcareous spar or with dolomite, so -similar to the skeleton that it can be detected only -under the most favourable lights and with great care. -(Fig. 24, <i>supra</i>.) The same phenomena may be observed -in joints of Crinoids from the Palæozoic rocks, -and they constitute proofs of organic origin even more -irrefragable than the filling with serpentine. Dr. -Carpenter has recently, in replying to the objections of -Mr. Carter, made excellent use of this feature of the -preservation of Eozoon. It is further to be remarked -that in all the specimens of true Eozoon, as well as in -many other calcareous fossils preserved in ancient -rocks, the calcareous matter, even when its minute -structures are not preserved or are obscured, presents -<span class="pagenum"><a name="Page_110" id="Page_110">« 110 »</a></span> -a minutely granular or curdled appearance, arising no -doubt from the original presence of organic matter, -and not recognised in purely inorganic calcite.</p> - -<p>Another style of these remarkable fossils is that of -the Burgess specimens. In these the walls have been -changed into dolomite or magnesian limestone, and -the canals seem to have been wholly obliterated, so -that only the laminated structure remains. The -material filling the chambers is also an aluminous -silicate named loganite; and this seems to have been -introduced, not so much in solution, as in the state of -muddy slime, since it contains foreign bodies, as grains -of sand and little groups of silicious concretions, some -of which are not unlikely casts of the interior of -minute foraminiferal shells contemporary with Eozoon, -and will be noticed in the sequel.</p> - -<div class="fig_center" style="width: 371px;"> -<a name="fig_30" id="fig_30"></a> -<img src="images/fig_30.png" width="371" height="395" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 30.</span> <i>Eozoon from Tudor.</i></p> - -<p class="cap_center2">Two-thirds natural size. (<i>a.</i>) Tubuli. (<i>b.</i>) Canals. Magnified. -<i>a</i> and <i>b</i> from another specimen.</p> -</div> - -<p>Still another mode of occurrence is presented by a -remarkable specimen from Tudor in Ontario, and from -beds probably on the horizon of the Upper Laurentian -or Huronian.<a name="FNanchor_25" id="FNanchor_25"></a><a href="#Footnote_25" class="fnanchor">[Y]</a> It occurs in a rock scarcely at all -metamorphic, and the fossil is represented by white -carbonate of lime, while the containing matrix is a -dark-coloured coarse limestone. In this specimen the -material filling the chambers has not penetrated the -canals except in a few places, where they appear filled -with dark carbonaceous matter. In mode of preservation -these Tudor specimens much resemble the -ordinary fossils of the Silurian rocks. One of the -specimens in the collection of the Geological Survey -<span class="pagenum"><a name="Page_111" id="Page_111">« 111 »</a></span> -(<a href="#fig_30">fig. 30</a>) presents a clavate form, as if it had been a -detached individual supported on one end at the bottom -of the sea. It shows, as does also the original Calumet -specimen, the septa approaching each other and coalescing -at the margin of the form, where there were -probably orifices communicating with the exterior. -Other specimens of fragmental Eozoon from the Petite -Nation localities have their canals filled with dolomite, -which probably penetrated them after they were -<span class="pagenum"><a name="Page_112" id="Page_112">« 112 »</a></span> -broken up and imbedded in the rock. I have ascertained -with respect to these fragments of Eozoon, that -they occur abundantly in certain layers of the Laurentian -limestone, beds of some thickness being in great -part made up of them, and coarse and fine fragments -occur in alternate layers, like the broken corals in -some Silurian limestones.</p> - -<div class="footnote"> - -<p><a name="Footnote_25" id="Footnote_25"></a><a href="#FNanchor_25"><span class="label">[Y]</span></a> See <a href="#NoteB">Note B</a>, Chap. III.</p> -</div> - -<p>Finally, on this part of the subject, careful observation -of many specimens of Laurentian limestone which -present no trace of Eozoon when viewed by the naked -eye, and no evidence of structure when acted on with -acids, are nevertheless organic, and consist of fragments -of Eozoon, and possibly of other organisms, not infiltrated -with silicates, but only with carbonate of lime, -and consequently revealing only obscure indications of -their minute structure. I have satisfied myself of -this by long and patient investigations, which scarcely -admit of any adequate representation, either by words -or figures.</p> - -<p>Every worker in those applications of the microscope -to geological specimens which have been termed micro-geology, -is familiar with the fact that crystalline forces -and mechanical movements of material often play the -most fantastic tricks with fossilized organic matter. In -fossil woods, for example, we often have the tissues -disorganized, with radiating crystallizations of calcite -and little spherical concretions of quartz, or disseminated -cubes and grains of pyrite, or little veins filled -with sulphate of barium or other minerals. We need -not, therefore, be surprised to find that in the venerable -<span class="pagenum"><a name="Page_113" id="Page_113">« 113 »</a></span> -rocks containing Eozoon, such things occur in the -more highly crystalline parts of the limestones, and -even in some still showing traces of the fossil. We -find many disseminated crystals of magnetite, pyrite, -spinel, mica, and other minerals, curiously curved -prisms of vermicular mica, bundles of aciculi of tremolite -and similar substances, veins of calcite and crysolite -or fibrous serpentine, which often traverse the -best specimens. Where these occur abundantly we -usually find no organic structures remaining, or if -they exist they are in a very defective state of preservation. -Even in specimens presenting the lamination -of Eozoon to the naked eye, these crystalline actions -have often destroyed the minute structure; and I fear -that some microscopists have been victimised by -having under their consideration only specimens in -which the actual characters had been too much defaced -to be discernible. I must here state that I have -found some of the specimens sold under the name of -Eozoon Canadense by dealers in microscopical objects -to be almost or quite worthless, being destitute of -any good structure, and often merely pieces of Laurentian -limestone with serpentine grains only. I fear -that the circulation of such specimens has done much -to cause scepticism as to the Foraminiferal nature of -Eozoon. No mistake can be greater than to suppose -that any and every specimen of Laurentian limestone -must contain Eozoon. More especially have I hitherto -failed to detect traces of it in those carbonaceous or -graphitic limestones which are so very abundant in -<span class="pagenum"><a name="Page_114" id="Page_114">« 114 »</a></span> -the Laurentian country. Perhaps where vegetable -matter was very abundant Eozoon did not thrive, or -on the other hand the growth of Eozoon may have -diminished the quantity of vegetable matter. It is -also to be observed that much compression and distortion -have occurred in the beds of Laurentian limestone -and their contained fossils, and also that the specimens -are often broken by faults, some of which are so small -as to appear only on microscopic examination, and to -shift the plates of the fossil just as if they were beds of -rock. This, though it sometimes produces puzzling -appearances, is an evidence that the fossils were hard -and brittle when this faulting took place, and is consequently -an additional proof of their extraneous origin. -In some specimens it would seem that the lower and -older part of the fossil had been wholly converted into -serpentine or pyroxene, or had so nearly experienced -this change that only small parts of the calcareous wall -can be recognised. These portions correspond with -fossil woods altogether silicified, not only by the filling -of the cells, but also by the conversion of the walls -into silica. I have specimens which manifestly show -the transition from the ordinary condition of filling -with serpentine to one in which the cell-walls are -represented obscurely by one shade of this mineral -and the cavities by another.</p> - -<p>The above considerations as to mode of preservation -of Eozoon concur with those in previous chapters in -showing its oceanic character; but the ocean of the -Eozoic period may not have been so deep as at -<span class="pagenum"><a name="Page_115" id="Page_115">« 115 »</a></span> -present, and its waters were probably warm and well -stocked with mineral matters derived from the newly -formed land, or from hot springs in its own bottom. -On this point the interesting investigations of Dr. -Hunt with reference to the chemical conditions of the -Silurian seas, allow us to suppose that the Laurentian -ocean may have been much more richly stored, more -especially with salts of lime and magnesia, than that -of subsequent times. Hence the conditions of warmth, -light, and nutriment, required by such gigantic Protozoans -would all be present, and hence, also no doubt, -some of the peculiarities of its mineralization.</p> - - -<hr class="r20" /> - -<p class="caption3">NOTES TO CHAPTER V.</p> - -<p class="center">(A.) <span class="smcap">Dr. Sterry Hunt on the Mineralogy of Eozoon and -the containing Rocks.</span></p> - -<div class="blockquot"> - -<p>It was fortunate for the recognition of Eozoon that Dr. -Hunt had, before its discovery, made so thorough researches -into the chemistry of the Laurentian series, and was prepared -to show the chemical possibilities of the preservation of fossils -in these ancient deposits. The following able summary of his -views was appended to the original description of the fossil in -the <i>Journal of the Geological Society</i>.</p> - -<p>"The details of structure have been preserved by the introduction -of certain mineral silicates, which have not only filled -up the chambers, cells, and canals left vacant by the disappearance -of the animal matter, but have in very many cases -been injected into the tubuli, filling even their smallest ramifications. -These silicates have thus taken the place of the -original sarcode, while the calcareous septa remain. It will -then be understood that when the replacement of the Eozoon -by silicates is spoken of, this is to be understood of the soft -<span class="pagenum"><a name="Page_116" id="Page_116">« 116 »</a></span> -parts only; since the calcareous skeleton is preserved, in most -cases, without any alteration. The vacant spaces left by the -decay of the sarcode may be supposed to have been filled by a -process of infiltration, in which the silicates were deposited -from solution in water, like the silica which fills up the pores -of wood in the process of silicification. The replacing silicates, -so far as yet observed, are a white pyroxene, a pale green -serpentine, and a dark green alumino-magnesian mineral, -which is allied in composition to chlorite and to pyrosclerite, -and which I have referred to loganite. The calcareous septa -in the last case are found to be dolomitic, but in the other instances -are nearly pure carbonate of lime. The relations of -the carbonate and the silicates are well seen in thin sections -under the microscope, especially by polarized light. The -calcite, dolomite, and pyroxene exhibit their crystalline structure -to the unaided eye; and the serpentine and loganite are -also seen to be crystalline when examined with the microscope. -When portions of the fossil are submitted to the action of an -acid, the carbonate of lime is dissolved, and a coherent mass -of serpentine is obtained, which is a perfect cast of the soft -parts of the Eozoon. The form of the sarcode which filled -the chambers and cells is beautifully shown, as well as the -connecting canals and the groups of tubuli; these latter are -seen in great perfection upon surfaces from which the carbonate -of lime has been partially dissolved. Their preservation -is generally most complete when the replacing mineral is serpentine, -although very perfect specimens are sometimes -found in pyroxene. The crystallization of the latter mineral -appears, however, in most cases to have disturbed the calcareous -septa.</p> - -<p>"Serpentine and pyroxene are generally associated in these -specimens, as if their disposition had marked different stages -of a continuous process. At the Calumet, one specimen of the -fossil exhibits the whole of the sarcode replaced by serpentine; -while, in another one from the same locality, a layer of -pale green translucent serpentine occurs in immediate contact -with the white pyroxene. The calcareous septa in this specimen -are very thin, and are transverse to the plane of contact -<span class="pagenum"><a name="Page_117" id="Page_117">« 117 »</a></span> -of the two minerals; yet they are seen to traverse both the -pyroxene and the serpentine without any interruption or -change. Some sections exhibit these two minerals filling adjacent -cells, or even portions of the same cell, a clear line of -division being visible between them. In the specimens from -Grenville on the other hand, it would seem as if the development -of the Eozoon (considerable masses of which were replaced -by pyroxene) had been interrupted, and that a second -growth of the animal, which was replaced by serpentine, had -taken place upon the older masses, filling up their interstices."</p> - -<p>[Details of chemical composition are then given.]</p> - -<p>"When examined under the microscope, the loganite which -replaces the Eozoon of Burgess shows traces of cleavage-lines, -which indicate a crystalline structure. The grains of -insoluble matter found in the analysis, chiefly of quartz-sand, -are distinctly seen as foreign bodies imbedded in the mass, -which is moreover marked by lines apparently due to cracks -formed by a shrinking of the silicate, and subsequently filled -by a further infiltration of the same material. This arrangement -resembles on a minute scale that of septaria. Similar -appearances are also observed in the serpentine which replaces -the Eozoon of Grenville, and also in a massive serpentine -from Burgess, resembling this, and enclosing fragments of -the fossil. In both of these specimens also grains of mechanical -impurities are detected by the microscope; they are -however, rarer than in the loganite of Burgess.</p> - -<p>"From the above facts it may be concluded that the various -silicates which now constitute pyroxene, serpentine, and -loganite were directly deposited in waters in the midst of -which the Eozoon was still growing, or had only recently -perished; and that these silicates penetrated, enclosed, and -preserved the calcareous structure precisely as carbonate of -lime might have done. The association of the silicates with -the Eozoon is only accidental; and large quantities of them, -deposited at the same time, include no organic remains. Thus, -for example, there are found associated with the Eozoon limestones -of Grenville, massive layers and concretions of pure -<span class="pagenum"><a name="Page_118" id="Page_118">« 118 »</a></span> -serpentine; and a serpentine from Burgess has already been -mentioned as containing only small broken fragments of the -fossil. In like manner large masses of white pyroxene, often -surrounded by serpentine, both of which are destitute of traces -of organic structure, are found in the limestone at the Calumet. -In some cases, however, the crystallization of the pyroxene -has given rise to considerable cleavage-planes, and has -thus obliterated the organic structures from masses which, -judging from portions visible here and there, appear to have -been at one time penetrated by the calcareous plates of Eozoon. -Small irregular veins of crystalline calcite, and of serpentine, -are found to traverse such pyroxene masses in the Eozoon -limestone of Grenville.</p> - -<p>"It appears that great beds of the Laurentian limestones -are composed of the ruins of the Eozoon. These rocks, -which are white, crystalline, and mingled with pale green serpentine, -are similar in aspect to many of the so-called primary -limestones of other regions. In most cases the limestones -are non-magnesian, but one of them from Grenville was found -to be dolomitic. The accompanying strata often present finely -crystallized pyroxene, hornblende, phlogopite, apatite, and -other minerals. These observations bring the formation of -silicious minerals face to face with life, and show that their -generation was not incompatible with the contemporaneous -existence and the preservation of organic forms. They confirm, -moreover, the view which I some years since put forward, -that these silicated minerals have been formed, not by subsequent -metamorphism in deeply buried sediments, but by reactions -going on at the earth’s surface.<a name="FNanchor_26" id="FNanchor_26"></a><a href="#Footnote_26" class="fnanchor">[Z]</a> In support of this -view, I have elsewhere referred to the deposition of silicates -of lime, magnesia, and iron from natural waters, to the great -beds of sepiolite in the unaltered Tertiary strata of Europe; -to the contemporaneous formation of neolite (an aluimino-magnesian -silicate related to loganite and chlorite in composition); -and to glauconite, which occurs not only in Secondary, -Tertiary, and Recent deposits, but also, as I have shown, in -<span class="pagenum"><a name="Page_119" id="Page_119">« 119 »</a></span> -Lower Silurian strata.<a name="FNanchor_27" id="FNanchor_27"></a><a href="#Footnote_27" class="fnanchor">[AA]</a> This hydrous silicate of protoxide of -iron and potash, which sometimes includes a considerable -proportion of alumina in its composition, has been observed -by Ehrenberg, Mantell, and Bailey, associated with organic -forms in a manner which seems identical with that in which -pyroxene, serpentine, and loganite occur with the Eozoon in -the Laurentian limestones. According to the first of these -observers, the grains of green-sand, or glauconite, from the -Tertiary limestone of Alabama, are casts of the interior of -Polythalamia, the glauconite having filled them by ‘a species -of natural injection, which is often so perfect that not only the -large and coarse cells, but also the very finest canals of the -cell-walls and all their connecting tubes, are thus petrified and -separately exhibited.’ Bailey confirmed these observations, -and extended them. He found in various Cretaceous and -Tertiary limestones of the United States, casts in glauconite, -not only of <i>Foraminifera</i>, but of spines of <i>Echinus</i>, and of the -cavities of corals. Besides, there were numerous red, green, -and white casts of minute anastomosing tubuli, which, according -to Bailey, resemble the casts of the holes made by burrowing -sponges (<i>Cliona</i>) and worms. These forms are seen -after the dissolving of the carbonate of lime by a dilute acid. -He found, moreover, similar casts of <i>Foraminifera</i>, of minute -mollusks, and of branching tubuli, in mud obtained from -soundings in the Gulf Stream, and concluded that the deposition -of glauconite is still going on in the depths of the sea.<a name="FNanchor_28" id="FNanchor_28"></a><a href="#Footnote_28" class="fnanchor">[AB]</a> -Pourtales has followed up these investigations on the recent -formation of glauconite in the Gulf Stream waters. He has -observed its deposition also in the cavities of <i>Millepores</i>, and -in the canals in the shells of <i>Balanus</i>. According to him, the -glauconite grains formed in <i>Foraminifera</i> lose after a time -their calcareous envelopes, and finally become ‘conglomerated -into small black pebbles,’ sections of which still show under a -microscope the characteristic spiral arrangement of the cells.<a name="FNanchor_29" id="FNanchor_29"></a><a href="#Footnote_29" class="fnanchor">[AC]</a></p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_26" id="Footnote_26"></a><a href="#FNanchor_26"><span class="label">[Z]</span></a> <i>Silliman’s Journal</i> [2], xxix., p. 284; xxxii., p. 286. <i>Geology of -Canada</i>, p. 577.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_27" id="Footnote_27"></a><a href="#FNanchor_27"><span class="label">[AA]</span></a> <i>Silliman’s Journal</i> [2], xxxiii., p. 277. <i>Geology of Canada</i>, -p. 487.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_28" id="Footnote_28"></a><a href="#FNanchor_28"><span class="label">[AB]</span></a> <i>Silliman’s Journal</i> [2], xxii., p. 280.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_29" id="Footnote_29"></a><a href="#FNanchor_29"><span class="label">[AC]</span></a> <i>Report of United States Coast-Survey</i>, 1858, p. 248.</p> - -<p><span class="pagenum"><a name="Page_120" id="Page_120">« 120 »</a></span></p> -</div> - -<div class="blockquot"> - -<p>“It appears probable from these observations that glauconite -is formed by chemical reactions in the ooze at the bottom of -the sea, where dissolved silica comes in contact with iron -oxide rendered soluble by organic matter; the resulting -silicate deposits itself in the cavities of shells and other -vacant spaces. A process analogous to this in its results, has -filled the chambers and canals of the Laurentian <i>Foraminifera</i> -with other silicates; from the comparative rarity of mechanical -impurities in these silicates, however, it would appear that -they were deposited in clear water. Alumina and oxide of -iron enter into the composition of loganite as well as of glauconite; -but in the other replacing minerals, pyroxene and -serpentine, we have only silicates of lime and magnesia, which -were probably formed by the direct action of alkaline silicates, -either dissolved in surface-waters, or in those of submarine -springs, upon the calcareous and magnesian salts of the sea-water.”</p> - -<p>[As stated in the text, the canals of Eozoon are sometimes -filled with dolomite, or in part with serpentine and in part -with dolomite.]</p> -</div> - - -<p class="center">(B.) <span class="smcap">Silurian Limestones holding Fossils infiltrated with -Hydrous Silicate.</span></p> - -<div class="blockquot"> - -<p>Since my attention has been directed to this subject, many -illustrations have come under my notice of Silurian limestones -in which the pores of fossils are infiltrated with hydrous -silicates akin to glauconite and serpentine. A limestone of -this kind, collected by Mr. Robb, at Pole Hill, in New Brunswick, -afforded not only beautiful specimens of portions of Crinoids -preserved in this way, but a sufficient quantity of the material -was collected for an exact analysis, a note on which was published -in the Proceedings of the Royal Irish Academy, 1871.</p> - -<p>The limestone of Pole Hill is composed almost wholly of -organic fragments, cemented by crystalline carbonate of lime, -and traversed by slender veins of the same mineral. Among -the fragments may be recognised under the microscope portions -of Trilobites, and of brachiopod and gastropod shells, -and numerous joints and plates of Crinoids. The latter are -<span class="pagenum"><a name="Page_121" id="Page_121">« 121 »</a></span> -remarkable for the manner in which their reticulated structure, -which is similar to that of modern Crinoids, has been injected -with a silicious substance, which is seen distinctly in slices, -and still more plainly in decalcified specimens. This filling is -precisely similar in appearance to the serpentine filling the -canals of Eozoon, the only apparent difference being in the -forms of the cells and tubes of the Crinoids, as compared with -those of the Laurentian fossil; the same silicious substance -also occupies the cavities of some of the small shells, and -occurs in mere amorphous pieces, apparently filling interstices. -From its mode of occurrence, I have not the slightest doubt -that it occupied the cavities of the crinoidal fragments while -still recent, and before they had been cemented together by -the calcareous paste. This silicious filling is therefore similar -on the one hand to that effected by the ancient serpentine of -the Laurentian, and on the other to that which results from the -depositions of modern glauconite. The analysis of Dr. Hunt, -which I give below, fully confirms these analogies.</p> - -<p>I may add that I have examined under the microscope portions -of the substance prepared by Dr. Hunt for analysis, and -find it to retain its form, showing that it is the actual filling -of the cavities. I have also examined the small amount of -insoluble silica remaining after his treatment with acid and -alkaline solvents, and find it to consist of angular and rounded -grains of quartzose sand.</p> - -<p>The following are Dr. Hunt’s notes:—</p> - -<p>"The fossiliferous limestone from Pole Hill, New Brunswick, -probably of Upper Silurian age, is light gray and coarsely -granular. When treated with dilute hydrochloric acid, it -leaves a residue of 5·9 per cent., and the solution gives 1·8 per -cent. of alumina and oxide of iron, and magnesia equal to 1·35 -of carbonate—the remainder being carbonate of lime. The -insoluble matter separated by dilute acid, after washing by -decantation from a small amount of fine flocculent matter, -consists, apart from an admixture of quartz grains, entirely of -casts and moulded forms of a peculiar silicate, which Dr. -Dawson has observed in decalcified specimens filling the pores -of crinoidal stems; and which when separated by an acid, -<span class="pagenum"><a name="Page_122" id="Page_122">« 122 »</a></span> -resembles closely under the microscope the coralloidal forms -of arragonite known as <i>flos ferri</i>, the surfaces being somewhat -rugose and glistening with crystalline faces. This silicate is -sub-translucent, and of a pale green colour, but immediately -becomes of a light reddish brown when heated to redness in -the air, and gives off water when heated in a tube, without -however, changing its form. It is partially decomposed by -strong hydrochloric acid, yielding a considerable amount of -protosalt of iron. Strong hot sulphuric acid readily and completely -decomposes it, showing it to be a silicate of alumina -and ferrous oxide, with some magnesia and alkalies, but with -no trace of lime. The separated silica, which remains after the -action of the acid, is readily dissolved by a dilute solution of -soda, leaving behind nothing but angular and partially rounded -grains of sand, chiefly of colourless vitreous quartz. An -analysis effected in the way just described on 1·187 grammes -gave the following results, which give, by calculation, the centesimal -composition of the mineral:—</p> -</div> - -<table summary="composition"> -<tr> - <td class="tdl">Silica</td> - <td> </td> - <td class="tdr">·3290</td> - <td> </td> - <td class="tdr">38·93</td> - <td></td> - <td class="tdl">=</td> - <td class="tdr">20·77</td> - <td class="tdl">oxygen.</td> -</tr> -<tr> - <td class="tdl">Alumina</td> - <td></td> - <td class="tdr">·2440</td> - <td></td> - <td class="tdr">28·88</td> - <td></td> - <td class="tdl">=</td> - <td class="tdr">13·46</td> - <td class="center">"</td> -</tr> -<tr> - <td class="tdl">Protoxyd of iron</td> - <td></td> - <td class="tdr">·1593</td> - <td></td> - <td class="tdr">18·86</td> - <td class="center" rowspan="4"><img src="images/bracer_86.png" width="14" height="86" alt="" /></td> - <td class="tdl" rowspan="4">=</td> - <td class="tdr" rowspan="4">6·29</td> - <td class="center">"</td> -</tr> -<tr> - <td class="tdl">Magnesia</td> - <td></td> - <td class="tdr">·0360</td> - <td></td> - <td class="tdr">4·25</td> -</tr> -<tr> - <td class="tdl">Potash</td> - <td></td> - <td class="tdr">·0140</td> - <td></td> - <td class="tdr">1·69</td> -</tr> -<tr> - <td class="tdl">Soda</td> - <td></td> - <td class="tdr">·0042</td> - <td></td> - <td class="tdr">·48</td> -</tr> -<tr> - <td class="tdl">Water</td> - <td></td> - <td class="tdr">·0584</td> - <td></td> - <td class="tdr">6·91</td> - <td></td> - <td class="tdr">=</td> - <td class="tdr">6·14</td> - <td class="center">"</td> -</tr> -<tr> - <td class="tdl">Insoluble, quartz</td> - <td></td> - <td class="tdr bdb">·3420</td> - <td></td> - <td class="bdb"></td> - <td colspan="4"></td> -</tr> -<tr> - <td colspan="2"></td> - <td class="tdr">1·1869</td> - <td></td> - <td class="tdr">100·00</td> - <td colspan="4"></td> -</tr> -</table> - -<div class="blockquot"> - -<p>"A previous analysis of a portion of the mixture by fusion -with carbonate of soda gave, by calculation, 18·80 p. c. of protoxide -of iron, and amounts of alumina and combined silica -closely agreeing with those just given.</p> - -<p>"The oxygen ratios, as above calculated, are nearly as 3 : 2 : -1 : 1. This mineral approaches in composition to the jollyte of -Von Kobell, from which it differs in containing a portion of -alkalies, and only one half as much water. In these respects -it agrees nearly with the silicate found by Robert Hoffman, at -Raspenau, in Bohemia, where it occurs in thin layers alternating -<span class="pagenum"><a name="Page_123" id="Page_123">« 123 »</a></span> -with picrosmine, and surrounding masses of Eozoon in -the Laurentian limestones of that region;<a name="FNanchor_30" id="FNanchor_30"></a><a href="#Footnote_30" class="fnanchor">[AD]</a> the Eozoon itself -being there injected with a hydrous silicate which may be -described as intermediate between glauconite and chlorite in -composition. The mineral first mentioned is compared by -Hoffman to fahlunite, to which jollyte is also related in physical -characters as well as in composition. Under the names of -fahlunite, gigantolite, pinite, etc., are included a great class of -hydrous silicates, which from their imperfectly crystalline -condition, have generally been regarded, like serpentine, as -results of the alteration of other silicates. It is, however, -difficult to admit that the silicate found in the condition -described by Hoffman, and still more the present mineral, -which injects the pores of palæozoic Crinoids, can be any other -than an original deposition, allied in the mode of its formation, -to the serpentine, pyroxene, and other minerals which have -injected the Laurentian Eozoon, and the serpentine and -glauconite, which in a similar manner fill Tertiary and recent -shells."</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_30" id="Footnote_30"></a><a href="#FNanchor_30"><span class="label">[AD]</span></a> <i>Journ. für Prakt. Chemie</i>, Bd. 106 (Erster Jahrgang, 1869), p. -356.</p> -</div> - - -<p class="center">(C.) <span class="smcap">Various Minerals filling Cavities of Fossils in the -Laurentian.</span></p> - -<div class="blockquot"> - -<p>The following on this subject is from a memoir by Dr. Hunt -in the <i>Twenty-first Report of the Regents of the University of -New York</i>, 1874:—</p> - -<p>"Recent investigations have shown that in some cases the -dissemination of certain of these minerals through the crystalline -limestones is connected with organic forms. The observations -of Dr. Dawson and myself on the Eozoon Canadense -showed that certain silicates, namely serpentine, pyroxene, and -loganite, had been deposited in the cells and chambers left -vacant by the disappearance of the animal matter from the -calcareous skeleton of the foraminiferous organism; so that -when this calcareous portion is removed by an acid there -remains a coherent mass, which is a cast of the soft parts of -<span class="pagenum"><a name="Page_124" id="Page_124">« 124 »</a></span> -the animal, in which, not only the chambers and connecting -canals, but the minute tubuli and pores are represented by -solid mineral silicates. It was shown that this process must -have taken place immediately after the death of the animal, -and must have depended on the deposition of these silicates -from the waters of the ocean.</p> - -<p>"The train of investigation thus opened up, has been pursued -by Dr. Gümbel, Director of the Geological Survey of Bavaria, -who, in a recent remarkable memoir presented to the -Royal Society of that country, has detailed his results.</p> - -<p>"Having first detected a fossil identical with the Canadian -Eozoon (together with several other curious microscopic -organic forms not yet observed in Canada), replaced by serpentine -in a crystalline limestone from the primitive group of -Bavaria, which he identified with the Laurentian system of -this country, he next discovered a related organism, to which -he has given the name of Eozoon Bavaricum. This occurs in a -crystalline limestone belonging to a series of rocks more -recent than the Laurentian, but older than the Primordial -zone of the Lower Silurian, and designated by him the -Hercynian clay slate series, which he conceives may represent -the Cambrian system of Great Britain, and perhaps correspond -to the Huronian series of Canada and the United -States. The cast of the soft parts of this new fossil is, according -to Gümbel, in part of serpentine, and in part of hornblende.</p> - -<p>"His attention was next directed to the green hornblende -(pargasite) which occurs in the crystalline limestone of Pargas -in Finland, and remains when the carbonate of lime is dissolved -as a coherent mass closely resembling that left by the irregular -and acervuline forms of Eozoon. The calcite walls also -sometimes show casts of tubuli…. A white mineral, -probably scapolite was found to constitute some tubercles -associated with the pargasite, and the two mineral species -were in some cases united in the same rounded grain.</p> - -<p>"Similar observations were made by him upon specimens of -coccolite or green pyroxene, occurring in rounded and wrinkled -grains in a Laurentian limestone from New York. These, -<span class="pagenum"><a name="Page_125" id="Page_125">« 125 »</a></span> -according to Gümbel, present the same connecting cylinders -and branching stems as the pargasite, and are by him supposed -to have been moulded in the same manner…. Very -beautiful evidences of the same organic structure consisting -of the casts of tubuli and their ramifications, were also observed -by Gümbel in a purely crystalline limestone, enclosing -granules of chondrodite, hornblende, and garnet, from Boden -in Saxony. Other specimens of limestone, both with and -without serpentine and chondrodite, were examined without -exhibiting any traces of these peculiar forms; and these -negative results are justly deemed by Gümbel as going to -prove that the structure of the others is really, like that of -Eozoon, the result of the intervention of organic forms. -Besides the minerals observed in the replacing substance of -Eozoon in Canada, viz., serpentine, pyroxene, and loganite, -Gümbel adds chondrodite, hornblende, scapolite, and probably -also pyrallolite, quartz, iolite, and dichroite."</p> -</div> - - -<p class="center">(D.) <span class="smcap">Glauconites.</span></p> - -<div class="blockquot"> - -<p>The following is from a paper by Dr. Hunt in the <i>Report of -the Survey of Canada</i> for 1866:—</p> - -<p>"In connection with the Eozoon it is interesting to examine -more carefully into the nature of the matters which have been -called glauconite or green-sand. These names have been -given to substances of unlike composition, which, however, -occur under similar conditions, and appear to be chemical -deposits from water, filling cavities in minute fossils, or -forming grains in sedimentary rocks of various ages. Although -greenish in colour, and soft and earthy in texture, it -will be seen that the various glauconites differ widely in -composition. The variety best known, and commonly regarded -as the type of the glauconites, is that found in the green-sand of -Cretaceous age in New Jersey, and in the Tertiary of Alabama; -the glauconite from the Lower Silurian rocks of the Upper -Mississippi is identical with it in composition. Analysis -shows these glauconites to be essentially hydrous silicates of -protoxyd of iron, with more or less alumina, and small but -<span class="pagenum"><a name="Page_126" id="Page_126">« 126 »</a></span> -variable quantities of magnesia, besides a notable amount of -potash. This alkali is, however, sometimes wanting, as appears -from the analysis of a green-sand from Kent in England, -by that careful chemist, the late Dr. Edward Turner, and in -another examined by Berthier, from the <i>calcaire grossier</i>, near -Paris, which is essentially a serpentine in composition, being -a hydrous silicate of magnesia and protoxyd of iron. A comparison -of these last two will show that the loganite, which -fills the ancient Foraminifer of Burgess, is a silicate nearly -related in composition.</p> - -<p>I. Green-sand from the <i>calcaire grossier</i>, near Paris. -Berthier (cited by Beudant, <i>Mineralogie</i>, ii., 178).</p> - -<p>II. Green-sand from Kent, England. Dr. Edward Turner -(cited by Rogers, Final Report, Geol. N. Jersey, page 206).</p> - -<p>III. Loganite from the Eozoon of Burgess.</p> - -<p>IV. Green-sand, Lower Silurian; Red Bird, Minnesota.</p> - -<p>V. Green-sand, Cretaceous, New Jersey.</p> - -<p>VI. Green-sand, Lower Silurian, Orleans Island.</p> - -<p>The last four analyses are by myself.</p> -</div> - -<table class="spc2" summary="analyses"> -<tr> - <td></td> - <td class="center">I.</td> - <td class="center">II.</td> - <td class="center">III.</td> - <td class="center">IV.</td> - <td class="center">V.</td> - <td class="center">VI.</td> - <td rowspan="8"></td> -</tr> -<tr> - <td class="tdl">Silica</td> - <td class="tdr">40·0</td> - <td class="tdr">48·5</td> - <td class="tdr">35·14</td> - <td class="tdr">46·58</td> - <td class="tdr">50·70</td> - <td class="tdr">50·7</td> -</tr> -<tr> - <td class="tdl">Protoxyd of iron</td> - <td class="tdr">24·7</td> - <td class="tdr">22·0</td> - <td class="tdr">8·60</td> - <td class="tdr">20·61</td> - <td class="tdr">22·50</td> - <td class="tdr">8·6</td> -</tr> -<tr> - <td class="tdl">Magnesia</td> - <td class="tdr">16·6</td> - <td class="tdr">3·8</td> - <td class="tdr">31·47</td> - <td class="tdr">1·27</td> - <td class="tdr">2·16</td> - <td class="tdr">3·7</td> -</tr> -<tr> - <td class="tdl">Lime</td> - <td class="tdr">3·3</td> - <td class="tdr">....</td> - <td class="tdr">....</td> - <td class="tdr">2·49</td> - <td class="tdr">1·11</td> - <td class="tdr">....</td> -</tr> -<tr> - <td class="tdl">Alumina</td> - <td class="tdr">1·7</td> - <td class="tdr">17·0</td> - <td class="tdr">10·15</td> - <td class="tdr">11·45</td> - <td class="tdr">8·03</td> - <td class="tdr">19·8</td> -</tr> -<tr> - <td class="tdl">Potash</td> - <td class="tdr">....</td> - <td class="tdr">traces.</td> - <td class="tdr">....</td> - <td class="tdr">6·96</td> - <td class="tdr">5·80</td> - <td class="tdr">8·2</td> -</tr> -<tr> - <td class="tdl">Soda</td> - <td class="tdr">....</td> - <td class="tdr">....</td> - <td class="tdr">....</td> - <td class="tdr">·98</td> - <td class="tdr">·75</td> - <td class="tdr">·5</td> -</tr> -<tr> - <td class="tdl">Water</td> - <td class="tdr">12·6</td> - <td class="tdr">7·0</td> - <td class="tdr">14·64</td> - <td class="tdr">9·66</td> - <td class="tdr">8·95</td> - <td class="tdr">8·5</td> -</tr> -<tr> - <td></td> - <td class="tdr">——</td> - <td class="tdr">——</td> - <td class="tdr">——</td> - <td class="tdr">——</td> - <td class="tdr">——</td> - <td class="tdr">——</td> - <td></td> -</tr> -<tr> - <td></td> - <td class="tdr">98·9</td> - <td class="tdr">98·3</td> - <td class="tdr">100·00</td> - <td class="tdr">100·00</td> - <td class="tdr">100·00</td> - <td class="tdr">100·0</td> - <td style="padding-left:0;">"</td> -</tr> -</table> - -<div class="bbox2 fig_center" style="width: 650px;"> -<a name="Plate_VI" id="Plate_VI"></a> -<p class="tdr">Plate VI.</p> - -<div style="width:500px; margin: 0 auto 0 auto;"> -<img src="images/plate_6a.png" width="336" height="252" alt="" /> -<img src="images/plate_6b.png" width="387" height="293" alt="" /> -</div> - -<div class="cap_left">From a Photo. by Weston.</div> -<div class="cap_right">Vincent Brooks, Day & Son Lith.</div> - -<p class="clear caption3" style="padding-top: 9px;">CANAL SYSTEM OF EOZOON.</p> - -<p class="cap_center2">SLICES OF THE FOSSIL (MAGNIFIED.)</p> - -<p class="tdr"><i>To face Chap. 6.</i></p> -</div> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_127" id="Page_127">« 127 »</a></span></p> - - - -<p class="caption2"><a name="CHAPTER_VI" id="CHAPTER_VI">CHAPTER VI.</a><br /> - -CONTEMPORARIES AND SUCCESSORS OF EOZOON.</p> - - -<p class="p0"><span class="smcap">The</span> name Eozoon, or Dawn-animal, raises the -question whether we shall ever know any earlier representative -of animal life. Here I think it necessary to -explain that in suggesting the name Eozoon for the -earliest fossil, and Eozoic for the formation in which it -is contained, I had no intention to affirm that there -may not have been precursors of the Dawn-animal. -By the similar term, Eocene, Lyell did not mean to -affirm that there may not have been modern types in -the preceding geological periods: and so the dawn -of animal life may have had its gray or rosy breaking -at a time long anterior to that in which Eozoon built its -marble reefs. When the fossils of this early auroral -time shall be found, it will not be hard to invent appropriate -names for them. There are, however, two -reasons that give propriety to the name in the present -state of our knowledge. One is, that the Lower Laurentian -rocks are absolutely the oldest that have yet -come under the notice of geologists, and at the present -moment it seems extremely improbable that any older -sediments exist, at least in a condition to be recognised -as such. The other is that Eozoon, as a member of -<span class="pagenum"><a name="Page_128" id="Page_128">« 128 »</a></span> -the group Protozoa, of gigantic size and comprehensive -type, and oceanic in its habitat, is as likely as -any other creature that can be imagined to have been -the first representative of animal life on our planet. -Vegetable life may have preceded it, nay probably did -so by at least one great creative æon, and may have -accumulated previous stores of organic matter; but if -any older forms of animal life existed, it is certain at -least that they cannot have belonged to much simpler -or more comprehensive types. It is also to be observed -that such forms of life, if they did exist, may -have been naked protozoa, which may have left no -sign of their existence except a minute trace of carbonaceous -matter, and perhaps not even this.</p> - -<p>But if we do not know, and perhaps we are not -likely to know, any animals older than Eozoon, may -we not find traces of some of its contemporaries, -either in the Eozoon limestones themselves, or other -rocks associated with them? Here we must admit -that a deep sea Foraminiferal limestone may give a -very imperfect indication of the fauna of its time. A -dredger who should have no other information as to -the existing population of the world, except what he -could gather from the deposits formed under several -hundred fathoms of water, would necessarily have very -inadequate conceptions of the matter. In like manner -a geologist who should have no other information as -to the animal life of the Mesozoic ages than that furnished -by some of the thick beds of white chalk -might imagine that he had reached a period when the -<span class="pagenum"><a name="Page_129" id="Page_129">« 129 »</a></span> -simplest kinds of protozoa predominated over all other -forms of life; but this impression would at once be -corrected by the examination of other deposits of the -same age: so our inferences as to the life of the Laurentian -from the contents of its oceanic limestones -may be very imperfect, and it may yet yield other and -various fossils. Its possibilities are, however, limited -by the fact that before we reach this great depth in -the earth’s crust, we have already left behind in much -newer formations all traces of animal life except a few -of the lower forms of aquatic invertebrates; so that we -are not surprised to find only a limited number of -living things, and those of very low type. Do we -then know in the Laurentian even a few distinct -species, or is our view limited altogether to Eozoon -Canadense? In answering this question we must bear -in mind that the Laurentian itself was of vast duration, -and that important changes of life may have -taken place even between the deposition of the Eozoon -limestones and that of those rocks in which we find -the comparatively rich fauna of the Primordial age. -This subject was discussed by the writer as early as -1865, and I may repeat here what could be said in -relation to it at that time:—</p> - -<p>"In connection with these remarkable remains, it -appeared desirable to ascertain, if possible, what share -these or other organic structures may have had in the -accumulation of the limestones of the Laurentian -series. Specimens were therefore selected by Sir W. -E. Logan, and slices were prepared under his direction. -<span class="pagenum"><a name="Page_130" id="Page_130">« 130 »</a></span> -On microscopic examination, a number of these -were found to exhibit merely a granular aggregation -of crystals, occasionally with particles of graphite and -other foreign minerals, or a laminated mixture of -calcareous and other matters, in the manner of some -more modern sedimentary limestones. Others, however, -were evidently made up almost entirely of fragments -of Eozoon, or of mixtures of these with other -calcareous and carbonaceous fragments which afford -more or less evidence of organic origin. The contents -of these organic limestones may be considered under -the following heads:—</p> - -<p>1. Remains of Eozoon.</p> - -<p>2. Other calcareous bodies, probably organic.</p> - -<p>3. Objects imbedded in the serpentine.</p> - -<p>4. Carbonaceous matters.</p> - -<p>5. Perforations, or worm-burrows.</p> - -<p>"1. The more perfect specimens of Eozoon do not -constitute the mass of any of the larger specimens in -the collection of the Survey; but considerable portions -of some of them are made up of material of similar -minute structure, destitute of lamination, and irregularly -arranged. Some of this material gives the impression -that there may have been organisms similar -to Eozoon, but growing in an irregular or acervuline -manner without lamination. Of this, however, I -cannot be certain; and on the other hand there is -distinct evidence of the aggregation of fragments of -Eozoon in some of these specimens. In some they -<span class="pagenum"><a name="Page_131" id="Page_131">« 131 »</a></span> -constitute the greater part of the mass. In others -they are embedded in calcareous matter of a different -character, or in serpentine or granular pyroxene. In -most of the specimens the cells of the fossils are more -or less filled with these minerals; and in some instances -it would appear that the calcareous matter of -fragments of Eozoon has been in part replaced by serpentine."</p> - -<p>"2. Intermixed with the fragments of Eozoon above -referred to, are other calcareous matters apparently -fragmentary. They are of various angular and -rounded forms, and present several kinds of structure. -The most frequent of these is a strong lamination -varying in direction according to the position of the -fragments, but corresponding, as far as can be ascertained, -with the diagonal of the rhombohedral cleavage. -This structure, though crystalline, is highly characteristic -of crinoidal remains when preserved in altered -limestones. The more dense parts of Eozoon, destitute -of tubuli, also sometimes show this structure, though -less distinctly. Other fragments are compact and -structureless, or show only a fine granular appearance; -and these sometimes include grains, patches, or fibres -of graphite. In Silurian limestones, fragments of -corals and shells which have been partially infiltrated -with bituminous matter, show a structure like this. -On comparison with altered organic limestones of the -Silurian system, these appearances would indicate that -in addition to the debris of Eozoon, other calcareous -structures, more like those of crinoids, corals, and -<span class="pagenum"><a name="Page_132" id="Page_132">« 132 »</a></span> -shells, have contributed to the formation of the Laurentian -limestones.</p> - -<p>"3. In the serpentine<a name="FNanchor_31" id="FNanchor_31"></a><a href="#Footnote_31" class="fnanchor">[AE]</a> filling the chambers of a -large specimen of Eozoon from Burgess, there are -numerous small pieces of foreign matter; and the -silicate itself is laminated, indicating its sedimentary -nature. Some of the included fragments appear to be -carbonaceous, others calcareous; but no distinct organic -structure can be detected in them. There are, -however, in the serpentine, many minute silicious -grains of a bright green colour, resembling green-sand -concretions; and the manner in which these are -occasionally arranged in lines and groups, suggests the -supposition that they may possibly be casts of the -interior of minute Foraminiferal shells. They may, -however, be concretionary in their origin.</p> - -<div class="footnote"> - -<p><a name="Footnote_31" id="Footnote_31"></a><a href="#FNanchor_31"><span class="label">[AE]</span></a> This is the dark green mineral named loganite by Dr. Hunt.</p> -</div> - -<p>"4. In some of the Laurentian limestones submitted -to me by Sir W. E. Logan, and in others which I collected -some years ago at Madoc, Canada West, there -are fibres and granules of carbonaceous matter, which -do not conform to the crystalline structure, and present -forms quite similar to those which in more modern -limestones result from the decomposition of algæ. -Though retaining mere traces of organic structure, no -doubt would be entertained as to their vegetable origin -if they were found in fossiliferous limestones.</p> - -<p>"5. A specimen of impure limestone from Madoc, -in the collection of the Canadian Geological Survey, -which seems from its structure to have been a finely -<span class="pagenum"><a name="Page_133" id="Page_133">« 133 »</a></span> -laminated sediment, shows perforations of various -sizes, somewhat scalloped at the sides, and filled with -grains of rounded silicious sand. In my own collection -there are specimens of micaceous slate from the -same region, with indications on their weathered surfaces -of similar rounded perforations, having the -aspect of Scolithus, or of worm-burrows.</p> - -<p>"Though the abundance and wide distribution of -Eozoon, and the important part it seems to have acted -in the accumulation of limestone, indicate that it was -one of the most prevalent forms of animal existence in -the seas of the Laurentian period, the non-existence of -other organic beings is not implied. On the contrary, -independently of the indications afforded by the limestones -themselves, it is evident that in order to the -existence and growth of these large Rhizopods, the -waters must have swarmed with more minute animal -or vegetable organisms on which they could subsist. -On the other hand, though this is a less certain inference, -the dense calcareous skeleton of Eozoon may -indicate that it also was liable to the attacks of animal -enemies. It is also possible that the growth of -Eozoon, or the deposition of the serpentine and pyroxene -in which its remains have been preserved, or both, -may have been connected with certain oceanic depths -and conditions, and that we have as yet revealed to us -the life of only certain stations in the Laurentian seas. -Whatever conjectures we may form on these more -problematic points, the observations above detailed -appear to establish the following conclusions:—</p> - -<p><span class="pagenum"><a name="Page_134" id="Page_134">« 134 »</a></span></p> - -<p>“First, that in the Laurentian period, as in subsequent -geological epochs, the Rhizopods were important -agents in the accumulation of beds of limestone; and -secondly, that in this early period these low forms of -animal life attained to a development, in point of magnitude -and complexity, unexampled, in so far as yet -known, in the succeeding ages of the earth’s history. -This early culmination of the Rhizopods is in accordance -with one of the great laws of the succession of -living beings, ascertained from the study of the introduction -and progress of other groups; and, should it -prove that these great Protozoans were really the -dominant type of animals in the Laurentian period, -this fact might be regarded as an indication that in -these ancient rocks we may actually have the records -of the first appearance of animal life on our planet.”</p> - -<p>With reference to the first of the above heads, I -have now to state that it seems quite certain that the -upper and younger portions of the masses of Eozoon -often passed into the acervuline form, and the period -in which this change took place seems to have depended -on circumstances. In some specimens there -are only a few regular layers, and then a heap of irregular -cells. In other cases a hundred or more -regular layers were formed; but even in this case -little groups of irregular cells occurred at certain -points near the surface. This may be seen in plate -III. I have also found some masses clearly not fragmental -which consist altogether of acervuline cells. A -specimen of this kind is represented in <a href="#fig_31">fig. 31</a>. It is -<span class="pagenum"><a name="Page_135" id="Page_135">« 135 »</a></span> -oval in outline, about three inches in length, wholly -made up of rounded or cylindrical cells, the walls of -which have a beautiful tubular structure, but there is -little or no supplemental skeleton. Whether this is -a portion accidentally broken off from the top of a -mass of Eozoon, or a peculiar varietal form, or a distinct -species, it would be difficult to determine. In the -meantime I have described it as a variety, “<i>acervulina</i>,” -of the species Eozoon Canadense.<a name="FNanchor_32" id="FNanchor_32"></a><a href="#Footnote_32" class="fnanchor">[AF]</a> Another -variety also, from Petite Nation, shows extremely thin -laminæ, closely placed together and very massive, and -with little supplemental skeleton. This may be allied -to the last, and may be named variety “<i>minor</i>.”</p> - -<div class="footnote"> - -<p><a name="Footnote_32" id="Footnote_32"></a><a href="#FNanchor_32"><span class="label">[AF]</span></a> <i>Proceedings of Geological Society</i>, 1875.</p> -</div> - -<div class="fig_center" style="width: 371px;"> -<a name="fig_31" id="fig_31"></a> -<img src="images/fig_31.png" width="371" height="266" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 31.</span> <i>Acervuline Variety of Eozoon, St. Pierre.</i></p> - -<p class="cap_center2">(<i>a.</i>) General form, half natural size. (<i>b.</i>) Portion of cellular interior, magnified, -showing the course of the tubuli.</p> -</div> - -<p>All this, however, has nothing to do with the layers -<span class="pagenum"><a name="Page_136" id="Page_136">« 136 »</a></span> -of fragments of Eozoon which are scattered through -the Laurentian limestones. In these the fossil is -sometimes preserved in the ordinary manner, with its -cavities filled with serpentine, and the thicker parts of -the skeleton having their canals filled with this substance. -In this case the chambers may have been -occupied with serpentine before it was broken up. At -St. Pierre there are distinct layers of this kind, from -half an inch to several inches in thickness, regularly -interstratified with the ordinary limestone. In other -layers no serpentine occurs, but the interstices of the -fragments are filled with crystalline dolomite or magnesian -limestone, which has also penetrated the canals; -and there are indications, though less manifest, that -some at least of the layers of pure limestone are composed -of fragmental Eozoon. In the Laurentian limestone -of Wentworth, belonging apparently to the same -band with that of St. Pierre, there are many small -rounded pieces of limestone, evidently the debris of -some older rock, broken up and rounded by attrition. -In some of these fragments the structure of Eozoon -may be plainly perceived. This shows that still older -limestones composed of Eozoon were at that time undergoing -waste, and carries our view of the existence -of this fossil back to the very beginning of the Laurentian.</p> - -<p>With respect to organic fragments not showing the -structure of Eozoon, I have not as yet been able to -refer these to any definite origin. Some of them may -be simply thick portions of the shell of Eozoon with -<span class="pagenum"><a name="Page_137" id="Page_137">« 137 »</a></span> -their pores filled with calcite, so as to present a homogeneous -appearance. Others have much the appearance -of fragments of such Primordial forms as <i>Archæocyathus</i>, -to be described in the sequel; but after much -careful search, I have thus far been unable to say more -than I could say in 1865.</p> - -<div class="fig_center" style="width: 408px;"> -<a name="fig_32-34" id="fig_32-34"></a> -<img src="images/fig_32.png" width="408" height="231" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 32.</span> <i>Archæospherinæ from St. Pierre.</i></p> - -<p class="cap_center2">(<i>a.</i>) Specimens dissolved out by acid. The lower one showing interior septa. -(<i>b.</i>) Specimens seen in section.</p> -</div> - -<div class="fig_center" style="width: 400px;"> -<a name="fig_33" id="fig_33"></a> -<img src="images/fig_33.png" width="213" height="124" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 33.</span> <i>Archæospherinæ from Burgess Eozoon.</i></p> - -<p class="cap_center2">Magnified.</p> -</div> - -<p><span class="pagenum"><a name="Page_138" id="Page_138">« 138 »</a></span></p> - -<div class="fig_center" style="width: 400px;"> -<a name="fig_34" id="fig_34"></a> -<img src="images/fig_34.png" width="347" height="381" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 34.</span> <i>Archæospherinæ from Wentworth Limestone.</i></p> - -<p class="cap_center2">Magnified.</p> -</div> - -<p>It is different, however, with the round cells infiltrated -with serpentine and with the silicious grains -included in the loganite. I have already referred to -and figured (<a href="#fig_18">fig. 18</a>) the remarkable rounded bodies -occurring at Long Lake. I now figure similar bodies -found mixed with fragmental Eozoon and in separate -thin layers at St. Pierre (<a href="#fig_32-34">fig. 32</a>), also some of the -singular grains found in the loganite occupying the -chambers of Eozoon from Burgess (<a href="#fig_33">fig. 33</a>), and a -beaded body set free by acid, with others of irregular -forms, from the limestone of Wentworth (<a href="#fig_34">fig. 34</a>). -All these I think are essentially of the same -nature, namely, chambers originally invested with a -tubulated wall like Eozoon, and aggregated in groups, -<span class="pagenum"><a name="Page_139" id="Page_139">« 139 »</a></span> -sometimes in a linear manner, sometimes spirally, like -those Globigerinæ which constitute the mass of modern -deep-sea dredgings and also of the chalk. These -bodies occur dispersed in the limestone, arranged in -thin layers parallel to the bedding or sometimes in the -large chamber-cavities of Eozoon. They are so variable -in size and form that it is not unlikely they may -be of different origins. The most probable of these -may be thus stated. First, they may in some cases -be the looser superficial parts of the surface of Eozoon -broken up into little groups of cells. Secondly, they -may be few-celled germs or buds given off from -Eozoon. Thirdly, they may be smaller Foraminifera, -structurally allied to Eozoon, but in habit of growth -resembling those little globe-shaped forms which, as -already stated, abound in chalk and in the modern -ocean. The latter view I should regard as highly -probable in the case of many of them; and I have -proposed for them, in consequence, and as a convenient -name, <i>Archæospherinæ</i>, or ancient spherical animals.</p> - -<p>Carbonaceous matter is rare in the true Eozoon -limestones, and, as already stated, I would refer the -Laurentian graphite or plumbago mainly to plants. -With regard to the worm-burrows referred to in 1865, -there can be no doubt of their nature, but there is -some doubt as to whether the beds that contain them -are really Lower Laurentian. They may be Upper -Laurentian or Huronian. I give here figures of these -burrows as published in 1866<a name="FNanchor_33" id="FNanchor_33"></a><a href="#Footnote_33" class="fnanchor">[AG]</a> (<a href="#fig_35">fig. 35</a>). The rocks -which contain them hold also fragments of Eozoon, -and are not known to contain other fossils.</p> - -<div class="footnote"> - -<p><a name="Footnote_33" id="Footnote_33"></a><a href="#FNanchor_33"><span class="label">[AG]</span></a> <i>Journal of Geological Society.</i></p> - -<p><span class="pagenum"><a name="Page_140" id="Page_140">« 140 »</a></span></p> -</div> - -<div class="fig_center" style="width: 400px;"> -<a name="fig_35" id="fig_35"></a> -<img src="images/fig_35.png" width="297" height="220" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 35.</span> <i>Annelid Burrows, Laurentian or Huronian.</i></p> - -<p class="cap_hang2">Fig 1. <i>Transverse section of Worm-burrow</i>—magnified, as a transparent object. -(<i>a.</i>) Calcareo-silicious rock. (<i>b.</i>) Space filled with calcareous spar. (<i>c.</i>) -Sand agglutinated and stained black. (<i>d.</i>) Sand less agglutinated and uncoloured. -Fig. 2. <i>Transverse section of Worm-burrow on weathered surface</i>, -natural size. <a href="#fig_3">Fig. 3</a>. <i>The same</i>, magnified.</p> -</div> - -<p>If we now turn to other countries in search of contemporaries -of Eozoon, I may refer first to some specimens -found by my friend Dr. Honeyman at Arisaig, in -Nova Scotia, in beds underlying the Silurian rocks -of that locality, but otherwise of uncertain age. I do -not vouch for them as Laurentian, and if of that age -they seem to indicate a species distinct from that of -Canada proper. They differ in coarser tubulation, -and in their canals being large and beaded, and less -divergent. I proposed for these specimens, in some -notes contributed to the survey of Canada, the name -<i>Eozoon Acadianum</i>.</p> - -<p>Dr. Gümbel, the Director of the Geological Survey -<span class="pagenum"><a name="Page_141" id="Page_141">« 141 »</a></span> -of Bavaria, is one of the most active and widely informed -of European geologists, combining European -knowledge with an extensive acquaintance with the -larger and in some respects more typical areas of the -older rocks in America, and stratigraphical geology -with enthusiastic interest in the microscopic structures -of fossils. He at once and in a most able manner took -up the question of the application of the discoveries -in Canada to the rocks of Bavaria. The spirit in -which he did so may be inferred from the following -extract:—</p> - -<p>"The discovery of organic remains in the crystalline -limestones of the ancient gneiss of Canada, for which -we are indebted to the researches of Sir William -Logan and his colleagues, and to the careful microscopic -investigations of Drs. Dawson and Carpenter, -must be regarded as opening a new era in geological -science.</p> - -<p>"This discovery overturns at once the notions -hitherto commonly entertained with regard to the -origin of the stratified primary limestones, and their -accompanying gneissic and quartzose strata, included -under the general name of primitive crystalline schists. -It shows us that these crystalline stratified rocks, of -the so-called primary system, are only a backward -prolongation of the chain of fossiliferous strata; the -elements of which were deposited as oceanic sediment, -like the clay-slates, limestones, and sandstones of the -palæozoic formations, and under similar conditions, -though at a time far more remote, and more favourable -<span class="pagenum"><a name="Page_142" id="Page_142">« 142 »</a></span> -to the generation of crystalline mineral compounds.</p> - -<p>"In this discovery of organic remains in the primary -rocks, we hail with joy the dawn of a new epoch in -the critical history of these earlier formations. Already -in its light, the primeval geological time is -seen to be everywhere animated, and peopled with -new animal forms of whose very existence we had -previously no suspicion. Life, which had hitherto -been supposed to have first appeared in the Primordial -division of the Silurian period, is now seen to be -immeasurably lengthened beyond its former limit, and -to embrace in its domain the most ancient known -portions of the earth’s crust. It would almost seem -as if organic life had been awakened simultaneously -with the solidification of the earth’s crust.</p> - -<p>"The great importance of this discovery cannot be -clearly understood, unless we first consider the various -and conflicting opinions and theories which had -hitherto been maintained concerning the origin of -these primary rocks. Thus some, who consider them -as the first-formed crust of a previously molten globe, -regard their apparent stratification as a kind of concentric -parallel structure, developed in the progressive -cooling of the mass from without. Others, while admitting -a similar origin of these rocks, suppose their -division into parallel layers to be due, like the lamination -of clay-slates, to lateral pressure. If we admit -such views, the igneous origin of schistose rocks becomes -conceivable, and is in fact maintained by many.</p> - -<p><span class="pagenum"><a name="Page_143" id="Page_143">« 143 »</a></span></p> - -<p>"On the other hand, we have the school which, while -recognising the sedimentary origin of these crystalline -schists, supposes them to have been metamorphosed at -a later period; either by the internal heat, acting in the -deeply buried strata; by the proximity of eruptive -rocks; or finally, through the agency of permeating -waters charged with certain mineral salts.</p> - -<p>“A few geologists only have hitherto inclined to the -opinion that these crystalline schists, while possessing -real stratification, and sedimentary in their origin, -were formed at a period when the conditions were -more favourable to the production of crystalline materials -than at present. According to this view, the -crystalline structure of these rocks is an original condition, -and not one superinduced at a later period by -metamorphosis. In order, however, to arrange and -classify these ancient crystalline rocks, it becomes -necessary to establish by superposition, or by other -evidence, differences in age, such as are recognised in -the more recent stratified deposits. The discovery of -similar organic remains, occupying a determinate position -in the stratification, in different and remote -portions of these primitive rocks, furnishes a powerful -argument in favour of the latter view, as opposed to -the notion which maintains the metamorphic origin of -the various minerals and rocks of these ancient formations; -so that we may regard the direct formation of -these mineral elements, at least so far as these fossiliferous -primary limestones are concerned, as an established -fact.”</p> - -<p><span class="pagenum"><a name="Page_144" id="Page_144">« 144 »</a></span></p> - -<p>His first discovery is thus recorded, in terms which -show the very close resemblance of the Bavarian and -Canadian Eozoic.</p> - -<p>"My discovery of similar organic remains in the -serpentine-limestone from near Passau was made in -1865, when I had returned from my geological labours -of the summer, and received the recently published -descriptions of Messrs. Logan, Dawson, etc. Small -portions of this rock, gathered in the progress of -the Geological Survey in 1854, and ever since preserved -in my collection, having been submitted to -microscopic examination, confirmed in the most brilliant -manner the acute judgment of the Canadian geologists, -and furnished palæontological evidence that, -notwithstanding the great distance which separates -Canada from Bavaria, the equivalent primitive rocks -of the two regions are characterized by similar organic -remains; showing at the same time that the -law governing the definite succession of organic life -on the earth is maintained even in these most ancient -formations. The fragments of serpentine-limestone, -or ophicalcite, in which I first detected the existence -of Eozoon, were like those described in Canada, in -which the lamellar structure is wanting, and offer only -what Dr. Carpenter has called an acervuline structure. -For further confirmation of my observations, I deemed -it advisable, through the kindness of Sir Charles Lyell, -to submit specimens of the Bavarian rock to the examination -of that eminent authority, Dr. Carpenter, who, -without any hesitation, declared them to contain Eozoon.</p> - -<p><span class="pagenum"><a name="Page_145" id="Page_145">« 145 »</a></span></p> - -<p>"This fact being established, I procured from the -quarries near Passau as many specimens of the limestone -as the advanced season of the year would permit; -and, aided by my diligent and skillful assistants, -Messrs. Reber and Schwager, examined them by the -methods indicated by Messrs. Dawson and Carpenter. -In this way I soon convinced myself of the general -similarity of our organic remains with those of Canada. -Our examinations were made on polished sections and -in portions etched with dilute nitric acid, or, better, -with warm acetic acid. The most beautiful results -were however obtained by etching moderately thin -sections, so that the specimens may be examined at -will either by reflected or transmitted light.</p> - -<p>"The specimens in which I first detected Eozoon -came from a quarry at Steinhag, near Obernzell, on -the Danube, not far from Passau. The crystalline -limestone here forms a mass from fifty to seventy -feet thick, divided into several beds, included in the -gneiss, whose general strike in this region is N.W., -with a dip of 40°-60° N.E. The limestone strata of -Steinhag have a dip of 45° N.E. The gneiss of this -vicinity is chiefly grey, and very silicious, containing -dichroite, and of the variety known as dichroite-gneiss; -and I conceive it to belong, like the gneiss of -Bodenmais and Arber, to that younger division of the -primitive gneiss system which I have designated as -the Hercynian gneiss formation; which, both to the -north, between Tischenreuth and Mahring, and to the -south on the north-west of the mountains of Ossa, -<span class="pagenum"><a name="Page_146" id="Page_146">« 146 »</a></span> -is immediately overlaid by the mica-slate formation. -Lithologically, this newer division of the gneiss is -characterized by the predominance of a grey variety, -rich in quartz, with black magnesian-mica and orthoclase, -besides which a small quantity of oligoclase is -never wanting. A further characteristic of this Hercynian -gneiss is the frequent intercalation of beds of -rocks rich in hornblende, such as hornblende-schist, -amphibolite, diorite, syenite, and syenitic granite, and -also of serpentine and granulite. Beds of granular -limestone, or of calcareous schists are also never altogether -wanting; while iron pyrites and graphite, in -lenticular masses, or in local beds conformable to the -great mass of the gneiss strata, are very generally -present.</p> - -<p>"In the large quarry of Steinhag, from which I first -obtained the Eozoon, the enclosing rock is a grey -hornblendic gneiss, which sometimes passes into a -hornblende-slate. The limestone is in many places -overlaid by a bed of hornblende-schist, sometimes five -feet in thickness, which separates it from the normal -gneiss. In many localities, a bed of serpentine, three -or four feet thick, is interposed between the limestone -and the hornblende-schist; and in some cases a zone, -consisting chiefly of scapolite, crystalline and almost -compact, with an admixture however of hornblende and -chlorite. Below the serpentine band, the crystalline -limestone appears divided into distinct beds, and encloses -various accidental minerals, among which are -reddish-white mica, chlorite, hornblende, tremolite, -<span class="pagenum"><a name="Page_147" id="Page_147">« 147 »</a></span> -chondrodite, rosellan, garnet, and scapolite, arranged -in bands. In several places the lime is mingled with -serpentine, grains or portions of which, often of the -size of peas, are scattered through the limestone with -apparent irregularity, giving rise to a beautiful variety -of ophicalcite or serpentine-marble. These portions, -which are enclosed in the limestone destitute of serpentine, -always present a rounded outline. In one -instance there appears, in a high naked wall of limestone -without serpentine, the outline of a mass of -ophicalcite, about sixteen feet long and twenty-five -feet high, which, rising from a broad base, ends in a -point, and is separated from the enclosing limestone -by an undulating but clearly defined margin, as already -well described by Wineberger. This mass of -ophicalcite recalls vividly a reef-like structure. Within -this and similar masses of ophicalcite in the crystalline -limestone, there are, so far as my observations in -1854 extend, no continuous lines or concentric layers -of serpentine to be observed, this mineral being always -distributed in small grains and patches. The -few apparently regular layers which may be observed -are soon interrupted, and the whole aggregation is -irregular."</p> - -<p>It will be observed that this acervuline Eozoon of -Steinhag appears to exist in large reefs, and that in -its want of lamination it differs from the Canadian -examples. In fossils of low organization, like Foraminifera, -such differences are often accidental and compatible -with specific unity, but yet there may be a -<span class="pagenum"><a name="Page_148" id="Page_148">« 148 »</a></span> -difference specifically in the Bavarian Eozoon as compared -with the Canadian.</p> - -<p>Gümbel also found in the Finnish and Bavarian -limestones knotted chambers, like those of Wentworth -above mentioned (<a href="#fig_36">fig. 36</a>), which he regards as belonging -to some other organism than Eozoon; and -flocculi having tubes, pores, and reticulations which -would seem to point to the presence of structures -akin to sponges or possibly remains of seaweeds. -These observations Gümbel has extended into other -localities in Bavaria and Bohemia, and also in Silesia -and Sweden, establishing the existence of Eozoon -fossils in all the Laurentian limestones of the middle -and north of Europe.</p> - -<div class="fig_center" style="width: 268px;"> -<a name="fig_36" id="fig_36"></a> -<img src="images/fig_36.png" width="268" height="95" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 36.</span> <i>Archæospherinæ from Pargas in Finland.</i> (<i>After Gümbel.</i>)</p> -<p class="cap_center2">Magnified.</p> -</div> - -<p>Gümbel has further found in beds overlying the -older Eozoic series, and probably of the same age with -the Canadian Huronian, a different species of Eozoon, -with smaller and more contracted chambers, and still -finer and more crowded canals. This, which is to be -regarded as a distinct species, or at least a well-marked -varietal form, he has named <i>Eozoon Bavaricum</i> (<a href="#fig_37">fig. 37</a>). -Thus this early introduction of life is not peculiar -to that old continent which we sometimes call the New -<span class="pagenum"><a name="Page_149" id="Page_149">« 149 »</a></span> -World, but applies to Europe as well, and Europe has -furnished a successor to Eozoon in the later Eozoic or -Huronian period. In rocks of this age in America, -after long search and much slicing of limestones, I -have hitherto failed to find any decided organic remains -other than the Tudor and Madoc specimens of -Eozoon. If these are really Huronian and not Laurentian, -the Eozoon from this horizon does not sensibly -differ from that of the Lower Laurentian. The curious -limpet-like objects from Newfoundland, discovered by -Murray, and described by Billings,<a name="FNanchor_34" id="FNanchor_34"></a><a href="#Footnote_34" class="fnanchor">[AH]</a> under the name -<i>Aspidella</i>, are believed to be Huronian, but they have -no connection with Eozoon, and therefore need not -detain us here.</p> - -<div class="footnote"> - -<p><a name="Footnote_34" id="Footnote_34"></a><a href="#FNanchor_34"><span class="label">[AH]</span></a> <i>Canadian Naturalist</i>, 1871.</p> -</div> - -<div class="fig_center" style="width: 318px;"> -<a name="fig_37" id="fig_37"></a> -<img src="images/fig_37.png" width="318" height="159" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 37.</span> <i>Section of Eozoon Bavaricum, with Serpentine, from the -Crystalline Limestone of the Hercynian primitive Clay-state Formation -at Hohenberg; 25 diameters.</i></p> - -<p class="cap_center2">(<i>a.</i>) Sparry carbonate of lime. (<i>b.</i>) Cellular carbonate of lime. (<i>c.</i>) System of -tubuli. (<i>d.</i>) Serpentine replacing the coarser ordinary variety. (<i>e.</i>) Serpentine -and hornblende replacing the finer variety, in the very much contorted -portions.</p> -</div> - -<p>Leaving the Eozoic age, we find ourselves next in the -Primordial or Cambrian, and here we discover the sea -<span class="pagenum"><a name="Page_150" id="Page_150">« 150 »</a></span> -already tenanted by many kinds of crustaceans and -shell-fishes, which have been collected and described -by palæontologists in Bohemia, Scandinavia, Wales, -and North America;<a name="FNanchor_35" id="FNanchor_35"></a><a href="#Footnote_35" class="fnanchor">[AI]</a> curiously enough, however, the -rocks of this age are not so rich in Foraminifera as -those of some succeeding periods. Had this primitive -type played out its part in the Eozoic and exhausted -its energies, and did it remain in abeyance in the -Primordial age to resume its activity in the succeeding -times? It is not necessary to believe this. The -geologist is familiar with the fact, that in one formation -he may have before him chiefly oceanic and deep-sea -deposits, and in another those of the shallower -waters, and that alternations of these may, in the same -age or immediately succeeding ages, present very different -groups of fossils. Now the rocks and fossils of -the Laurentian seem to be oceanic in character, while -the Huronian and early Primordial rocks evidence -great disturbances, and much coarse and muddy sediment, -such as that found in shallows or near the land. -They abound in coarse conglomerates, sandstones and -thick beds of slate or shale, but are not rich in limestones, -which do not in the parts of the world yet explored -regain their importance till the succeeding Siluro-Cambrian -age. No doubt there were, in the Primordial, -deep-sea areas swarming with Foraminifera, the -successors of Eozoon; but these are as yet unknown -or little known, and our known Primordial fauna is -chiefly that of the shallows. Enlarged knowledge may -thus bridge over much of the apparent gap in the life -of these two great periods.</p> - -<div class="footnote"> - -<p><a name="Footnote_35" id="Footnote_35"></a><a href="#FNanchor_35"><span class="label">[AI]</span></a> Barrande, Angelin, Hicks, Hall, Billings, etc.</p> - -<p><span class="pagenum"><a name="Page_151" id="Page_151">« 151 »</a></span></p> -</div> - -<p>Only as yet on the coast of Labrador and neighbouring -parts of North America, and in rocks that -were formed in seas that washed the old Laurentian -rocks, in which Eozoon was already as fully sealed up -as it is at this moment, do we find Protozoa which -can claim any near kinship to the proto-foraminifer. -These are the fossils of the genus <i>Archæocyathus</i>—“ancient -cup-sponges, or cup-foraminifers,” which -have been described in much detail by Mr. Billings -in the reports of the Canadian Survey. Mr. Billings -regards them as possibly sponges, or as intermediate -between these and Foraminifera, and the silicious -spicules found in some of them justify this view, unless -indeed, as partly suspected by Mr. Billings, these -belong to true sponges which may have grown along -with Archæocyathus or attached to it. Certain it is, -however, that if allied to sponges, they are allied also -to Foraminifera, and that some of them deviate altogether -from the sponge type and become calcareous -chambered bodies, the animals of which can have -differed very little from those of the Laurentian Eozoon. -It is to these calcareous Foraminiferal species that I -shall at present restrict my attention. I give a few -figures, for which I am indebted to Mr. Billings, of -three of his species (figs. 38 to 40), with enlarged -drawings of the structures of one of them which has -the most decidedly foraminiferal characters.</p> - -<p><span class="pagenum"><a name="Page_152" id="Page_152">« 152 »</a></span></p> - -<div class="fig_center" style="width: 312px;"> -<a name="fig_38-39-40" id="fig_38-39-40"></a> -<img src="images/fig_38.png" width="312" height="459" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 38.</span> <i>Archæocyathus Minganensis—a Primordial Protozoon.</i> -(<i>After Billings.</i>)</p> - -<p class="cap_hang">(<i>a.</i>) Pores of the inner wall.</p> -</div> - -<p><span class="pagenum"><a name="Page_153" id="Page_153">« 153 »</a></span></p> - -<div class="fig_center" style="width: 138px;"> -<a name="fig_39" id="fig_39"></a> -<img src="images/fig_39.png" width="138" height="190" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 39.</span> <i>Archæocyathus profundus—showing the base of attachment -and radiating chambers.</i> (<i>After Billings.</i>)</p> -</div> - -<div class="fig_center" style="width: 416px;"> -<a name="fig_40" id="fig_40"></a> -<img src="images/fig_40.png" width="416" height="343" alt="" /> -<p class="cap_hang"><span class="smcap">Fig. 40.</span> <i>Archæocyathus Atlanticus—showing outer surface and -longitudinal and transverse sections.</i> (<i>After Billings.</i>)</p> -</div> - -<p><span class="pagenum"><a name="Page_154" id="Page_154">« 154 »</a></span></p> - -<div class="fig_center" style="width: 406px;"> -<a name="fig_41" id="fig_41"></a> -<img src="images/fig_41.png" width="406" height="311" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 41.</span> <i>Structures of Archæocyathus Profundus.</i></p> - -<p class="cap_center2">(<i>a.</i>) Lower acervuline portion. (<i>b.</i>) Upper portion, with three of the radiating -laminæ. (<i>c.</i>) Portion of lamina with pores and thickened part with canals. -In figs. <i>a</i> and <i>b</i> the calcareous part is unshaded.</p> -</div> - -<p>To understand Archæocyathus, let us imagine an -inverted cone of carbonate of lime from an inch or -two to a foot in length, and with its point buried in -the mud at the bottom of the sea, while its open cup -extends upward into the water. The lower part -buried in the soil is composed of an irregular acervuline -network of thick calcareous plates, enclosing -chambers communicating with one another (figs. 40 -and 41 <span class="smcap">A</span>). Above this where the cup expands, its walls -are composed of thin outer and inner plates, perforated -with innumerable holes, and connected with each other -by vertical plates, which are also perforated with round -pores, establishing a communication between the radiating -chambers into which they divide the thickness -of the wall (figs. 38, 39, and 41 <span class="smcap">B</span>). In such a structure -the chambers in the wall of the cup and the -irregular chambers of the base would be filled with -gelatinous animal matter, and the pseudopods would -project from the numerous pores in the inner and -outer wall. In the older parts of the skeleton, the -<span class="pagenum"><a name="Page_155" id="Page_155">« 155 »</a></span> -structure is further complicated by the formation of -thin transverse plates, irregular in distribution, and -where greater strength is required a calcareous thickening -is added, which in some places shows a canal -system like that of Eozoon (<a href="#fig_41">fig. 41</a>, <span class="smcap">B</span>, <span class="smcap">C</span>).<a name="FNanchor_36" id="FNanchor_36"></a><a href="#Footnote_36" class="fnanchor">[AJ]</a> As compared -with Eozoon, the fossils want its fine perforated -wall, but have a more regular plan of growth. There -are fragments in the Eozoon limestones which may -have belonged to structures like these; and when we -know more of the deep sea of the Primordial, we may -recover true species of Eozoon from it, or may find -forms intermediate between it and Archæocyathus. -In the meantime I know no nearer bond of connection -between Eozoon and the Primordial age than that -furnished by the ancient cup Zoophytes of Labrador, -though I have searched very carefully in the -fossiliferous conglomerates of Cambrian age on the -Lower St. Lawrence, which contain rocks of all the -formations from the Laurentian upwards, often with -characteristic fossils. I have also made sections of -many of the fossiliferous pebbles in these conglomerates -without finding any certain remains of such -organisms, though the fragments of the crusts of some -of the Primordial tribolites, when their tubuli are infiltrated -with dark carbonaceous matter, are so like -the supplemental skeleton of Eozoon, that but for -<span class="pagenum"><a name="Page_156" id="Page_156">« 156 »</a></span> -their forms they might readily be mistaken for it; and -associated with them are broken pieces of other porous -organisms which may belong to Protozoa, though this -is not yet certain.</p> - -<div class="footnote"> - -<p><a name="Footnote_36" id="Footnote_36"></a><a href="#FNanchor_36"><span class="label">[AJ]</span></a> On the whole these curious fossils, if regarded as Foraminifera, -are most nearly allied to the Orbitolites and Dactyloporæ -of the Early Tertiary period, as described by Carpenter.</p> -</div> - -<p>Of all the fossils of the Silurian rocks those -which most resemble Eozoon are the <i>Stromatoporæ</i>, -or “layer-corals,” whose resemblance to the old -Laurentian fossil at once struck Sir William Logan; -and these occur in the earliest great oceanic limestones -which succeed the Primordial period, those -of the Trenton group, in the Siluro-Cambrian. From -this they extend upward as far as the Devonian, appearing -everywhere in the limestones, and themselves -often constituting large masses of calcareous rock. -Our figure (<a href="#fig_42">fig. 42</a>) shows a small example of one of -these fossils; and when sawn asunder or broken -across and weathered, they precisely resemble Eozoon -in general appearance, especially when, as sometimes -happens, their cell-walls have been silicified.</p> - -<div class="fig_center" style="width: 383px;"> -<a name="fig_42" id="fig_42"></a> -<img src="images/fig_42.png" width="383" height="343" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 42.</span> <i>Stromatopora rugosa, Hall—Lower Silurian, Canada.</i> -(<i>After Billings.</i>)</p> - -<p class="cap_center2">The specimen is of smaller size than usual, and is silicified. It is probably -inverted in position, and the concentric marks on the outer surface are due -to concretions of silica.</p> -</div> - -<p>There are, however, different types of these fossils. -The most common, the Stromatoporæ properly so -called, consist of concentric layers of calcareous matter -attached to each other by pillar-like processes, which, -as well as the layers, are made up of little threads of -limestone netted together, or radiating from the tops -and bottoms of the pillars, and forming a very porous -substance. Though they have been regarded as corals -by some, they are more generally believed to be Protozoa; -but whether more nearly allied to sponges or to -Foraminifera may admit of doubt. Some of the more -<span class="pagenum"><a name="Page_157" id="Page_157">« 157 »</a></span> -porous kinds are not very dissimilar from calcareous -sponges, but they generally want true oscula and -pores, and seem better adapted to shield the gelatinous -body of a Foraminifer projecting pseudopods in -search of food, than that of a sponge, living by the -introduction of currents of water. Many of the -denser kinds, however, have their calcareous floors so -solid that they must be regarded as much more nearly -akin to Foraminifers, and some of them have the same -irregular inosculation of these floors observed in Eozoon. -<span class="pagenum"><a name="Page_158" id="Page_158">« 158 »</a></span> -<a href="#fig_43">Figs. 43</a>, <span class="smcap">A</span> to <span class="smcap">D</span>, show portions of species of -this description, in which the resemblance to Eozoon -in structure and arrangement of parts is not remote.</p> - -<div class="fig_center" style="width: 309px;"> -<a name="fig_43" id="fig_43"></a> -<img src="images/fig_43.png" width="309" height="425" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 43.</span> <i>Structures of Stromatopora.</i></p> - -<p class="cap_center2">(<i>a.</i>) Portion of an oblique section magnified, showing laminæ and columns. (<i>b.</i>) -Portion of wall with pores, and crusted on both sides with quartz crystals. -(<i>c.</i>) Thickened portion of wall with canals. (<i>d.</i>) Portion of another specimen, -showing irregular laminæ and pillars.</p> -</div> - -<p>These fossils, however, show no very distinct canal -system or supplemental skeleton, but this also appears -in those forms which have been called Caunopora or -Cœnostroma. In these the plates are traversed by -<span class="pagenum"><a name="Page_159" id="Page_159">« 159 »</a></span> -tubes, or groups of tubes, which in each successive -floor give out radiating and branching canals exactly -like those of Eozoon, though more regularly arranged; -and if we had specimens with the canals infiltrated -with glauconite or serpentine, the resemblance would -be perfect. When, as in figs. 44 and 45 <span class="smcap">A</span>, these canals -are seen on the abraded surface, they appear as little -grooves arranged in stars, which resemble the radiating -plates of corals, but this resemblance is altogether -superficial, and I have no doubt that they are really -foraminiferal organisms. This will appear more distinctly -from the sections in <a href="#fig_45">fig. 45</a> <span class="smcap">B</span>, <span class="smcap">C</span>, which represents -an undescribed species recently found by Mr. -Weston, in the Upper Silurian limestone of Ontario.</p> - -<div> -<a name="fig_44" id="fig_44"></a><a name="fig_45" id="fig_45"></a> - -<table summary="fig 44-45"> -<tr> - <td class="center" style="width:255px"><img src="images/fig_44.png" width="185" height="109" alt="" /></td> - <td class="center" style="width:255px"><img src="images/fig_45.png" width="181" height="134" alt="" /></td> -</tr> -<tr> - <td class="vtop"><p class="cap_center" style="margin-right:12px;"><span class="smcap">Fig. 44.</span> <i>Caunopora planulata, Hall—Devonian; showing the radiating - canals on a weathered surface.</i> (<i>After Hall.</i>)</p></td> - <td><p class="cap_center"><span class="smcap">Fig. 45.</span> <i>Cœnostroma—Guelph Limestone, Upper Silurian, from a - specimen collected by Mr. Weston, showing the canals.</i></p> - <p class="cap_center2">(<i>a.</i>) Surface with canals, natural size. (<i>b.</i>) Vertical section, natural size. (<i>c.</i>) - The same magnified, showing canals and laminæ.</p></td> -</tr> -</table> -</div> - -<p>There are probably many species of these curious -fossils, but their discrimination is difficult, and their -nomenclature confused, so that it would not be profitable -to engage the attention of the reader with it -except in a note. Their state of preservation, however, -is so highly illustrative of that of Eozoon that a -word as to this will not be out of place. They are -<span class="pagenum"><a name="Page_160" id="Page_160">« 160 »</a></span> -sometimes preserved merely by infiltration with calcite -or dolomite, and in this case it is most difficult to -make out their minute structures. Often they appear -merely as concentrically laminated masses which, but -for their mode of occurrence, might be regarded as -mere concretions. In other cases the cell-walls and -pillars are perfectly silicified, and then they form beautiful -microscopic objects, especially when decalcified -with an acid. In still other cases, they are preserved -like Eozoon, the walls being calcareous and the chambers -filled with silica. In this state when weathered -or decalcified they are remarkably like Eozoon, but I -have not met with any having their minute pores and -tubes so well preserved as in some of the Laurentian -fossils. In many of them, however, the growth and -overlapping of the successive amœba-like coats of sarcode -can be beautifully seen, exactly as on the surface -of a decalcified piece of Eozoon. Those in my collection -which most nearly resemble the Laurentian specimens -<span class="pagenum"><a name="Page_161" id="Page_161">« 161 »</a></span> -are from the older part of the Lower Silurian -series; but unfortunately their minute structures are -not well preserved.</p> - -<p>In the Silurian and Devonian ages, these Stromatoporæ -evidently carried out the same function as the -Eozoon in the Laurentian. Winchell tells us that in -Michigan and Ohio single specimens can be found -several feet in diameter, and that they constitute the -mass of considerable beds of limestone. I have myself -seen in Canada specimens a foot in diameter, with a -great number of laminæ. Lindberg<a name="FNanchor_37" id="FNanchor_37"></a><a href="#Footnote_37" class="fnanchor">[AK]</a> has given a most -vivid account of their occurrence in the Isle of Gothland. -He says that they form beds of large irregular -discs and balls, attaining a thickness of five Swedish -feet, and traceable for miles along the coast, and the -individual balls are sometimes a yard in diameter. In -some of them the structure is beautifully preserved. -In others, or in parts of them, it is reduced to a mass -of crystalline limestone. This species is of the Cœnostroma -type, and is regarded by Lindberg as a coral, -though he admits its low type and resemblance to -Protozoa. Its continuous calcareous skeleton he -rightly regards as fatal to its claim to be a true -sponge. Such a fossil, differing as it does in minute -points of structure from Eozoon, is nevertheless probably -allied to it in no very distant way, and a successor -to its limestone-making function. Those which most -nearly approach to Foraminifera are those with thick -and solid calcareous laminæ, and with a radiating canal -<span class="pagenum"><a name="Page_162" id="Page_162">« 162 »</a></span> -system; and one of the most Eozoon-like I have seen, -is a specimen of the undescribed species already mentioned -from the Guelph (Upper Silurian) limestone of -Ontario, collected by Mr. Weston, and now in the -Museum of the Geological Survey. I have attempted -to represent its structures in <a href="#fig_44">fig. 44</a>.</p> - -<div class="footnote"> - -<p><a name="Footnote_37" id="Footnote_37"></a><a href="#FNanchor_37"><span class="label">[AK]</span></a> <i>Transactions of Swedish Academy</i>, 1870.</p> -</div> - -<p>In the rocks extending from the Lower Silurian and -perhaps from the Upper Cambrian to the Devonian -inclusive, the type and function of Eozoon are continued -by the Stromatoporæ, and in the earlier part of -this time these are accompanied by the Archæocyathids, -and by another curious form, more nearly -allied to the latter than to Eozoon, the <i>Receptaculites</i>. -These curious and beautiful fossils, which -sometimes are a foot in diameter, consist, like Archæocyathus, -of an outer and inner coat enclosing a cavity; -but these coats are composed of square plates with -<span class="pagenum"><a name="Page_163" id="Page_163">« 163 »</a></span> -pores at the corners, and they are connected by hollow -pillars passing in a regular manner from the outer to -the inner coat. They have been regarded by Salter as -Foraminifers, while Billings considers their nearest -analogues to be the seed-like germs of some modern -silicious sponges. On the whole, if not Foraminifera, -they must have been organisms intermediate between -these and sponges, and they certainly constitute one of -the most beautiful and complex types of the ancient -Protozoa, showing the wonderful perfection to which -these creatures attained at a very early period. (<a href="#fig_46">Figs. -46, 47, 48.</a>)</p> - -<div class="fig_center" style="width: 400px;"> -<a name="fig_46" id="fig_46"></a> -<img src="images/fig_46.png" width="255" height="240" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 46.</span> <i>Receptaculites, restored.</i> (<i>After Billings.</i>)</p> - -<p class="cap_center2">(<i>a.</i>) Aperture. (<i>b.</i>) Inner wall. (<i>c.</i>) Outer wall. (<i>n.</i>) Nucleus, or primary -chamber. (<i>v.</i>) Internal cavity.</p> - -<a name="fig_47-48" id="fig_47-48"></a> -<img src="images/fig_47.png" width="391" height="290" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 47.</span> <i>Diagram of Wall and Tubes of Receptaculites.</i> (<i>After -Billings.</i>)</p> - -<p class="cap_center2">(<i>b.</i>) Inner wall. (<i>c.</i>) Outer wall. (<i>d.</i>) Section of plates. (<i>e.</i>) Pore of inner wall. -(<i>f.</i>) Canal of inner wall. (<i>g.</i>) Radial stolon. (<i>h.</i>) Cyclical stolon. (<i>k.</i>) -Suture of plates of outer wall.</p> -<br /> - -<img src="images/fig_48.png" width="127" height="152" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 48.</span> <i>Receptaculites, Inner Surface of Outer Wall with the -Stolons remaining on its Surface.</i> (<i>After Billings.</i>)</p> -</div> - -<p><span class="pagenum"><a name="Page_164" id="Page_164">« 164 »</a></span></p> - -<p>I might trace these ancient forms of foraminiferal -life further up in the geological series, and show how -in the Carboniferous there are nummulitic shells conforming -to the general type of Eozoon, and in some -cases making up the mass of great limestones.<a name="FNanchor_38" id="FNanchor_38"></a><a href="#Footnote_38" class="fnanchor">[AL]</a> Further, -in the great chalk series and its allied beds, and -in the Lower Tertiary, there are not only vast foraminiferal -limestones, but gigantic species reminding us of -Stromatopora and Eozoon.<a name="FNanchor_39" id="FNanchor_39"></a><a href="#Footnote_39" class="fnanchor">[AM]</a> Lastly, more diminutive -species are doing similar work on a great scale in the -modern ocean. Thus we may gather up the broken -links of the chain of foraminiferal life, and affirm that -Eozoon has never wanted some representative to uphold -its family and function throughout all the vast lapse -of geological time.</p> - -<div class="footnote"> - -<p><a name="Footnote_38" id="Footnote_38"></a><a href="#FNanchor_38"><span class="label">[AL]</span></a> <i>Fusulina</i>, as recently described by Carpenter, <i>Archæodiscus</i> -of Brady, and the Nummulite recently found in the -Carboniferous of Belgium.</p> -</div> - -<div class="footnote"> - -<p><a name="Footnote_39" id="Footnote_39"></a><a href="#FNanchor_39"><span class="label">[AM]</span></a> <i>Parkeria</i> and <i>Loftusia</i> of Carpenter.</p> - -<p><span class="pagenum"><a name="Page_165" id="Page_165">« 165 »</a></span></p> -</div> - - -<p class="caption3">NOTES TO CHAPTER VI.</p> - -<p class="center">(A.) <span class="smcap">Stromatoporidæ, Etc.</span></p> - -<div class="blockquot"> - -<p>For the best description of Archæocyathus, I may refer to -<i>The Palæozoic Fossils of Canada</i>, by Mr. Billings, vol. i. -There also, and in Mr. Salter’s memoir in <i>The Decades of the -Canadian Survey</i>, will be found all that is known of the structure -of Receptaculites. For the American Stromatoporæ I -may refer to Winchell’s paper in the <i>Proceedings of the -American Association</i>, 1866; to Professor Hall’s Descriptions -of New Species of Fossils from Iowa, <i>Report of the State -Cabinet, Albany</i>, 1872; and to the Descriptions of Canadian -Species by Dr. Nicholson, in his <i>Report on the Palæontology -of Ontario</i>, 1874.</p> - -<p>The genus Stromatopora of Goldfuss was defined by him as -consisting of laminæ of a solid and porous character, alternating -and contiguous, and constituting a hemispherical or sub-globose -mass. In this definition, the porous strata are -really those of the fossil, the alternating solid strata being the -stony filling of the chambers; and the descriptions of subsequent -authors have varied according as, from the state of -preservation of the specimens or other circumstances, the -original laminæ or the filling of the spaces attracted their -attention. In the former case the fossil could be described as -consisting of laminæ made up of interlaced fibrils of calcite, -radiating from vertical pillars which connect the laminæ. In -the latter case, the laminæ, appear as solid plates, separated by -very narrow spaces, and perforated with round vertical holes -representing the connecting pillars. These Stromatoporæ -range from the Lower Silurian to the Devonian, inclusive, and -many species have been described; but their limits are not -very definite, though there are undoubtedly remarkable differences -in the distances of the laminæ and in their texture, and -in the smooth or mammillated character of the masses. Hall’s -genus Stromatocerium belongs to these forms, and D’Orbigny’s -genus Sparsispongia refers to mammillated species, sometimes -with apparent oscula.</p> -</div> - -<p><span class="pagenum"><a name="Page_166" id="Page_166">« 166 »</a></span></p> - -<div class="blockquot"> - -<p>Phillip’s genus Caunopora was formed to receive specimens -with concentric cellular layers traversed by “long vermiform -cylindrical canals;” while Winchell’s genus Cœnostroma includes -species with these vermiform canals arranged in a radiate -manner, diverging from little eminences in the concentric -laminæ. The distinction between these last genera does not -seem to be very clear, and may depend on the state of preservation -of the specimens. A more important distinction -appears to exist between those that have a single vertical canal -from which the subordinate canals diverge, and those that have -groups of such canals.</p> - -<p>Some species of the Cœnostroma group have very dense calcareous -laminæ traversed by the canals; but it does not seem -that any distinction has yet been made between the proper -wall and the intermediate skeleton; and most observers have -been prevented from attending to such structures by the -prevailing idea that these fossils are either corals or sponges, -while the state of preservation of the more delicate tissues is -often very imperfect.</p> -</div> - - -<p class="center">(B.) <span class="smcap">Localities of Eozoon, or of Limestones supposed to -contain it.</span></p> - -<div class="blockquot"> - -<p>In Canada the principal localities of Eozoon Canadense are -at Grenville, Petite Nation, the Calumets Rapids, Burgess, -Tudor, and Madoc. At the two last places the fossil occurs in -beds which may be on a somewhat higher horizon than the -others. Mr. Vennor has recently found specimens which have -the general form of Eozoon, though the minute structure is not -preserved, at Dalhousie, in Lanark Co., Ontario. One specimen -from this place is remarkable from having been mineralized -in part by a talcose mineral associated with serpentine.</p> - -<p>I have examined specimens from Chelmsford, in Massachusetts, -and from Amity and Warren County, New York, the -latter from the collection of Professor D. S. Martin, which -show the canals of Eozoon in a fair state of preservation, -though the specimens are fragmental, and do not show the -laminated structure.</p> -</div> - -<p><span class="pagenum"><a name="Page_167" id="Page_167">« 167 »</a></span></p> - -<div class="blockquot"> - -<p>In European specimens of limestones of Laurentian age, -from Tunaberg and Fahlun in Sweden, and from the Western -Islands of Scotland, I have hitherto failed to recognise the -characteristic structure of the fossil. Connemara specimens -have also failed to afford me any satisfactory results, and -specimens of a serpentine limestone from the Alps, collected -by M. Favre, and communicated to me by Dr. Hunt, though in -general texture they much resemble acervuline Eozoon, do not -show its minute structures.</p> -</div> - -<p><span class="pagenum"><a name="Page_168" id="Page_168">« 168 »</a></span></p> - -<div class="bbox2 fig_center" style="width: 650px;"> -<a name="Plate_VII" id="Plate_VII"></a> -<p class="tdr">Plate VII.</p> - -<div class="fig_center" style="width: 515px;"> -<img src="images/plate_7.png" width="515" height="749" alt="" /> -</div> - -<p><i>Untouched nature-print of part of a large specimen of Eozoon, from -Petite Nation.</i></p> - -<p class="hanging">The lighter portions are less perfect than in the original, owing to the finer -laminæ of serpentine giving way. The dark band at one side is one of the -deep lacunæ or oscula.</p> -</div> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_169" id="Page_169">« 169 »</a></span></p> - - -<p class="caption2"><a name="CHAPTER_VII" id="CHAPTER_VII">CHAPTER VII.</a><br /> - -OPPONENTS AND OBJECTIONS.</p> - - -<p class="p0"><span class="smcap">The</span> active objectors to the animal nature of Eozoon -have been few, though some of them have returned to -the attack with a pertinacity and determination which -would lead one to believe that they think the most -sacred interests of science to be dependent on the -annihilation of this proto-foraminifer. I do not propose -here to treat of the objections in detail. I have -presented the case of Eozoon on its own merits, and -on these it must stand. I may merely state that the -objectors strive to account for the existence of Eozoon -by purely mineral deposition, and that the complicated -changes which they require to suppose are perhaps the -strongest indirect evidence for the necessity of regarding -the structures as organic. The reader who desires -to appreciate this may consult the notes to this -chapter.<a name="FNanchor_40" id="FNanchor_40"></a><a href="#Footnote_40" class="fnanchor">[AN]</a></p> - -<div class="footnote"> - -<p><a name="Footnote_40" id="Footnote_40"></a><a href="#FNanchor_40"><span class="label">[AN]</span></a> Also Rowney and King’s papers in <i>Journal Geological -Society</i>, August, 1866; and <i>Proceedings Irish Academy</i>, 1870 -and 1871.</p> -</div> - -<p>I confess that I feel disposed to treat very tenderly -the position of objectors. The facts I have stated -make large demands on the faith of the greater part -even of naturalists. Very few geologists or naturalists -<span class="pagenum"><a name="Page_170" id="Page_170">« 170 »</a></span> -have much knowledge of the structure of foraminiferal -shells, or would be able under the microscope to -recognise them with certainty. Nor have they any -distinct ideas of the appearances of such structures -under different kinds of preservation and mineralisation. -Further, they have long been accustomed to -regard the so-called Azoic rocks as not only destitute -of organic remains, but as being in such a state of -metamorphism that these could not have been preserved -had they existed. Few, therefore, are able -intelligently to decide for themselves, and so they are -called on to trust to the investigations of others, and -on their testimony to modify in a marked degree their -previous beliefs as to the duration of life on our planet. -In these circumstances it is rather wonderful that the -researches made with reference to Eozoon have met -with so general acceptance, and that the resurrection -of this ancient inhabitant of the earth has not aroused -more of the sceptical tendency of our age.</p> - -<p>It must not be lost sight of, however, that in such -cases there may exist a large amount of undeveloped -and even unconscious scepticism, which shows itself -not in active opposition, but merely in quietly ignoring -this great discovery, or regarding it with doubt, as an -uncertain or unestablished point in science. Such -scepticism may best be met by the plain and simple -statements in the foregoing chapters, and by the illustrations -accompanying them. It may nevertheless be -profitable to review some of the points referred to, and -to present some considerations making the existence of -<span class="pagenum"><a name="Page_171" id="Page_171">« 171 »</a></span> -Laurentian life less anomalous than may at first sight -be supposed. One of these is the fact that the discovery -of Eozoon brings the rocks of the Laurentian -system into more full harmony with the other geological -formations. It explains the origin of the Laurentian -limestones in consistency with that of similar -rocks in the later periods, and in like manner it helps -us to account for the graphite and sulphides and iron -ores of these old rocks. It shows us that no time was -lost in the introduction of life on the earth. Otherwise -there would have been a vast lapse of time in which, -while the conditions suitable to life were probably present, -no living thing existed to take advantage of -these conditions. Further, it gives a more simple -beginning of life than that afforded by the more complex -fauna of the Primordial age; and this is more in -accordance with what we know of the slow and gradual -introduction of new forms of living things during the -vast periods of Palæozoic time. In connection with -this it opens a new and promising field of observation -in the older rocks, and if this should prove fertile, its -exploration may afford a vast harvest of new forms to -the geologists of the present and coming time. -This result will be in entire accordance with what -has taken place before in the history of geological discovery. -It is not very long since the old and semi-metamorphic -sediments constituting the great Silurian -and Cambrian systems were massed together in geological -classifications as primitive or primary rocks, -destitute or nearly destitute of organic remains. The -<span class="pagenum"><a name="Page_172" id="Page_172">« 172 »</a></span> -brilliant discoveries of Sedgwick, Murchison, Barrande, -and a host of others, have peopled these once barren -regions; and they now stretch before our wondering -gaze in the long vistas of early Palæozoic life. So -we now look out from the Cambrian shore upon the -vast ocean of the Huronian and Laurentian, all to us -yet tenantless, except for the few organisms, which, like -stray shells cast upon the beach, or a far-off land dimly -seen in the distance, incite to further researches, and -to the exploration of the unknown treasures that -still lie undiscovered. It would be a suitable culmination -of the geological work of the last half-century, and -one within reach at least of our immediate successors, -to fill up this great blank, and to trace back the Primordial -life to the stage of Eozoon, and perhaps even -beyond this, to predecessors which may have existed at -the beginning of the Lower Laurentian, when the -earliest sediments of that great formation were laid -down. Vast unexplored areas of Laurentian and Huronian -rocks exist in the Old World and the New. The -most ample facilities for microscopic examination of -rocks may now be obtained; and I could wish that one -result of the publication of these pages may be to -direct the attention of some of the younger and more -active geologists to these fields of investigation. It is -to be observed also that such regions are among the -richest in useful minerals, and there is no reason why -search for these fossils should not be connected with -other and more practically useful researches. On this -subject it will not be out of place to quote the remarks -<span class="pagenum"><a name="Page_173" id="Page_173">« 173 »</a></span> -which I made in one of my earlier papers on the -Laurentian fossils:—</p> - -<p>"This subject opens up several interesting fields of -chemical, physiological, and geological inquiry. One -of these relates to the conclusions stated by Dr. Hunt -as to the probable existence of a large amount of carbonic -acid in the Laurentian atmosphere, and of much -carbonate of lime in the seas of that period, and the -possible relation of this to the abundance of certain -low forms of plants and animals. Another is the comparison -already instituted by Professor Huxley and -Dr. Carpenter, between the conditions of the Laurentian -and those of the deeper parts of the modern ocean. -Another is the possible occurrence of other forms of -animal life than Eozoon and Annelids, which I have -stated in my paper of 1864, after extensive microscopic -study of the Laurentian limestones, to be indicated by -the occurrence of calcareous fragments, differing in -structure from Eozoon, but at present of unknown -nature. Another is the effort to bridge over, by -further discoveries similar to that of the <i>Eozoon Bavaricum</i> -of Gümbel, the gap now existing between the -life of the Lower Laurentian and that of the Primordial -Silurian or Cambrian period. It is scarcely too -much to say that these inquiries open up a new world -of thought and investigation, and hold out the hope of -bringing us into the presence of the actual origin of -organic life on our planet, though this may perhaps be -found to have been Prelaurentian. I would here take -the opportunity of stating that, in proposing the name -<span class="pagenum"><a name="Page_174" id="Page_174">« 174 »</a></span> -Eozoon for the first fossil of the Laurentian, and in -suggesting for the period the name “Eozoic,” I have -by no means desired to exclude the possibility of forms -of life which may have been precursors of what is now -to us the dawn of organic existence. Should remains -of still older organisms be found in those rocks now -known to us only by pebbles in the Laurentian, these -names will at least serve to mark an important stage -in geological investigation."</p> - -<p>But what if the result of such investigations should -be to produce more sceptics, or to bring to light mineral -structures so resembling Eozoon as to throw doubt -upon the whole of the results detailed in these chapters? -I can fancy that this might be the first consequence, -more especially if the investigations were in -the hands of persons more conversant with minerals -than with fossils; but I see no reason to fear the -ultimate results. In any case, no doubt, the value of -the researches hitherto made may be diminished. It -is always the fate of discoverers in Natural Science, -either to be followed by opponents who temporarily or -permanently impugn or destroy the value of their new -facts, or by other investigators who push on the knowledge -of facts and principles so far beyond their standpoint -that the original discoveries are cast into the -shade. This is a fatality incident to the progress of -scientific work, from which no man can be free; and in -so far as such matters are concerned, we must all be -content to share the fate of the old fossils whose -history we investigate, and, having served our day and -<span class="pagenum"><a name="Page_175" id="Page_175">« 175 »</a></span> -generation to give place to others. If any part of our -work should stand the fire of discussion let us be -thankful. One thing at least is certain, that such -careful surveys as those in the Laurentian rocks of -Canada which led to the discovery of Eozoon, and -such microscopic examinations as those by which it -has been worked up and presented to the public, -cannot fail to yield good results of one kind or -another. Already the attention excited by the controversies -about Eozoon, by attracting investigators -to the study of various microscopic and imitative -forms in rocks, has promoted the advancement of -knowledge, and must do so still more. For my own -part, though I am not content to base all my reputation -on such work as I have done with respect to this -old fossil, I am willing at least to take the responsibility -of the results I have announced, whatever conclusions -may be finally reached; and in the consciousness -of an honest effort to extend the knowledge of -nature, to look forward to a better fame than any -that could result from the most successful and permanent -vindication of every detail of our scientific -discoveries, even if they could be pushed to a point -which no subsequent investigation in the same difficult -line of research would be able to overpass.</p> - -<p>Contenting myself with these general remarks, I -shall, for the benefit of those who relish geological -controversy, append to this chapter a summary of the -objections urged by the most active opponents of the -animal nature of Eozoon, with the replies that may be -<span class="pagenum"><a name="Page_176" id="Page_176">« 176 »</a></span> -or have been given; and I now merely add (in <a href="#fig_49">fig. 49</a>) -a magnified camera tracing of a portion of a lamina -of Eozoon with its canals and tubuli, to show more -fully the nature of the structures in controversy.</p> - -<div class="fig_center" style="width: 383px;"> -<a name="fig_49" id="fig_49"></a> -<img src="images/fig_49.png" width="383" height="319" alt="" /> -<p class="cap_center"><span class="smcap">Fig. 49.</span> <i>Portion of a thin Transverse Slice of a Lamina of Eozoon, -magnified, showing its structure, as traced with the camera.</i></p> - -<p class="cap_center2">(<i>a.</i>) Nummuline wall of under side. (<i>b.</i>) Intermediate skeleton with canals. -(<i>a′.</i>) Nummuline wall of upper side. The two lower figures show the lower -and upper sides more highly magnified. The specimen is one in which the -canals are unusually well seen.</p> -</div> - -<p>It may be well, however, to sum up the evidence as -it has been presented by Sir W. E. Logan, Dr. Carpenter, -Dr. Hunt, and the author, in a short and intelligible -form; and I shall do so under a few brief -heads, with some explanatory remarks:—</p> - -<p>1. The Lower Laurentian of Canada, a rock formation -<span class="pagenum"><a name="Page_177" id="Page_177">« 177 »</a></span> -whose distribution, age, and structure have been -thoroughly worked out by the Canadian Survey, is -found to contain thick and widely distributed beds of -limestone, related to the other beds in the same way -in which limestones occur in the sediments of other -geological formations. There also occur in the same -formation, graphite, iron ores, and metallic sulphides, -in such relations as to suggest the idea that the limestones -as well as these other minerals are of organic -origin.</p> - -<p>2. In the limestones are found laminated bodies of -definite form and structure, composed of calcite alternating -with serpentine and other minerals. The forms -of these bodies suggested a resemblance to the Silurian -Stromatoporæ, and the different mineral substances -associated with the calcite in the production -of similar forms, showed that these were not accidental -or concretionary.</p> - -<p>3. On microscopic examination, it proved that the -calcareous laminæ of these forms were similar in structure -to the shells of modern and fossil Foraminifera, -more especially those of the Rotaline and Nummuline -types, and that the finer structures, though usually -filled with serpentine and other hydrous silicates, were -sometimes occupied with calcite, pyroxene, or dolomite, -showing that they must when recent have been empty -canals and tubes.</p> - -<p>4. The mode of filling thus suggested for the chambers -and tubes of Eozoon, is precisely that which takes -place in modern Foraminifera filled with glauconite, -<span class="pagenum"><a name="Page_178" id="Page_178">« 178 »</a></span> -and in Palæozoic crinoids and corals filled with other -hydrous silicates.</p> - -<p>5. The type of growth and structure predicated of -Eozoon from the observed appearances, in its great -size, its laminated and acervuline forms, and in its -canal system and tubulation, are not only in conformity -with those of other Foraminifera, but such as -might be expected in a very ancient form of that -group.</p> - -<p>6. Indications exist of other organic bodies in the -limestones containing Eozoon, and also of the Eozoon -being preserved not only in reefs but in drifted fragmental -beds as in the case of modern corals.</p> - -<p>7. Similar organic structures have been found in -the Laurentian limestones of Massachusetts and New -York, and also in those of various parts of Europe, -and Dr. Gümbel has found an additional species in -rocks succeeding the Laurentian in age.</p> - -<p>8. The manner in which the structures of Eozoon -are affected by the faulting, development of crystals, -mineral veins, and other effects of disturbance and -metamorphism in the containing rocks, is precisely -that which might be expected on the supposition that -it is of organic origin.</p> - -<p>9. The exertions of several active and able opponents -have failed to show how, otherwise than by -organic agency, such structures as those of Eozoon -can be formed, except on the supposition of pseudomorphism -and replacement, which must be regarded as -chemically extravagant, and which would equally impugn -<span class="pagenum"><a name="Page_179" id="Page_179">« 179 »</a></span> -the validity of all fossils determined by microscopic -structure. In like manner all comparisons of -these structures with dendritic and other imitative -forms have signally failed, in the opinion of those best -qualified to judge.</p> - -<p>Another and perhaps simpler way of putting the -case is the following:—Only three general modes of -accounting for the existence of Eozoon have been -proposed. The first is that of Professors King and -Rowney, who regard the chambers and canals filled -with serpentine as arising from the erosion or partial -dissolving away of serpentine and its replacement by -calcite. The objections to this are conclusive. It -does not explain the nummuline wall, which has to be -separately accounted for by confounding it, contrary -to the observed facts, with the veins of fibrous serpentine -which actually pass through cracks in the fossil. -Such replacement is in the highest degree unlikely on -chemical grounds, and there is no evidence of it in the -numerous serpentine grains, nodules, and bands in the -Laurentian limestones. On the other hand, the opposite -replacement, that of limestone by serpentine, -seems to have occurred. The mechanical difficulties -in accounting for the delicate canals on this theory are -also insurmountable. Finally, it does not account for -the specimens preserved in pyroxene and other silicates, -and in dolomite and calcite. A second mode of -accounting for the facts is that the Eozoon forms are -merely peculiar concretions. But this fails to account -for their great difference from the other serpentine -<span class="pagenum"><a name="Page_180" id="Page_180">« 180 »</a></span> -concretions in the same beds, and for their regularity -of plan and the delicacy of their structure, and also -for minerals of different kinds entering into their -composition, and still presenting precisely the same -forms and structures. The only remaining theory is -that of the filling of cavities by infiltration with -serpentine. This accords with the fact that such -infiltration by minerals akin to serpentine exists in -fossils in later rocks. It also accords with the known -aqueous origin of the serpentine nodules and bands, -the veins of fibrous serpentine, and the other minerals -found filling the cavities of Eozoon. Even the pyroxene -has been shown by Hunt to exist in the -Laurentian in veins of aqueous origin. The only -difficulty existing on this view is how a calcite -skeleton with such chambers, canals, and tubuli -could be formed; and this is solved by the discovery -that all these facts correspond precisely with those to -be found in the shells of modern oceanic Foraminifera. -The existence then of Eozoon, its structure, and its -relations to the containing rocks and minerals being -admitted, no rational explanation of its origin seems -at present possible other than that advocated in the -preceding pages.</p> - -<p>If the reader will now turn to <a href="#Plate_VIII">Plate. VIII.</a>, page -207, he will find some interesting illustrations of -several very important facts bearing on the above -arguments. <a href="#Plate_VIII">Fig. 1</a> represents a portion of a very -thin slice of a specimen traversed by veins of fibrous -serpentine or chrysotile, and having the calcite of -<span class="pagenum"><a name="Page_181" id="Page_181">« 181 »</a></span> -the walls more broken by cleavage planes than usual. -The portion selected shows a part of one of the -chambers filled with serpentine, which presents the -usual curdled aspect almost impossible to represent -in a drawing (<i>s</i>). It is traversed by a branching -vein of chrysotile (<i>s</i>′), which, where cut precisely -parallel to its fibres, shows clear fine cross lines, -indicating the sides of its constituent prisms, and -where the plane of section has passed obliquely to its -fibres, has a curiously stippled or frowsy appearance. -On either side of the serpentine band is the nummuline -or proper wall, showing under a low power a -milky appearance, which, with a higher power, -becomes resolved into a tissue of the most beautiful -parallel threads, representing the filling of its tubuli. -Nothing can be more distinct than the appearances -presented by this wall and the chrysotile vein, under -every variety of magnifying power and illumination; -and all who have had an opportunity of examining -my specimens have expressed astonishment that appearances -so dissimilar should have been confounded -with each other. On the lower side two indentations -are seen in the proper wall (<i>c</i>). These are connected -with the openings into small subordinate chamberlets, -one of which is in part included in the thickness of -the slice. At the upper and lower parts of the figure -are seen portions of the intermediate skeleton traversed -by canals, which in the lower part are very large, -though from the analogy of other specimens it is -probable that they have in their interstices minute -<span class="pagenum"><a name="Page_182" id="Page_182">« 182 »</a></span> -canaliculi not visible in this slice. <a href="#Plate_VIII">Fig. 2</a>, from the -same specimen, shows the termination of one of the -canals against the proper wall, its end expanding -into a wide disc of sarcode on the surface of the wall, -as may be seen in similar structures in modern -Foraminifera. In this specimen the canals are beautifully -smooth and cylindrical, but they sometimes -present a knotted or jointed appearance, especially in -specimens decalcified by acids, in which perhaps some -erosion has taken place. They are also occasionally -fringed with minute crystals, especially in those specimens -in which the calcite has been partially replaced -with other minerals. <a href="#Plate_VIII">Fig. 3</a> shows an example of -faulting of the proper wall, an appearance not infrequently -observed; and it also shows a vein -chrysotile crossing the line of fault, and not itself -affected by it—a clear evidence of its posterior origin. -<a href="#Plate_VIII">Figs. 4 and 5</a> are examples of specimens having -the canals filled with dolomite, and showing extremely -fine canals in the interstices of the others: -an appearance observed only in the thicker parts of -the skeleton, and when these are very well preserved. -These dolomitized portions require some precautions -for their observation, either in slices or decalcified -specimens, but when properly managed they show -the structures in very great perfection. The specimen -in <a href="#fig_5">fig. 5</a> is from an abnormally thick portion of -intermediate skeleton, having unusually thick canals, -and referred to in a previous chapter.</p> - -<p>One object which I have in view in thus minutely -<span class="pagenum"><a name="Page_183" id="Page_183">« 183 »</a></span> -directing attention to these illustrations, is to show -the nature of the misapprehensions which may occur -in examining specimens of this kind, and at the same -time the certainty which may be attained when proper -precautions are taken. I may add that such structures -as those referred to are best seen in extremely -thin slices, and that the observer must not -expect that every specimen will exhibit them equally -well. It is only by preparing and examining many -specimens that the best results can be obtained. It -often happens that one specimen is required to show -well one part of the structures, and a different one -to show another; and previous to actual trial, it is -not easy to say which portion of the structures any -particular fragment will show most clearly. This -renders it somewhat difficult to supply one’s friends -with specimens. Really good slices can be prepared -only from the best material and by skilled manipulators; -imperfect slices may only mislead; and rough -specimens may not be properly prepared by persons -unaccustomed to the work, or if so prepared may -not turn out satisfactory, or may not be skilfully -examined. These difficulties, however, Eozoon shares -with other specimens in micro-geology, and I have -experienced similar disappointments in the case of -fossil wood.</p> - -<p class="pmb4">In conclusion of this part of the subject, and -referring to the notes appended to this chapter for -further details, I would express the hope that those -who have hitherto opposed the interpretation of Eozoon -<span class="pagenum"><a name="Page_184" id="Page_184">« 184 »</a></span> -as organic, and to whose ability and honesty of -purpose I willingly bear testimony, will find themselves -enabled to acknowledge at least the reasonable -probability of that interpretation of these remarkable -forms and structures.</p> - - -<hr class="r20" /> - -<p class="caption3">NOTES TO CHAPTER VII.</p> - -<p class="center">(A.) <span class="smcap">Objections of Profs. King and Rowney.</span></p> - -<p class="center smaller"><i>Trans. Royal Irish Academy, July, 1869.</i><a name="FNanchor_41" id="FNanchor_41"></a><a href="#Footnote_41" class="fnanchor">[AO]</a></p> - -<div class="footnote"> -<p><a name="Footnote_41" id="Footnote_41"></a><a href="#FNanchor_41"><span class="label">[AO]</span></a> Reprinted in the <i>Annals and Magazine of Natural History</i>, May, -1874.</p> -</div> - -<div class="blockquot"> -<p>The following summary, given by these authors, may be -taken as including the substance of their objections to the -animal nature of Eozoon. I shall give them in their words -and follow them with short answers to each.</p> - -<p>"1st. The serpentine in ophitic rocks has been shown to -present appearances which can only be explained on the view -that it undergoes structural and chemical changes, causing it -to pass into variously subdivided states, and etching out the -resulting portions into a variety of forms—grains and plates, -with lobulated or segmented surfaces—fibres and aciculi—simple -and branching configurations. Crystals of malacolite, -often associated with the serpentine, manifest some of these -changes in a remarkable degree.</p> - -<p>"2nd. The ‘intermediate skeleton’ of Eozoon (which we -hold to be the calcareous matrix of the above lobulated -grains, etc.) is completely paralleled in various crystalline -rocks—notably marble containing grains of coccolite (Aker -and Tyree), pargasite (Finland), chondrodite (New Jersey, etc.)</p> - -<p>"3rd. The ‘chamber casts’ in the acervuline variety of -Eozoon are more or less paralleled by the grains of the -mineral silicates in the pre-cited marbles.</p> - -<p><span class="pagenum"><a name="Page_185" id="Page_185">« 185 »</a></span></p> - -<p>"4th. The ‘chamber casts’ being composed occasionally of -loganite and malacolite, besides serpentine, is a fact which, -instead of favouring their organic origin, as supposed, must -be held as a proof of their having been produced by mineral -agencies; inasmuch as these three silicates have a close -pseudomorphic relationship, and may therefore replace one -another in their naturally prescribed order.</p> - -<p>"5th. Dr. Gümbel, observing rounded, cylindrical, or tuberculated -grains of coccolite and pargasite in crystalline calcareous -marbles, considered them to be ‘chamber casts,’ or -of organic origin. We have shown that such grains often -present crystalline planes, angles, and edges; a fact clearly -proving that they were originally simple or compound crystals -that have undergone external decretion by chemical or solvent -action.</p> - -<p>"6th. We have adduced evidences to show that the ‘nummuline -layer’ in its typical condition—that is, consisting of -cylindrical aciculi, separated by interspaces filled with calcite—has -originated directly from closely packed fibres; these -from chrysotile or asbestiform serpentine; this from incipiently -fibrous serpentine; and the latter from the same -mineral in its amorphous or structureless condition.</p> - -<p>"7th. The ‘nummuline layer,’ in its typical condition, unmistakably -occurs in cracks or fissures, both in Canadian and -Connemara ophite.</p> - -<p>"8th. The ‘nummuline layer’ is paralleled by the fibrous -coat which is occasionally present on the surface of grains of -chondrodite.</p> - -<p>"9th. We have shown that the relative position of two superposed -asbestiform layers (an <i>upper</i> and an <i>under</i> ‘proper -wall’), and the admitted fact of their component aciculi -often passing continuously and without interruption from one -‘chamber cast’ to another, to the exclusion of the ‘intermediate -skeleton,’ are totally incompatible with the idea of -the ‘nummuline layer’ having resulted from pseudopodial -tubulation.</p> - -<p>"10th. The so-called ‘stolons’ and ‘passages of communication -exactly corresponding with those described in <i>Cycloclypeus</i>,’ -<span class="pagenum"><a name="Page_186" id="Page_186">« 186 »</a></span> -have been shown to be tabular crystals and variously -formed bodies, belonging to different minerals, wedged crossways -or obliquely in the calcareous interspaces between the -grains and plates of serpentine.</p> - -<p>"11th. The ‘canal system’ is composed of serpentine, or -malacolite. Its typical kinds in the first of these minerals -may be traced in all stages of formation out of plates, prisms, -and other solids, undergoing a process of superficial decretion. -Those in malacolite are made up of crystals—single, or aggregated -together—that have had their planes, angles, and edges -rounded off; or have become further reduced by some solvent.</p> - -<p>"12th. The ‘canal system’ in its remarkable branching -varieties is completely paralleled by crystalline configurations -in the coccolite marble of Aker, in Sweden; and in the -crevices of a crystal of spinel imbedded in a calcitic matrix -from Amity, New York.</p> - -<p>"13th. The <i>configurations</i>, presumed to represent the ‘canal -systems,’ are <i>totally without any regularity</i> of form, of relative -size, or of arrangement; and they occur independently of and -apart from other ‘eozoonal features’ (Amity, Boden, etc.); -facts not only demonstrating them to be purely mineral -products, but which strike at the root of the idea that they are -of organic origin.</p> - -<p>"14th. In answer to the argument that as all the foregoing -‘eozoonal features’ are occasionally found together in ophite, -the combination must be considered a conclusive evidence of -their organic origin, we have shown, from the composition, -physical characters, and circumstances of occurrence and -association of their component serpentine, that they represent -the structural and chemical changes which are eminently and -peculiarly characteristic of this mineral. It has also been -shown that the combination is paralleled to a remarkable -extent in chondrodite and its calcitic matrix.</p> - -<p>"15th. The ‘regular alternation of lamellæ of calcareous and -silicious minerals’ (respectively representing the ‘intermediate -skeleton’ and ‘chamber casts’) occasionally seen in -ophite, and considered to be a ‘fundamental fact’ evidencing -an organic arrangement, is proved to be a <i>mineralogical</i> -<span class="pagenum"><a name="Page_187" id="Page_187">« 187 »</a></span> -phenomenon by the fact that a similar alternation occurs in -amphiboline-calcitic marbles, and gneissose rocks.</p> - -<p>"16th. In order to account for certain <i>untoward</i> difficulties -presented by the configurations forming the ‘canal system,’ -and the aciculi of the ‘nummuline layer’—that is, when they -occur as ‘<i>solid bundles</i>’—or are ‘<i>closely packed</i>’—or ‘<i>appear -to be glued together</i>’—Dr. Carpenter has proposed the theory -that the sarcodic extensions which they are presumed to represent -have been ‘turned into stone’ (a ‘silicious mineral’) -‘by Nature’s cunning’ (‘just as the sarcodic layer on the -surface of the shell of living Foraminifers is formed by the -spreading out of <i>coalesced</i> bundles of the pseudopodia that -have emerged from the chamber wall’)—‘by a process of -chemical substitution <i>before</i> their destruction by ordinary -decomposition.’ We showed this quasi-alchymical theory to -be altogether unscientific.</p> - -<p>"17th. The ‘silicious mineral’ (serpentine) has been analogued -with those forming the variously-formed casts (in -‘glauconite,’ etc.) of recent and fossil Foraminifers. We have -shown that the mineral silicates of Eozoon have no relation -whatever to the substances composing such casts.</p> - -<p>"18th. Dr. Hunt, in order to account for the serpentine, -loganite, and malacolite, being the presumed in-filling substances -of Eozoon, has conceived the ‘novel doctrine,’ that -such minerals were <i>directly</i> deposited in the ocean waters in -which this ‘fossil’ lived. We have gone over all his evidences -and arguments without finding <i>one</i> to be substantiated.</p> - -<p>"19th. Having investigated the alleged cases of ‘chambers’ -and ‘tubes’ occurring ‘filled with calcite,’ and presumed to -be ‘a conclusive answer to’ our ‘objections,’ we have shown -that there are the strongest grounds for removing them from -the category of reliable evidences on the side of the organic -doctrine. The Tudor specimen has been shown to be equally -unavailable.</p> - -<p>"20th. The occurrence of the best preserved specimens of -Eozoon Canadense in rocks that are in a ‘<i>highly crystalline -condition</i>’ (Dawson) must be accepted as a fact utterly fatal -to its organic origin.</p> -</div> - -<p><span class="pagenum"><a name="Page_188" id="Page_188">« 188 »</a></span></p> - -<div class="blockquot"> -<p>“21st. The occurrence of ‘eozoonal features’ <i>solely</i> in crystalline -or metamorphosed rocks, belonging to the Laurentian, -the Lower Silurian, and the Liassic systems—never in ordinary -unaltered deposits of these and the intermediate systems—must -be assumed as completely demonstrating their purely -mineral origin.”</p> -</div> - -<p>The answers already given to these objections may be -summed up severally as follows:—</p> - -<div class="blockquot"> -<p>1st. This is a mere hypothesis to account for the forms presented -by serpentine grains and by Eozoon. Hunt has shown -that it is untenable chemically, and has completely exploded it -in his recent papers on Chemistry and Geology.<a name="FNanchor_42" id="FNanchor_42"></a><a href="#Footnote_42" class="fnanchor">[AP]</a> My own -observations show that it does not accord with the mode of -occurrence of serpentine in the Laurentian limestones of -Canada.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_42" id="Footnote_42"></a><a href="#FNanchor_42"><span class="label">[AP]</span></a> Boston, 1874.</p> -</div> - -<div class="blockquot"> -<p>2nd. Some of the things stated to parallel the intermediate -skeleton of Eozoon, are probably themselves examples of that -skeleton. Others have been shown to have no resemblance -to it.</p> - -<p>3rd. The words “more or less” indicate the precise value of -this statement, in a question of comparison between mineral -and organic structures. So the prismatic structure of satin-spar -may be said “more or less” to resemble that of a shell, -or of the cells of a Stenopora.</p> - -<p>4th. This overlooks the filling of chamber casts with pyroxene, -dolomite, or limestone. Even in the case of loganite -this objection is of no value unless it can be applied equally -to the similar silicates which fill cavities of fossils<a name="FNanchor_43" id="FNanchor_43"></a><a href="#Footnote_43" class="fnanchor">[AQ]</a> in the -Silurian limestones and in the green-sand.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_43" id="Footnote_43"></a><a href="#FNanchor_43"><span class="label">[AQ]</span></a> See for a full discussion of this subject Dr. Hunt’s “Papers” -above referred to.</p> -</div> - -<div class="blockquot"> -<p>5th. Dr. Gümbel’s observations are those of a highly skilled -and accurate observer. Even if crystalline forms appear in -“chamber casts,” this is as likely to be a result of the injury -of organic structures by crystallization, as of the partial effacement -of crystals by other actions. Crystalline faces occur -abundantly in many undoubted fossil woods and corals; and -crystals not unfrequently cross and interfere with the structures -in such specimens.</p> -</div> - -<p><span class="pagenum"><a name="Page_189" id="Page_189">« 189 »</a></span></p> - -<div class="blockquot"> -<p>6th. On the contrary, the Canadian specimens prove clearly -that the veins of chrysotile have been filled subsequently to -the existence of Eozoon in its present state, and that there is -no connection whatever between them and the Nummuline -wall.</p> - -<p>7th. This I have never seen in all my examinations of -Eozoon. The writers must have mistaken veins of fibrous serpentine -for the nummuline wall.</p> - -<p>8th. Only if such grains of chondrodite are themselves -casts of foraminiferal chambers. But Messrs. King and -Rowney have repeatedly figured mere groups of crystals as -examples of the nummuline wall.</p> - -<p>9th. Dr. Carpenter has shown that this objection depends -on a misconception of the structure of modern Foraminifera, -which show similar appearances.</p> - -<p>10th. That disseminated crystals occur in the Eozoon limestones -is a familiar fact, and one paralleled in many other -more or less altered organic limestones. Foreign bodies also -occur in the chambers filled with loganite and other minerals; -but these need not any more be confounded with the pillars -and walls connecting the laminæ than the sand filling a dead -coral with its lamellæ. Further, it is well known that foreign -bodies are often contained both in the testa and chambers even -of recent Foraminifera.</p> - -<p>11th. The canal system is not always filled with serpentine -or malacolite; and when filled with pyroxene, dolomite, or -calcite, the forms are the same. The irregularities spoken of -are perhaps more manifest in the serpentine specimens, -because this mineral has in places encroached on or partially -replaced the calcite walls.</p> - -<p>12th. If this is true of the Aker marble, then it must contain -Eozoon; and specimens of the Amity limestone which -I have examined, certainly contain large fragments of Eozoon.</p> - -<p>13th. The configuration of the canal system is quite -definite, though varying in coarseness and fineness. It is -not known to occur independently of the forms of Eozoon -except in fragmental deposits.</p> -</div> - -<p><span class="pagenum"><a name="Page_190" id="Page_190">« 190 »</a></span></p> - -<div class="blockquot"> -<p>14th. The argument is not that they are “occasionally found -together in ophite,” but that they are found together in specimens -preserved by different minerals, and in such a way as to -show that all these minerals have filled chambers, canals, and -tubuli, previously existing in a skeleton of limestone.</p> - -<p>15th. The lamination of Eozoon is not like that of any rock, -but a strictly limited and definite form, comparable with that -of Stromatopora.</p> - -<p>16th. This I pass over, as a mere captious criticism of modes -of expression used by Dr. Carpenter.</p> - -<p>17th. Dr. Hunt, whose knowledge of chemical geology -should give the greatest weight to his judgment, maintains -the deposition of serpentine and loganite to have taken place -in a manner similar to that of jollyte and glauconite in undoubted -fossils: and this would seem to be a clear deduction -from the facts he has stated, and from the chemical character -of the substances. My own observations of the mode of occurrence -of serpentine in the Eozoon limestones lead me to -the same result.</p> - -<p>18th. Dr. Hunt’s arguments on the subject, as recently -presented in his <i>Papers on Chemistry and Geology</i>, need -only be studied by any candid and competent chemist or -mineralogist to lead to a very different conclusion from that of -the objectors.</p> - -<p>19th. This is a mere statement of opinion. The fact remains -that the chambers and canals are sometimes filled with -calcite.</p> - -<p>20th. That the occurrence of Eozoon in crystalline limestones -is “utterly fatal” to its claims to organic origin can be -held only by those who are utterly ignorant of the frequency -with which organic remains are preserved in highly crystalline -limestones of all ages. In addition to other examples -mentioned above, I may state that the curious specimen of -Cœnostroma from the Guelph limestone figured in <a href="#CHAPTER_VI">Chapter VI.</a>, -has been converted into a perfectly crystalline dolomite, while -its canals and cavities have been filled with calcite, since -weathered out.</p> -</div> - -<p><span class="pagenum"><a name="Page_191" id="Page_191">« 191 »</a></span></p> - -<div class="blockquot"> -<p>21st. This limited occurrence is an assumption contrary to -facts. It leaves out of account the Tudor specimens, and also -the abundant occurrence of the Stromatoporoid successors of -Eozoon in the Silurian and Devonian. Further, even if the -Eozoon were limited to the Laurentian, this would not be -remarkable; and since all the Laurentian rocks known to us -are more or less altered, it could not in that case occur in -unaltered rocks.</p> - -<p>I have gone over these objections seriatim, because, though -individually weak, they have an imposing appearance in -the aggregate, and have been paraded as a conclusive settlement -of the questions at issue. They have even been reprinted -in the year just past in an English journal of some -standing, which professes to accept only original contributions -to science, but has deviated from its rule in their favour. I -may be excused for adding a portion of my original argument -in opposition to these objections, as given more at length in -the <i>Transactions of the Irish Academy</i>.</p> - -<p>1. I object to the authors‘ mode of stating the question at -issue, whereby they convey to the reader the impression that -this is merely to account for the occurrence of certain peculiar -forms in ophite.</p> - -<p>With reference to this, it is to be observed that the attention -of Sir William Logan, and of the writer, was first called to -Eozoon by the occurrence in Laurentian rocks of definite -forms resembling the Silurian <i>Stromatoporæ</i>, and dissimilar -from any concretions or crystalline structures found in these -rocks. With his usual sagacity, Sir William added to these -facts the consideration that the mineral substances occurring -is these forms were so dissimilar as to suggest that the forms -themselves must be due to some extraneous cause rather than -to any crystalline or segregative tendency of their constituent -minerals. These specimens, which were exhibited by Sir -William as probably fossils, at the meeting of the American -Association in 1859, and noticed with figures in the Report of -the Canadian Survey for 1863, showed under the microscope -no minute structures. The writer, who had at the time an -opportunity of examining them, stated his belief that if fossils, -they would prove to be not Corals but Protozoa.</p> -</div> - -<p><span class="pagenum"><a name="Page_192" id="Page_192">« 192 »</a></span></p> - -<div class="blockquot"> -<p>In 1864, additional specimens having been obtained by the -Survey, slices were submitted to the writer, in which he at -once detected a well-marked canal-system, and stated, decidedly, -his belief that the forms were organic and foraminiferal. -The announcement of this discovery was first made -by Sir W. E. Logan, in <i>Silliman’s Journal</i> for 1864. So far, -the facts obtained and stated related to definite forms mineralised -by loganite, serpentine, pyroxene, dolomite, and calcite. -But before publishing these facts in detail, extensive series of -sections of all the Laurentian limestones, and of those of the -altered Quebec group of the Green Mountain range, were made, -under the direction of Sir W. E. Logan and Dr. Hunt, and -examined microscopically. Specimens were also decalcified by -acids, and subjected to chemical examination by Dr. Sterry -Hunt. The result was the conviction that the definite laminated -forms must be organic, and further, that there exist in -the Laurentian limestones fragments of such forms retaining -their structure, and also other fragments, probably organic, -but distinct from Eozoon. These conclusions were submitted -to the Geological Society of London, in 1864, after the specimens -on which they were based had been shown to Dr. Carpenter -and Professor T. R. Jones, the former of whom detected -in some of the specimens an additional foraminiferal structure—that -of the tubulation of the proper wall, which I had not -been able to make out. Subsequently, in rocks at Tudor, of -somewhat later age than those of the Lower Laurentian at -Grenville, similar structures were found in limestones not more -metamorphic than many of those which retain fossils in the -Silurian system. I make this historical statement in order to -place the question in its true light, and to show that it relates -to the organic origin of certain definite mineral masses, exhibiting, -not only the external forms of fossils, but also their -internal structure.</p> -</div> - -<p><span class="pagenum"><a name="Page_193" id="Page_193">« 193 »</a></span></p> - -<div class="blockquot"> -<p>In opposition to these facts, and to the careful deductions -drawn from them, the authors of the paper under consideration -maintain that the structures are mineral and crystalline. -I believe that in the present state of science such an attempt -to return to the doctrine of “plastic-force” as a mode of -accounting for fossils would not be tolerated for a moment, -were it not for the great antiquity and highly crystalline condition -of the rocks in which the structures are found, which -naturally create a prejudice against the idea of their being -fossiliferous. That the authors themselves feel this is apparent -from the slight manner in which they state the leading facts -above given, and from their evident anxiety to restrict the -question to the mode of occurrence of serpentine in limestone, -and to ignore the specimens of Eozoon preserved under -different mineral conditions.</p> - -<p>2. With reference to the general form of Eozoon and its -structure on the large scale, I would call attention to two -admissions of the authors of the paper, which appear to me to -be fatal to their case:—First, they admit, at page 533 [<i>Proceedings</i>, -vol. x.], their “inability to explain satisfactorily” -the alternating layers of carbonate of lime and other minerals -in the typical specimens of Canadian Eozoon. They make a -feeble attempt to establish an analogy between this and -certain concentric concretionary layers; but the cases are -clearly not parallel, and the laminæ of the Canadian Eozoon -present connecting plates and columns not explicable on any -concretionary hypothesis. If, however, they are unable to -explain the lamellar structure alone, as it appeared to Logan -in 1859, is it not rash to attempt to explain it away now, when -certain minute internal structures, corresponding to what -might have been expected on the hypothesis of its organic -origin, are added to it? If I affirm that a certain mass is the -trunk of a fossil tree, and another asserts that it is a concretion, -but professes to be unable to account for its form and its rings -of growth, surely his case becomes very weak after I have -made a slice of it, and have shown that it retains the structure -of wood.</p> - -<p>Next, they appear to admit that if specimens occur wholly -composed of carbonate of lime, their theory will fall to the -ground. Now such specimens do exist. They treat the Tudor -specimen with scepticism as probably “strings of segregated -calcite.” Since the account of that specimen was published, -additional fragments have been collected, so that new slices -have been prepared. I have examined these with care, and -am prepared to affirm that the chambers in these specimens -are filled with a dark-coloured limestone not more crystalline -than is usual in the Silurian rocks, and that the chamber -walls are composed of carbonate of lime, with the canals filled -with the same material, except where the limestone filling the -chambers has penetrated into parts of the larger ones. I -should add that the stratigraphical researches of Mr. Vennor, -of the Canadian Survey, have rendered it probable that the -beds containing these fossils, though unconformably underlying -the Lower Silurian, overlie the Lower Laurentian of the -locality, and are, therefore, probably Upper Laurentian, or -perhaps Huronian, so that the Tudor specimens may approach -in age to Gümbel’s Eozoon Bavaricum.<a name="FNanchor_44" id="FNanchor_44"></a><a href="#Footnote_44" class="fnanchor">[AR]</a></p> -</div> - -<div class="footnote"> -<p><a name="Footnote_44" id="Footnote_44"></a><a href="#FNanchor_44"><span class="label">[AR]</span></a> I may now refer in addition to the canals filled with calcite and -dolomite, detected by Dr. Carpenter and myself in specimens from -Petite Nation, and mentioned in a previous chapter. See also -<a href="#Plate_VIII">Plate VIII</a>.</p> -</div> - -<p><span class="pagenum"><a name="Page_195" id="Page_195">« 195 »</a></span></p> - -<div class="blockquot"> -<p>Further, the authors of the paper have no right to object to -our regarding the laminated specimen as “typical” Eozoon. -If the question were as to <i>typical ophite</i> the case would be -different; but the question actually is as to certain well-defined -forms which we regard as fossils, and allege to have organic -structure on the small scale, as well as lamination on the large -scale. We profess to account for the acervuline forms by the -irregular growth at the surface of the organisms, and by the -breaking of them into fragments confusedly intermingled in -great thicknesses of limestone, just as fragments of corals -occur in Palæozoic limestones; but we are under no obligation -to accept irregular or disintegrated specimens as typical; and -when objectors reason from these fragments, we have a right -to point to the more perfect examples. It would be easy to -explain the loose cells of <i>Tetradium</i> which characterize the -bird’s-eye limestone of the Lower Silurian of America, as -crystalline structures; but a comparison with the unbroken -masses of the same coral, shows their true nature. I have for -some time made the minute structure of Palæozoic limestones -a special study, and have described some of them from the -Silurian formations of Canada.<a name="FNanchor_45" id="FNanchor_45"></a><a href="#Footnote_45" class="fnanchor">[AS]</a> I possess now many additional -examples, showing fragments of various kinds of -fossils preserved in these limestones, and recognisable only by -the infiltration of their pores with different silicious minerals. -It can also be shown that in many cases the crystallization -of the carbonate of lime, both of the fossils themselves and -of their matrix, has not interfered with the perfection of the -most minute of these structures.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_45" id="Footnote_45"></a><a href="#FNanchor_45"><span class="label">[AS]</span></a> In the <i>Canadian Naturalist</i>.</p> -</div> - -<div class="blockquot"> -<p>The fact that the chambers are usually filled with silicates is -strangely regarded by the authors as an argument against the -organic nature of Eozoon. One would think that the extreme -frequency of silicious fillings of the cavities of fossils, and -even of silicious replacement of their tissues, should have -prevented the use of such an argument, without taking into -account the opposite conclusions to be drawn from the various -kinds of silicates found in the specimens, and from the modern -filling of Foraminifera by hydrous silicates, as shown by -Ehrenberg, Mantell, Carpenter, Bailey, and Pourtales.<a name="FNanchor_46" id="FNanchor_46"></a><a href="#Footnote_46" class="fnanchor">[AT]</a> -Further, I have elsewhere shown that the loganite is proved -by its texture to have been a fragmental substance, or at least -filled with loose <i>debris</i>; that the Tudor specimens have the -cavities filled with a sedimentary limestone, and that several -fragmental specimens from Madoc are actually wholly calcareous. -It is to be observed, however, that the wholly -calcareous specimens present great difficulties to an observer; -and I have no doubt that they are usually overlooked by collectors -in consequence of their not being developed by weathering, -or showing any obvious structure in fresh fractures.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_46" id="Footnote_46"></a><a href="#FNanchor_46"><span class="label">[AT]</span></a> <i>Quarterly Journal Geol. Society</i>, 1864.</p> -</div> - -<p><span class="pagenum"><a name="Page_196" id="Page_196">« 196 »</a></span></p> - -<div class="blockquot"> -<p>3. With regard to the canal system, the authors persist in -confusing the casts of it which occur in serpentine with -“metaxite” concretions, and in likening them to dendritic -crystallizations of silver, etc., and coralloidal forms of carbonate -of lime. In answer to this, I think it quite sufficient to say -that I fail to perceive the resemblance as other than very -imperfectly imitative. I may add, that the case is one of the -occurrence of a canal structure in forms which on other -grounds appear to be organic, while the concretionary forms -referred to are produced under diverse conditions, none of them -similar to those of which evidence appears in the specimens of -Eozoon. With the singular theory of pseudomorphism, by -means of which the authors now supplement their previous -objections, I leave Dr. Hunt to deal.</p> - -<p>4. With respect to the proper wall and its minute tubulation, -the essential error of the authors consists in confounding it -with fibrous and acicular crystals, and in maintaining that -because the tubuli are sometimes apparently confused and confluent -they must be inorganic. With regard to the first of these -positions, I may repeat what I have stated in former papers—that -the true cell-wall presents minute cylindrical processes -traversing carbonate of lime, and usually nearly parallel to -each other, and often slightly bulbose at the extremity. -Fibrous serpentine, on the other hand, appears as angular -crystals, closely packed together, while the numerous spicular -crystals of silicious minerals which often appear in metamorphic -limestones, and may be developed by decalcification, appear -as sharp angular needles usually radiating from centres or -irregularly disposed. Their own plate (Ophite from Skye, -King and Rowney’s Paper, <i>Proc. R. I. A.</i>, vol. x.), is an -eminent example of this; and whatever the nature of the -crystals represented, they have no appearance of being true -tubuli of Eozoon. I have very often shown microscopists and -geologists the cell-wall along with veins of chrysotile and -coatings of acicular crystals occurring in the same or similar -limestones, and they have never failed at once to recognise the -difference, especially under high powers.</p> - -<p>I do not deny that the tubulation is often imperfectly preserved, -and that in such cases the casts of the tubuli may -appear to be glued together by concretions of mineral matter, -or to be broken or imperfect. But this occurs in all fossils, -and is familiar to any microscopist examining them. How -difficult is it in many cases to detect the minute structure of -Nummulites and other fossil Foraminifera? How often does -a specimen of fossil wood present in one part distorted and -confused fibres or mere crystals, with the remains of the wood -forming phragmata between them, when in other parts it may -show the most minute structures in perfect preservation? -But who would use the disintegrated portions to invalidate -the evidence of the parts better preserved? Yet this is -precisely the argument of Professors King and Rowney, and -which they have not hesitated in using in the case of a fossil -so old as Eozoon, and so often compressed, crushed, and partly -destroyed by mineralization.</p> -</div> - -<p><span class="pagenum"><a name="Page_197" id="Page_197">« 197 »</a></span></p> - -<div class="blockquot"> -<p>I have in the above remarks confined myself to what I -regard as absolutely essential by way of explanation and -defence of the organic nature of Eozoon. It would be unprofitable -to enter into the multitude of subordinate points -raised by the authors, and their theory of mineral pseudomorphism -is discussed by my friend Dr. Hunt; but I must -say here that this theory ought, in my opinion, to afford to -any chemist a strong presumption against the validity of their -objections, especially since it confessedly does not account for -all the facts, while requiring a most complicated series of -unproved and improbable suppositions.</p> - -<p>The only other new features in the communication to which -this note refers are contained in the “supplementary note.” -The first of these relates to the grains of coccolite in the limestone -of Aker, in Sweden. Whether or not these are organic, -they are apparently different from <i>Eozoon Canadense</i>. They, -no doubt, resemble the grains referred to by Gümbel as -possibly organic, and also similar granular objects with projections -which, in a previous paper, I have described from -Laurentian limestones in Canada. These objects are of -doubtful nature; but if organic, they are distinct from -Eozoon. The second relates to the supposed crystals of -malacolite from the same place. Admitting the interpretation -given of these to be correct, they are no more related to -Eozoon than are the curious vermicular crystals of a micaceous -mineral which I have noticed in the Canadian limestones.</p> -</div> - -<p><span class="pagenum"><a name="Page_198" id="Page_198">« 198 »</a></span></p> - -<div class="blockquot"> -<p>The third and still more remarkable case is that of a spinel -from Amity, New York, containing calcite in its crevices, -including a perfect canal system preserved in malacolite. -With reference to this, as spinels of large size occur in veins -in the Laurentian rocks, I am not prepared to say that it is -absolutely impossible that fragments of limestone containing -Eozoon may not be occasionally associated with them in their -matrix. I confess, however, that until I can examine such -specimens, which I have not yet met with, I cannot, after my -experience of the tendencies of Messrs. Rowney and King to -confound other forms with those of Eozoon, accept their -determinations in a matter so critical and in a case so -unlikely.<a name="FNanchor_47" id="FNanchor_47"></a><a href="#Footnote_47" class="fnanchor">[AU]</a></p> -</div> - -<div class="footnote"> -<p><a name="Footnote_47" id="Footnote_47"></a><a href="#FNanchor_47"><span class="label">[AU]</span></a> I have since ascertained that Laurentian limestone found at -Amity, New York, and containing spinels, does hold fragments of the -intermediate skeleton of Eozoon. The limestone may have been -originally a mass of fragments of this kind with the aluminous and -magnesian material of the spinel in their interstices.</p> -</div> - -<p><span class="pagenum"><a name="Page_199" id="Page_199">« 199 »</a></span></p> - -<div class="blockquot"> - -<p>If all specimens of Eozoon were of the acervuline character, -the comparison of the chamber-casts with concretionary -granules might have some plausibility. But it is to be observed -that the laminated arrangement is the typical one; and -the study of the larger specimens, cut under the direction of -Sir W. E. Logan, shows that these laminated forms must have -grown on certain strata-planes before the deposition of the -overlying beds, and that the beds are, in part, composed of the -broken fragments of similar laminated structures. Further, -much of the apparently acervuline Eozoon rock is composed of -such broken fragments, the interstices between which should -not be confounded with the chambers: while the fact that the -serpentine fills such interstices as well as the chambers shows -that its arrangement is not concretionary. Again, these -chambers are filled in different specimens with serpentine, -pyroxene, loganite, calcareous spar, chondrodite, or even with -arenaceous limestone. It is also to be observed that the examination -of a number of limestones, other than Canadian, by -Messrs. King and Rowney, has obliged them to admit that the -laminated forms in combination with the canal-system are -“essentially Canadian,” and that the only instances of structures -clearly resembling the Canadian specimens are afforded -by limestones Laurentian in age, and in some of which (as, for -instance, in those of Bavaria and Scandinavia) Carpenter and -Gümbel have actually found the structure of Eozoon. The -other serpentine-limestones examined (for example, that of -Skye) are admitted to fail in essential points of structure; and -the only serpentine believed to be of eruptive origin examined -by them is confessedly destitute of all semblance of Eozoon. -Similar results have been attained by the more careful researches -of Prof. Gümbel, whose paper is well deserving of -study by all who have any doubts on this subject.</p> -</div> - -<p><span class="pagenum"><a name="Page_200" id="Page_200">« 200 »</a></span></p> - -<p class="caption3">(B.) <span class="smcap">Reply by Dr. Hunt to Chemical Objections</span>—(<i>Ibid.</i>).</p> - -<div class="blockquot"> - -<p>"In the <i>Proceedings of the Royal Irish Academy</i>, for July -12, 1869, Messrs. King and Rowney have given us at length -their latest corrected views on various questions connected -with Eozoon Canadense. Leaving to my friend, Dr. Dawson, -the discussion of the zoological aspects of the question, I cannot -forbear making a few criticisms on the chemical and mineralogical -views of the authors. The problem which they had -before them was to explain the occurrence of certain forms -which, to skilled observers, like Carpenter, Dawson, and -Rupert Jones, appear to possess all the structural character of -the calcareous skeleton of a foraminiferal organism, and moreover -to show how it happens that these forms of crystalline -carbonate of lime are associated with serpentine in such a way -as to lead these observers to conclude that this hydrous silicate -of magnesia filled and enveloped the calcareous skeleton, replacing -the perishable sarcode. The hypothesis now put forward -by Messrs. King and Rowney to explain the appearances -in question, is, that all this curiously arranged serpentine, -which appears to be a cast of the interior of a complex foraminiferal -organism, has been shaped or sculptured out of plates, -prisms, and other solids of serpentine, by “the erosion and -incomplete waste of the latter, <i>the definite shapes</i> being residual -portions of the solid that have not completely disappeared.” -The calcite which limits these definite shapes, or, in other -words, what is regarded as the calcareous skeleton of Eozoon, -is a ‘replacement pseudomorph’ of calcite taking the place of -the wasted and eroded serpentine. It was not a calcareous -fossil, filled and surrounded by the serpentine, but was formed -in the midst of the serpentine itself, by a mysterious agency -which dissolved away this mineral to form a mould, in which -the calcite was cast. This marvellous process can only be -paralleled by the operations of that plastic force in virtue of -which sea-shells were supposed by some old naturalists to be -generated in the midst of rocky strata. Such equivocally -formed fossils, whether oysters or Foraminifers, may well be -termed <i>pseudomorphs</i>, but we are at a loss to see with what -propriety the authors of this singular hypothesis invoke the -doctrines of mineral pseudomorphism, as taught by Rose, -Blum, Bischof, and Dana. In replacement pseudomorphs, as -understood by these authors, a mineral species disappears and -is replaced by another which retains the external form of the -first. Could it be shown that the calcite of the cell-wall of -Eozoon was once serpentine, this portion of carbonate of lime -would be a replacement pseudomorph after serpentine; but -why the portions of this mineral, which on the hypothesis of -Messrs. King and Rowney have been thus replaced, should -assume the forms of a foraminiferal skeleton, is precisely what -our authors fail to show, and, as all must see, is the gist of the -whole matter.</p> - -<p>"Messrs. King and Rowney, it will be observed, assume the -existence of calcite as a replacement pseudomorph after serpentine, -but give no evidence of the possibility of such pseudomorphs. -Both Rose and Bischof regard serpentine itself as -in all cases, of pseudomorphous origin, and as the last result -of the changes of a number of mineral species, but give us no -example of the pseudomorphous alteration of serpentine -itself. It is, according to Bischof, the very insolubility and -unalterability of serpentine which cause it to appear as the -final result of the change of so many mineral species. Delesse, -moreover, in his carefully prepared table of pseudomorphous -minerals, in which he has resumed the results of his own and -all preceding observers, does not admit the pseudomorphic replacement -of serpentine by calcite, nor indeed by any other -species.<a name="FNanchor_48" id="FNanchor_48"></a><a href="#Footnote_48" class="fnanchor">[AV]</a> If, then, such pseudomorphs exist, it appears to be -a fact hitherto unobserved, and our authors should at least -have given us some evidence of this remarkable case of pseudomorphism -by which they seek to support their singular -hypothesis.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_48" id="Footnote_48"></a><a href="#FNanchor_48"><span class="label">[AV]</span></a> <i>Annales des Mines</i>, 5, xvi., 317.</p> -</div> - -<p><span class="pagenum"><a name="Page_201" id="Page_201">« 201 »</a></span></p> - -<div class="blockquot"> - -<p>"I hasten to say, however, that I reject with Scheerer, Delesse -and Naumann, a great part of the supposed cases of mineral -pseudomorphism, and do not even admit the pseudomorphous -origin of serpentine itself, but believe that this, with many -other related silicates, has been formed by direct chemical precipitation. -This view, which our authors do me the honour to -criticise, was set forth by me in 1860 and 1861,<a name="FNanchor_49" id="FNanchor_49"></a><a href="#Footnote_49" class="fnanchor">[AW]</a> and will be -found noticed more in detail in the <i>Geological Report of -Canada</i>, for 1866, p. 229. I have there and elsewhere maintained -that ‘steatite, serpentine, pyroxene, hornblende, and in -many cases garnet, epidote, and other silicated minerals, are -formed by a crystallization and molecular re-arrangement of -silicates, generated by chemical processes in waters at the -earth’s surface.’<a name="FNanchor_50" id="FNanchor_50"></a><a href="#Footnote_50" class="fnanchor">[AX]</a></p> -</div> - -<div class="footnote"> -<p><a name="Footnote_49" id="Footnote_49"></a><a href="#FNanchor_49"><span class="label">[AW]</span></a> <i>Amer. Journ. Science</i> (2), xxix., 284; xxxii., 286.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_50" id="Footnote_50"></a><a href="#FNanchor_50"><span class="label">[AX]</span></a> <i>Ibid.</i>, xxxvii., 266; xxxviii., 183.</p> -</div> - -<p><span class="pagenum"><a name="Page_202" id="Page_202">« 202 »</a></span></p> - -<div class="blockquot"> - -<p>"This view, which at once explains the origin of all these -bedded rocks, and the fact that their constituent mineral -species, like silica and carbonate of lime, replace the perishable -matter of organic forms, is designated by Messrs. King and -Rowney ‘as so completely destitute of the characters of a -scientific hypothesis as to be wholly unworthy of consideration,’ -and they speak of my attempt to maintain this hypothesis as -‘a total collapse.’ How far this statement is from the truth -my readers shall judge. My views as to the origin of serpentine -and other silicated minerals were set forth by me as above -in 1860-1864, before anything was known of the mineralogy of -Eozoon, and were forced upon me by my studies of the older -crystalline schists of North America. Naumann had already -pointed out the necessity of some such hypothesis when he -protested against the extravagances of the pseudomorphist -school, and maintained that the beds of various silicates found -in the crystalline schists are original deposits, and not formed -by an epigenic process (<i>Geognosie</i>, ii., 65, 154, and <i>Bull. -Soc. Geol. de France</i>, 2, xviii., 678). This conclusion of -Naumann’s I have attempted to explain and support by -numerous facts and observations, which have led me to the -hypothesis in question. Gümbel, who accepts Naumann’s -view, sustains my hypothesis of the origin of these rocks in a -most emphatic manner,<a name="FNanchor_51" id="FNanchor_51"></a><a href="#Footnote_51" class="fnanchor">[AY]</a> and Credner, in discussing the genesis -of the Eozoic rocks, has most ably defended it.<a name="FNanchor_52" id="FNanchor_52"></a><a href="#Footnote_52" class="fnanchor">[AZ]</a> So much -for my theoretical views so contemptuously denounced by -Messrs. King and Rowney, which are nevertheless unhesitatingly -adopted by the two geologists of the time who have -made the most special studies of the rocks in question,—Gümbel -in Germany, and Credner in North America.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_51" id="Footnote_51"></a><a href="#FNanchor_51"><span class="label">[AY]</span></a> <i>Proc. Royal Bavarian Acad.</i> for 1866, translated in <i>Can. -Naturalist</i>, iii., 81.</p> -</div> - -<div class="footnote"> -<p><a name="Footnote_52" id="Footnote_52"></a><a href="#FNanchor_52"><span class="label">[AZ]</span></a> <i>Die Gliederung der Eozoischen Formations gruppe Nord.-Amerikas,—a -Thesis defended before the University of Leipzig, -March 15, 1869</i>, by Dr. Hermann Credner. Halle, 1869, p. 53.</p> -</div> - -<p><span class="pagenum"><a name="Page_203" id="Page_203">« 203 »</a></span></p> - -<div class="blockquot"> - -<p>“It would be a thankless task to follow Messrs. King and -Rowney through their long paper, which abounds in statements -as unsound as those I have just exposed, but I cannot -conclude without calling attention to one misconception of -theirs as to my view of the origin of limestones. They quote -Professor Hull’s remark to the effect that the researches of -the Canadian geologists and others have shown that the oldest -known limestones of the world owe their origin to Eozoon, and -remark that the existence of great limestone beds in the Eozoic -rocks seems to have influenced Lyell, Ramsay, and others in -admitting the received view of Eozoon. Were there no other -conceivable source of limestones than Eozoon or similar calcareous -skeletons, one might suppose that the presence of such -rocks in the Laurentian system could have thus influenced -these distinguished geologists, but there are found beneath the -Eozoon horizon two great formations of limestone in which -this fossil has never been detected. When found, indeed, it -owes its conservation in a readily recognisable form to the -fact, that it was preserved by the introduction of serpentine at -the time of its growth. Above the unbroken Eozoon reefs are -limestones made up apparently of the debris of Eozoon thus -preserved by serpentine, and there is no doubt that this calcareous -rhizopod, growing in water where serpentine was not -in process of formation, might, and probably did, build up pure -limestone beds like those formed in later times from the ruins -of corals and crinoids. Nor is there anything inconsistent in -this with the assertion which Messrs. King and Rowney quote -from me, viz., that the popular notion that <i>all limestone formations</i> -owe their origin to organic life is based upon a fallacy. -The idea that marine organisms originate the carbonate of -lime of their skeletons, in a manner somewhat similar to that -in which plants generate the organic matter of theirs, appears -to be commonly held among certain geologists. It cannot, -however, be too often repeated that animals only appropriate -the carbonate of lime which is furnished them by chemical -reaction. Were there no animals present to make use of it, -the carbonate of lime would accumulate in natural waters till -these became saturated, and would then be deposited in an insoluble -form; and although thousands of feet of limestone have -been formed from the calcareous skeletons of marine animals, -it is not less true that great beds of ancient marble, like many -modern travertines and tufas, have been deposited without -the intervention of life, and even in waters from which living -organisms were probably absent. To illustrate this with the -parallel case of silicious deposits, there are great beds made -up of silicious shields of diatoms. These during their lifetime -extracted from the waters the dissolved silica, which, but for -their intervention, might have accumulated till it was at length -deposited in the form of schist or of crystalline quartz. In either -case the function of the coral, the rhizopod, or the diatom is -limited to assimilating the carbonate of lime or the silica from -its solution, and the organised form thus given to these substances -is purely accidental. It is characteristic of our -authors, that, rather than admit the limestone beds of the -Eozoon rocks to have been formed like beds of coralline limestone, -or deposited as chemical precipitates like travertine, -they prefer, as they assure us, to regard them as the results of -that hitherto unheard-of process, the pseudomorphism of serpentine; -as if the deposition of the carbonate of lime in the -place of dissolved serpentine were a simpler process than its -direct deposition in one or the other of the ways which all the -world understands!”</p> -</div> - -<p><span class="pagenum"><a name="Page_204" id="Page_204">« 204 »</a></span></p> - -<p class="caption3">(C.) <span class="smcap">Dr. Carpenter on the Foraminiferal Relations of -Eozoon.</span></p> - -<div class="blockquot"> - -<p>In the <i>Annals of Natural History</i>, for June, 1874, Dr. Carpenter -has given a crushing reply to some objections raised in -that journal by Mr. Carter. He first shows, contrary to the -statement of Mr. Carter, that the fine nummuline tubulation -corresponds precisely in its direction with reference to the -chambers, with that observed in Nummulites and Orbitoides. -In the second place, he shows by clear descriptions and figures, -that the relation of the canal system to the fine tubulation is -precisely that which he had demonstrated in more recent nummuline -and rotaline Foraminifera. In the third place he adduces -additional facts to show that in some specimens of -Eozoon the calcareous skeleton has been filled with calcite -before the introduction of any foreign mineral matter. He -concludes the argument in the following words:—</p> - -<p>"I have thus shown:—(1) that the ‘utter incompatibility’ -asserted by my opponents to exist between the arrangement of -the supposed ‘nummuline tubulation’ of Eozoon and true -Nummuline structure, so far from having any real existence, -really furnishes an additional point of conformity; and (2) -that three most striking and complete points of conformity -exist between the structure of the best-preserved specimens of -Eozoon, and that of the Nummulites whose tubulation I described -in 1849, and of the Calcarina whose tubulation and -canal system I described in 1860.</p> -</div> - -<p><span class="pagenum"><a name="Page_205" id="Page_205">« 205 »</a></span></p> - -<div class="blockquot"> - -<p>"That I have not troubled myself to reply to the reiterated -arguments in favour of the doctrine [of mineral origin] advanced -by Professors King and Rowney on the strength of the -occurrence of undoubted results of mineralization in the Canadian -Ophite, and of still more marked evidences of the same -action in other Ophites, has been simply because these arguments -appeared to me, as I thought they must also appear to -others, entirely destitute of logical force. Every scientific -palæontologist I have ever been acquainted with has taken the -<i>best</i> preserved specimens, not the <i>worst</i>, as the basis of his -reconstructions; and if he should meet with distinct evidence -of characteristic organic structure in even a very small fragment -of a doubtful form, he would consider the organic origin -of that form to be thereby substantiated, whatever might be -the evidence of purely mineral arrangement which the greater -part of his specimen may present,—since he would regard -that arrangement as a probable result of <i>subsequent</i> mineralization, -by which the original organic structure has been more -or less obscured. If this is <i>not</i> to be our rule of interpretation, -a large part of the palæontological work of our time must -be thrown aside as worthless. If, for example, Professors -King and Rowney were to begin their study of Nummulites by -the examination of their most mineralized forms, they would -deem themselves justified (according to their canons of interpretation) -in denying the existence of the tubulation and -canalization which I described (in 1849) in the N. lævigata preserved -almost unaltered in the London Clay of Bracklesham -Bay.</p> - -<p>"My own notions of Eozoic structure have been formed on the -examination of the Canadian specimens selected by the experienced -discrimination of Sir William Logan, as those in which -there was <i>least</i> appearance of metamorphism; and having -found in these what I regarded as unmistakable evidence of an -organic structure conformable to the foraminiferal type, I -cannot regard it as any disproof of that conformity, either to -show that the true Eozoic structure has been frequently -altered by mineral metamorphism, or to adduce the occurrence -of Ophites more or less resembling the Eozoon of the Canadian -Laurentians at various subsequent geological epochs. The -existence of any number or variety of <i>purely mineral</i> Ophites -would not disprove the organic origin of the Canadian Eozoon—unless -it could be shown that some wonderful process of -mineralization is competent to construct not only its multiplied -alternating lamellæ of calcite and serpentine, the dendritic -extensions of the latter into the former, and the ‘acicular -layer’ of decalcified specimens, but (1) the <i>pre-existing canalization</i> -of the calcareous lamellæ, (2) the <i>unfilled nummuline -tubulation</i> of the proper wall of the chambers, and (3) the -peculiar <i>calcarine</i> relation of the canalization and tubulation, -here described and figured from specimens in the highest state -of preservation, showing the <i>least</i> evidence of any mineral -change.</p> -</div> - -<p><span class="pagenum"><a name="Page_206" id="Page_206">« 206 »</a></span></p> - -<div class="blockquot"> - -<p>"On the other hand, Professors King and Rowney began -their studies of Eozoic structure upon the Galway Ophite—a -rock which Sir Roderick Murchison described to me at the -time as having been so much ‘tumbled about,’ that he was -not at all sure of its geological position, and which exhibits -such obvious evidences of mineralization, with such an entire -absence of any vestige of organic structure, that I should -never for a moment have thought of crediting it with an organic -origin, but for the general resemblance of its serpentine-grains -to those of the ‘acervuline’ portion of the Canadian -Eozoon. They pronounced with the most positive certainty -upon the mineral origin of the Canadian Eozoon, before they -had subjected transparent sections of it to any of that careful -comparison with similar sections of recent Foraminifera, which -had been the basis of Dr. Dawson’s original determination, and -of my own subsequent confirmation, of its organic structure.</p> -</div> - -<div class="bbox2 fig_center" style="width: 650px;"> -<a name="Plate_VIII" id="Plate_VIII"></a> -<p class="tdr">Plate VIII.</p> - -<div class="fig_center" style="width: 413px;"> -<img src="images/plate_8.png" width="413" height="647" alt="" /> -</div> - -<p class="cap_center"><i>Eozoon and Chrysotile Veins, etc.</i></p> - -<p class="hanging"><span class="smcap">Fig. 1.</span>—Portion of two laminæ and intervening serpentine, with chrysotile -vein. (<i>a.</i>) Proper wall tubulated. (<i>b.</i>) Intermediate skeleton, with large -canals. (<i>c.</i>) Openings of small chamberlets filled with serpentine. (<i>s.</i>) Serpentine -filling chamber. (<i>s<sup>1</sup>.</i>) Vein of chrysotile, showing its difference from -the proper wall.</p> - -<p class="hanging"><span class="smcap">Fig. 2.</span>—Junction of a canal and the proper wall. Lettering as in Fig. 1.</p> - -<p class="hanging"><span class="smcap">Fig. 3.</span>—Proper wall shifted by a fault, and more recent chrysotile vein not -faulted. Lettering as in Fig. 1.</p> - -<p class="hanging"><span class="smcap">Fig. 4.</span>—Large and small canals filled with dolomite.</p> - -<p class="hanging"><span class="smcap">Fig. 5.</span>—Abnormally thick portion of intermediate skeleton, with large tubes -and small canals filled with dolomite.</p> -</div> - - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_207" id="Page_207">« 207 »</a></span></p> - - -<p class="caption2"><a name="CHAPTER_VIII" id="CHAPTER_VIII">CHAPTER VIII.</a><br /> - -THE DAWN-ANIMAL AS A TEACHER IN SCIENCE.</p> - - -<p>The thoughts suggested to the philosophical naturalist -by the contemplation of the dawn of life on our -planet are necessarily many and exciting, and the -subject has in it the materials for enabling the -general reader better to judge of some of the theories -of the origin of life agitated in our time. In this -respect our dawn-animal has scarcely yet had justice; -and we may not be able to render this in these pages. -Let us put it into the witness-box, however, and try to -elicit its testimony as to the beginnings of life.</p> - -<p>Looking down from the elevation of our physiological -and mental superiority, it is difficult to realize -the exact conditions in which life exists in creatures so -simple as the Protozoa. There may perhaps be higher -intelligences that find it equally difficult to realize how -life and reason can manifest themselves in such poor -houses of clay as those we inhabit. But placing ourselves -near to these creatures, and entering as it were -into sympathy with them, we can understand something -of their powers and feelings. In the first place it is -plain that they can vigorously, if roughly, exercise -those mechanical, chemical, and vegetative powers of -<span class="pagenum"><a name="Page_208" id="Page_208">« 208 »</a></span> -life which are characteristic of the animal. They can -seize, swallow, digest, and assimilate food; and, employing -its albuminous parts in nourishing their tissues, -can burn away the rest in processes akin to our respiration, -or reject it from their system. Like us, they -can subsist only on food which the plant has previously -produced; for in this world, from the beginning of -time, the plant has been the only organism which could -use the solar light and heat as forces to enable it to -turn the dead elements of matter into living, growing -tissues, and into organic compounds capable of nourishing -the animal. Like us, the Protozoa expend the food -which they have assimilated in the production of -animal force, and in doing so cause it to be oxidized, -or burnt away, and resolved again into dead matter. -It is true that we have much more complicated apparatus -for performing these functions, but it does not -follow that this gives us much real superiority, except -relatively to the more difficult conditions of our existence. -The gourmand who enjoys his dinner may have -no more pleasure in the act than the Amœba which -swallows a Diatom; and for all that the man knows of -the subsequent processes to which the food is subjected, -his interior might be a mass of jelly, with -extemporised vacuoles, like that of his humble fellow-animal. -The workman or the athlete has bones and -muscles of vastly complicated structure, but to him the -muscular act is as simple and unconscious a process as -the sending out of a pseudopod to a Protozoon. The -clay is after all the same, and there may be as much -<span class="pagenum"><a name="Page_209" id="Page_209">« 209 »</a></span> -credit to the artist in making a simple organism with -varied powers, as a more complex frame for doing nicer -work. It is a weakness of humanity to plume itself -on advantages not of its own making, and to treat its -superior gifts as if they were the result of its own -endeavours. The truculent traveller who illustrated -his boast of superiority over the Indian by comparing -his rifle with the bow and arrows of the savage, -was well answered by the question, “Can you make a -rifle?” and when he had to answer, “No,” by the -rejoinder, “Then I am at least better than you, for I -can make my bow and arrows.” The Amœba or the -Eozoon is probably no more than we its own creator; -but if it could produce itself out of vegetable matter -or out of inorganic substances, it might claim in so far -a higher place in the scale of being than we; and as -it is, it can assert equal powers of digestion, assimilation, -and motion, with much less of bodily mechanism.</p> - -<p>In order that we may feel, a complicated apparatus -of nerves and brain-cells has to be constructed and set -to work; but the Protozoon, without any distinct brain, -is all brain, and its sensation is simply direct. Thus -vision in these creatures is probably performed in a -rough way by any part of their transparent bodies, -and taste and smell are no doubt in the same case. -Whether they have any perception of sound as distinct -from the mere vibrations ascertained by touch, we do -not know. Here also we are not far removed above the -Protozoa, especially those of us to whom touch, seeing, -and hearing are mere feelings, without thought -<span class="pagenum"><a name="Page_210" id="Page_210">« 210 »</a></span> -or knowledge of the apparatus employed. We might -so far as well be Amœbas. As we rise higher we -meet with more differences. Yet it is evident that our -gelatinous fellow-being can feel pain, dread danger, -desire possessions, enjoy pleasure, and in a simple unconscious -way entertain many of the appetites and -passions that affect ourselves. The wonder is that -with so little of organization it can do so much. Yet, -perhaps, life can manifest itself in a broader and more -intense way where there is little organization; and a -highly strung and complex organism is not so much a -necessary condition of a higher life as a mere means of -better adapting it to its present surroundings. Those -philosophies which identify the thinking mind with the -material organism, must seem outrageous blunders to -an Amœba on the one hand, or to an angel on the -other, could either be enabled to understand them; -which, however, is not very probable, as they are too -intimately bound up with the mere prejudices incident -to the present condition of our humanity. In any case -the Protozoa teach us how much of animal function -may be fulfilled by a very simple organism, and warn -us against the fallacy that creatures of this simple -structure are necessarily nearer to inorganic matter, -and more easily developed from it than beings of more -complex mould.</p> - -<p>A similar lesson is taught by the complexity of their -skeletons. We speak in a crude unscientific way of -these animals accumulating calcareous matter, and -building up reefs of limestone. We must, however, -<span class="pagenum"><a name="Page_211" id="Page_211">« 211 »</a></span> -bear in mind that they are as dependent on their food -for the materials of their skeletons as we are, and that -their crusts grow in the interior of the sarcode just as -our bones do within our bodies. The provision even -for nourishing the interior of the skeleton by tubuli -and canals is in principle similar to that involved in -the Haversian canals, cells, and canalicules of bone. -The Amœba of course knows neither more nor less of -this than the average Englishman. It is altogether a -matter of unconscious growth. The process in the -Protozoa strikes some minds, however, as the more -wonderful of the two. It is, says an eminent -modern physiologist, a matter of “profound significance” -that this “particle of jelly [the sarcode of a -Foraminifer] is capable of guiding physical forces in -such a manner as to give rise to these exquisite and -almost mathematically arranged structures.” Respecting -the structures themselves there is no exaggeration -in this. No arch or dome framed by human skill is -more perfect in beauty or in the realization of mechanical -ideas than the tests of some Foraminifera, and -none is so complete and wonderful in its internal -structure. The particle of jelly, however, is a figure of -speech. The body of the humblest Foraminifer is -much more than this. It is an organism with divers -parts, as we have already seen in a previous chapter, -and it is endowed with the mysterious forces of life -which in it guide the physical forces, just as they do in -building up phosphate of lime in our bones, or indeed -just as the will of the architect does in building a -<span class="pagenum"><a name="Page_212" id="Page_212">« 212 »</a></span> -palace. The profound significance which this has, -reaches beyond the domain of the physical and vital, -even to the spiritual. It clings to all our conceptions -of living things: quite as much, for example, to the -evolution of an animal with all its parts from a one-celled -germ, or to the connection of brain-cells with -the manifestations of intelligence. Viewed in this -way, we may share with the author of the sentence I -have quoted his feeling of veneration in the presence -of this great wonder of animal life, “burning, and not -consumed,” nay, building up, and that in many and -beautiful forms. We may realize it most of all in the -presence of the organism which was perhaps the first -to manifest on our planet these marvellous powers. -We must, however, here also, beware of that credulity -which makes too many thinkers limit their conceptions -altogether to physical force in matters of this kind. -The merely materialistic physiologist is really in no -better position than the savage who quails before the -thunderstorm, or rejoices in the solar warmth, and seeing -no force or power beyond, fancies himself in the -immediate presence of his God. In Eozoon we must -discern not only a mass of jelly, but a being endowed -with that higher vital force which surpasses vegetable -life and also physical and chemical forces; and in this -animal energy we must see an emanation from a Will -higher than our own, ruling vitality itself; and this not -merely to the end of constructing the skeleton of a -Protozoon, but of elaborating all the wonderful developments -of life that were to follow in succeeding -<span class="pagenum"><a name="Page_213" id="Page_213">« 213 »</a></span> -ages, and with reference to which the production and -growth of this creature were initial steps. It is -this mystery of design which really constitutes the -“profound significance” of the foraminiferal skeleton.</p> - -<p>Another phenomenon of animality forced upon our -notice by the Protozoa is that of the conditions of life -in animals not individual, as we are, but aggregative -and cumulative in indefinite masses. What, for -instance, the relations to each other of the Polyps, -growing together in a coral mass, of the separate parts -of a Sponge, or the separate cells of a Foraminifer, or -of the sarcode mass of an indefinitely spread out -Stromatopora or Bathybius. In the case of the -Polyps, we may believe that there is special sensation -in the tentacles and oral opening of each individual, -and that each may experience hunger when in -want, or satisfaction when it is filled with food, and -that injuries to one part of the mass may indirectly -affect other parts, but that the nutrition of the whole -mass may be as much unfelt by the individual Polyps -as the processes going on in our own bones are by us. -So in the case of a large Sponge or Foraminifer, there -may be some special sensation in individual cells, -pseudopods, or segments, and the general sensation -may be very limited, while unconscious living powers -pervade the whole. In this matter of aggregation of -animals we have thus various grades. The Foraminifers -and Sponges present us with the simplest of all, -and that which most resembles the aggregation of -<span class="pagenum"><a name="Page_214" id="Page_214">« 214 »</a></span> -buds in the plant. The Polyps and complex Bryozoons -present a higher and more specialised type; and though -the bilateral symmetry which obtains in the higher -animals is of a different nature, it still at least reminds -us of that multiplication of similar parts which we see -in the lower grades of being. It is worthy of notice -here that the lower animals which show aggregative -tendencies present but imperfect indications, or none -at all, of bilateral symmetry. Their bodies, like those -of plants, are for the most part built up around a -central axis, or they show tendencies to spiral modes -of growth.</p> - -<p>It is this composite sort of life which is connected -with the main geological function of the Foraminifer. -While active sensation, appetite, and enjoyment pervade -the pseudopods and external sarcode of the mass, -the hard skeleton common to the whole is growing -within; and in this way the calcareous matter is -gradually removed from the sea water, and built up -in solid reefs, or in piles of loose foraminiferal shells. -Thus it is the aggregative or common life, alike in -Foraminifers as in Corals, that tends most powerfully -to the accumulation of calcareous matter; and those -creatures whose life is of this complex character are -best suited to be world-builders, since the result of -their growth is not merely a cemetery of their osseous -remains, but a huge communistic edifice, to which -multitudes of lives have contributed, and in which -successive generations take up their abode on the -remains of their ancestors. This process, so potent in -<span class="pagenum"><a name="Page_215" id="Page_215">« 215 »</a></span> -the progress of the earth’s geological history, began, -as far as we know, with Eozoon.</p> - -<p>Whether, then, in questioning our proto-foraminifer, -we have reference to the vital functions of its gelatinous -sarcode, to the complexity and beauty of its -calcareous test, or to its capacity for effecting great -material results through the union of individuals, we -perceive that we have to do, not with a low condition -of those powers which we designate life, but with the -manifestation of those powers through the means of a -simple organism; and this in a degree of perfection -which we, from our point of view, would have in the -first instance supposed impossible.</p> - -<p>If we imagine a world altogether destitute of life, we -still might have geological formations in progress. -Not only would volcanoes belch forth their liquid lavas -and their stones and ashes, but the waves and currents -of the ocean and the rains and streams on the land, -with the ceaseless decomposing action of the carbonic -acid of the atmosphere, would be piling up mud, sand, -and pebbles in the sea. There might even be some -formation of limestone taking place where springs -charged with bicarbonate of lime were oozing out on -the land or the bottom of the waters. But in such a -world all the carbon would be in the state of carbonic -acid, and all the limestone would either be diffused in -small quantities through various rocks or in limited -local beds, or in solution, perhaps as chloride of calcium, -in the sea. Dr. Hunt has given chemical -grounds for supposing that the most ancient seas were -<span class="pagenum"><a name="Page_216" id="Page_216">« 216 »</a></span> -largely supplied with this very soluble salt, instead of -the chloride of sodium, or common salt, which now -prevails in the sea-water.</p> - -<p>Where in such a world would life be introduced? -on the land or in the waters? All scientific probability -would say in the latter. The ocean is now -vastly more populous than the land. The waters -alone afford the conditions necessary at once for the -most minute and the grandest organisms, at once for -the simplest and for others of the most complex character. -Especially do they afford the best conditions -for those animals which subsist in complex communities, -and which aggregate large quantities of mineral -matter in their skeletons. So true is this that up to -the present time all the species of Protozoa and of the -animals most nearly allied to them are aquatic. Even -in the waters, however, plant life, though possibly in -very simple forms, must precede the animal.</p> - -<p>Let humble plants, then, be introduced in the waters, -and they would at once begin to use the solar light for -the purpose of decomposing carbonic acid, and forming -carbon compounds which had not before existed, and -which independently of vegetable life would never have -existed. At the same time lime and other mineral -substances present in the sea-water would be fixed in -the tissues of these plants, either in a minute state -of division, as little grains or Coccoliths, or in more -solid masses like those of the Corallines and Nullipores. -In this way a beginning of limestone formation -might be made, and quantities of carbonaceous -<span class="pagenum"><a name="Page_217" id="Page_217">« 217 »</a></span> -and bituminous matter, resulting from the decay of -marine plants might accumulate in the sea-bottom. -Now arises the opportunity for animal life. The -plants have collected stores of organic matter, and -their minute germs, along with microscopic species, are -floating everywhere in the sea. Nay, there may be -abundant examples of those Amœba-like germs of -aquatic plants, simulating for a time the life of the -animal, and then returning into the circle of vegetable -life. In these some might see precursors of the Protozoa, -though they are probably rather prophetic analogues -than blood relations. The plant has fulfilled -its function as far as the waters are concerned, and -now arises the opportunity for the animal. In what -form shall it appear? Many of its higher forms, those -which depend upon animal food or on the more complex -plants for subsistence, would obviously be unsuitable. -Further, the sea-water is still too much -saturated with saline matter to be fit for the higher -animals of the waters. Still further, there may be a -residue of internal heat forbidding coolness, and that -solution of free oxygen which is an essential condition -of existence to most of the modern animals. Something -must be found suitable for this saline, imperfectly -oxygenated, tepid sea. Something too is wanted -that can aid in introducing conditions more favourable -to higher life in the future. Our experience of the -modern world shows us that all these conditions can be -better fulfilled by the Protozoa than by any other -creatures. They can live now equally in those great -<span class="pagenum"><a name="Page_218" id="Page_218">« 218 »</a></span> -depths of ocean where the conditions are most unfavourable -to other forms of life, and in tepid unhealthy -pools overstocked with vegetable matter in a state of -putridity. They form a most suitable basis for higher -forms of life. They have remarkable powers of removing -mineral matters from the waters and of fixing -them in solid forms. So in the fitness of things -Eozoon is just what we need, and after it has spread -itself over the mud and rock of the primeval seas, and -built up extensive reefs therein, other animals may be -introduced capable of feeding on it, or of sheltering -themselves in its stony masses, and thus we have the -appropriate dawn of animal life.</p> - -<p>But what are we to say of the cause of this new -series of facts, so wonderfully superimposed upon the -merely vegetable and mineral? Must it remain to us -as an act of creation, or was it derived from some pre-existing -matter in which it had been potentially -present? Science fails to inform us, but conjectural -“phylogeny” steps in and takes its place. Haeckel, -the prophet of this new philosophy, waves his magic -wand, and simple masses of sarcode spring from inorganic -matter, and form diffused sheets of sea-slime, -from which are in time separated distinct Amœboid -and Foraminiferal forms. Experience, however, gives -us no facts whereon to build this supposition, and it -remains neither more nor less scientific or certain than -that old fancy of the Egyptians, which derived animals -from the fertile mud of the Nile.</p> - -<p>If we fail to learn anything of the origin of Eozoon, -<span class="pagenum"><a name="Page_219" id="Page_219">« 219 »</a></span> -and if its life-processes are just as inscrutable as those -of higher creatures, we can at least inquire as to its -history in geological time. In this respect we find in -the first place that the Protozoa have not had a monopoly -in their profession of accumulators of calcareous rock. -Originated by Eozoon in the old Laurentian time, -this process has been proceeding throughout the geological -ages; and while Protozoa, equally simple with -the great prototype of the race, have been and are -continuing its function, and producing new limestones -in every geological period, and so adding to the -volume of the successive formations, new workers of -higher grades have been introduced, capable of enjoying -higher forms of animal activity, and equally of -labouring at the great task of continent-building; of -existing, too, in seas less rich in mineral substances -than those of the Eozoic time, and for that very reason -better suited to higher and more skilled artists. It is -to be observed in connection with this, that as the work -of the Foraminifers has thus been assumed by others, -their size and importance have diminished, and the -grander forms of more recent times have some of them -been fain to build up their hard parts of cemented sand -instead of limestone.</p> - -<p>But we further find that, while the first though -not the only organic gatherers of limestone from the -ocean waters, they have had to do, not merely with -the formation of calcareous sediments, but also with -that of silicious deposits. The greenish silicate called -glauconite, or green-sand, is found to be associated -<span class="pagenum"><a name="Page_220" id="Page_220">« 220 »</a></span> -with much of the foraminiferal slime now accumulating -in the ocean, and also with the older deposits -of this kind now consolidated in chalks and similar -rocks. This name glauconite is, as Dr. Hunt has -shown, employed to designate not only the hydrous -silicate of iron and potash, which perhaps has the -best right to it, but also compounds which contain in -addition large percentages of alumina, or magnesia, -or both; and one glauconite from the Tertiary limestones -near Paris, is said to be a true serpentine, or -hydrous silicate of magnesia.<a name="FNanchor_53" id="FNanchor_53"></a><a href="#Footnote_53" class="fnanchor">[BA]</a> Now the association -of such substances with Foraminifera is not purely -accidental. Just as a fragment of decaying wood, -imbedded in sediment, has the power of decomposing -soluble silicates carried to it by water, and parting -with its carbon in the form of carbonic acid, in exchange -for the silica, and thus replacing, particle by -particle, the carbon of the wood with silicon, so -that at length it becomes petrified into a flinty mass, -so the sarcode of a Foraminifer, which is a more dense -kind of animal matter than is usually supposed, can -in like manner abstract silica from the surrounding -water or water-soaked sediment. From some peculiarity -in the conditions of the case, however, our -Protozoon usually becomes petrified with a hydrous -silicate instead of with pure silica. The favourable -conditions presented by the deep sea for the combination -of silica with bases, may perhaps account in part -<span class="pagenum"><a name="Page_221" id="Page_221">« 221 »</a></span> -for this. But whatever the cause, it is usual to find -fossil Foraminifera with their sarcode replaced by -such material. We also find beds of glauconite retaining -the forms of Foraminifera, while the calcareous -tests of these have been removed, apparently by acid -waters.</p> - -<div class="footnote"> - -<p><a name="Footnote_53" id="Footnote_53"></a><a href="#FNanchor_53"><span class="label">[BA]</span></a> Berthier, quoted by Hunt.</p> -</div> - -<p>One consideration which, though conjectural, deserves -notice, is connected with the food of these -humble animals. They are known to feed to a large -extent on minute plants, the Diatoms, and other -organisms having silica in their skeletons or cell-walls, -and consequently soluble silicates in their juices. -The silicious matter contained in these organisms is -not wanted by the Foraminifera for their own -skeletons, and will therefore be voided by them as -an excrementitious matter. In this way, where -Foraminifera greatly abound, there may be a large -production of soluble silica and silicates, in a condition -ready to enter into new and insoluble compounds, and -to fill the cavities and pores of dead shells. Thus -glauconite and even serpentine may, in a certain -sense, be a sort of foraminiferal coprolitic matter or -excrement. Of course it is not necessary to suppose -that this is the only source of such materials. They -may be formed in other ways; but I suggest this as at -least a possible link of connection.</p> - -<p>Whether or not the conjecture last mentioned has -any validity, there is another and most curious bond -of connection between oceanic Protozoa and silicious -deposits. Professor Wyville Thompson reports from -<span class="pagenum"><a name="Page_222" id="Page_222">« 222 »</a></span> -the <i>Challenger</i> soundings, that in certain areas -of the South Pacific the ordinary foraminiferal ooze -is replaced by a peculiar red clay, which he attributes -to the action of water laden with carbonic acid, in -removing all the lime, and leaving this red mud as a -sort of ash, composed of silica, alumina, and iron oxide. -Now this is in all probability a product of the decomposition -and oxidation of the glauconitic matter -contained in the ooze. Thus we learn that when areas -on which calcareous deposits have been accumulated -by Protozoa, are invaded by cold arctic or antarctic -waters charged with carbonic acid, the carbonate of -lime may be removed, and the glauconite left, or -even the latter may be decomposed, leaving silicious, -aluminous, and other deposits, which may be quite -destitute of any organic structures, or retain only -such remnants of them as have been accidentally or -by their more resisting character protected from destruction.<a name="FNanchor_54" id="FNanchor_54"></a><a href="#Footnote_54" class="fnanchor">[BB]</a> -In this way it may be possible that many -silicious rocks of the Laurentian and Primordial ages, -which now show no trace of organization, may be -<span class="pagenum"><a name="Page_223" id="Page_223">« 223 »</a></span> -indirectly products of the action of life. When -the recent deposits discovered by the <i>Challenger</i> -dredgings shall have been more fully examined, we -may perhaps have the means of distinguishing such -rocks, and thus of still further enlarging our conceptions -of the part played by Protozoa in the drama -of the earth’s history. In any case it seems plain -that beds of green-sand and similar hydrous silicates -may be the residue of thick deposits of foraminiferal -limestone or chalky matter, and that these -silicates may in their turn be oxidised and decomposed, -leaving beds of apparently inorganic clay. Such -beds may finally be consolidated and rendered crystalline -by metamorphism, and thus a great variety -of silicated rocks may result, retaining little or no -indication of any connection with the agency of life. -We can scarcely yet conjecture the amount of light -which these new facts may eventually throw on the -serpentine and other rocks of the Eozoic age. In the -meantime they open up a noble field to chemists and -microscopists.</p> - -<div class="footnote"> - -<p><a name="Footnote_54" id="Footnote_54"></a><a href="#FNanchor_54"><span class="label">[BB]</span></a> The “red chalk” of Antrim, and that of Speeton, contain -arenaceous Foraminifera and silicious casts of their shells, -apparently different from typical glauconite, and the extremely -fine ferruginous and argillaceous sediment of these chalks may -well be decomposed glauconitic matter like that of the South -Pacific. I have found these beds, the hard limestones of the -French Neocomian, and the altered green-sands of the Alps, -very instructive for comparison with the Laurentian limestones; -and they well deserve study by all interested in such -subjects.</p> -</div> - -<p>When the marvellous results of recent deep-sea -dredgings were first made known, and it was found -that chalky foraminiferal earth is yet accumulating in -the Atlantic, with sponges and sea urchins resembling -in many respects those whose remains exist in the -chalk, the fact was expressed by the statement that we -still live in the chalk period. Thus stated the conclusion -is scarcely correct. We do not live in the -chalk period, but the conditions of the chalk period -<span class="pagenum"><a name="Page_224" id="Page_224">« 224 »</a></span> -still exist in the deep sea. We may say more than -this. To some extent the conditions of the Laurentian -period still exist in the sea, except in so far as they -have been removed by the action of the Foraminifera -and other limestone builders. To those who can -realize the enormous lapse of time involved in the geological -history of the earth, this conveys an impression -almost of eternity in the existence of this oldest of all -the families of the animal kingdom.</p> - -<p>We are still more deeply impressed with this when -we bring into view the great physical changes which -have occurred since the dawn of life. When we consider -that the skeletons of Eozoon contribute to form -the oldest hills of our continents; that they have been -sealed up in solid marble, and that they are associated -with hard crystalline rocks contorted in the most fantastic -manner; that these rocks have almost from the -beginning of geological time been undergoing waste to -supply the material of new formations; that they have -witnessed innumerable subsidences and elevations of -the continents; and that the greatest mountain chains -of the earth have been built up from the sea since -Eozoon began to exist,—we acquire a most profound -impression of the persistence of the lower forms of animal -life, and know that mountains may be removed -and continents swept away and replaced, before the -least of the humble gelatinous Protozoa can finally -perish. Life may be a fleeting thing in the individual, -but as handed down through successive generations -of beings, and as a constant animating power in -<span class="pagenum"><a name="Page_225" id="Page_225">« 225 »</a></span> -successive organisms, it appears, like its Creator, -eternal.</p> - -<p>This leads to another and very serious question. -How long did lineal descendants of Eozoon exist, and -do they still exist? We may for the present consider -this question apart from ideas of derivation and elevation -into higher planes of existence. Eozoon as a -species and even as a genus may cease to exist with -the Eozoic age, and we have no evidence whatever -that Archæocyathus, Stromatopora, or Receptaculites -are its modified descendants. As far as their structures -inform us, they may as much claim to be original -creations as Eozoon itself. Still descendants of Eozoon -may have continued to exist, though we have not yet -met with them. I should not be surprised to hear of -a veritable specimen being some day dredged alive in -the Atlantic or the Pacific. It is also to be observed -that in animals so simple as Eozoon many varieties -may appear, widely different from the original. In -these the general form and habit of life are the most -likely things to change, the minute structures much -less so. We need not, therefore, be surprised to find -its descendants diminishing in size or altering in -general form, while the characters of the fine tubulation -and of the canal system would remain. We need -not wonder if any sessile Foraminifer of the Nummuline -group should prove to be a descendant of Eozoon. -It would be less likely that a Sponge or a Foraminifer -of the Rotaline type should originate from it. If one -could only secure a succession of deep-sea limestones -<span class="pagenum"><a name="Page_226" id="Page_226">« 226 »</a></span> -with Foraminifers, extending all the way from the -Laurentian to the present time, I can imagine nothing -more interesting than to compare the whole series, -with the view of ascertaining the limits of descent with -variation, and the points where new forms are introduced. -We have not yet such a series, but it may be -obtained; and as Foraminifera are eminently cosmopolitan, -occurring over vastly wide areas of sea-bottom, -and are very variable, they would afford a better test -of theories of derivation than any that can be obtained -from the more locally distributed and less variable animals -of higher grade. I was much struck with this -recently, in examining a series of Foraminifera from -the Cretaceous of Manitoba, and comparing them with -the varietal forms of the same species in the interior of -Nebraska, 500 miles to the south, and with those of -the English chalk and of the modern seas. In all -these different times and places we had the same species. -In all they existed under so many varietal forms -passing into each other, that in former times every -species had been multiplied into several. Yet in all, -the identical varietal forms were repeated with the -most minute markings alike. Here were at once -constancy the most remarkable and variations the -most extensive. If we dwell on the one to the exclusion -of the other, we reach only one-sided conclusions, -imperfect and unsatisfactory. By taking both in connection -we can alone realize the full significance of the -facts. We cannot yet obtain such series for all geological -time; but it may even now be worth while to -<span class="pagenum"><a name="Page_227" id="Page_227">« 227 »</a></span> -inquire, What do we know as to any modification in -the case of the primeval Foraminifers, whether with -reference to the derivation from them of other Protozoa -or of higher forms of life?</p> - -<p>There is no link whatever in geological fact to connect -Eozoon with any of the Mollusks, Radiates, or -Crustaceans of the succeeding Primordial. What may -be discovered in the future we cannot conjecture; but -at present these stand before us as distinct creations. -It would of course be more probable that Eozoon -should be the ancestor of some of the Foraminifera of -the Primordial age, but strangely enough it is very -dissimilar from all these except Stromatopora; and -here, as already stated, the evidence of minute structure -fails to a great extent, and Eozoon Bavaricum of -the Huronian age scarcely helps to bridge over the gap -which yawns in our imperfect geological record. Of -actual facts, therefore, we have none; and those evolutionists -who have regarded the dawn-animal as an -evidence in their favour, have been obliged to have -recourse to supposition and assumption.</p> - -<p>Taking the ground of the derivationist, it is convenient -to assume (1) that Eozoon was either the first -or nearly the first of animals, and that, being a Protozoan -of simple structure, it constitutes an appropriate -beginning of life; (2) that it originated from some -unexplained change in the protoplasmic or albuminous -matter of some humble plant, or directly from inorganic -matter, or at least was descended from some -creature only a little more simple which had being in -<span class="pagenum"><a name="Page_228" id="Page_228">« 228 »</a></span> -this way; (3) that it had in itself unlimited capacities -for variation and also for extension in time; (4) that it -tended to multiply rapidly, and at last so to occupy the -ocean that a struggle for existence arose; (5) that -though at first, from the very nature of its origin, -adapted to the conditions of the world, yet as these -conditions became altered by physical changes, it -was induced to accommodate itself to them, and so -to pass into new species and genera, until at last -it appeared in entirely new types in the Primordial -fauna.</p> - -<p>These assumptions are, with the exception of the -first two, merely the application to Eozoon of what -have been called the Darwinian laws of multiplication, -of limited population, of variation, of change of -physical conditions, and of equilibrium of nature. If -otherwise proved, and shown to be applicable to creatures -like Eozoon, of course we must apply them to it; -but in so far as that creature itself is concerned they -are incapable of proof, and some of them contrary to -such evidence as we have. We have, for example, no -connecting link between Eozoon and any form of vegetable -life. Its structures are such as to enable us at once -to assign it to the animal kingdom, and if we seek for -connecting links between the lower animals and plants -we have to look for them in the modern waters. We -have no reason to conclude that Eozoon could multiply -so rapidly as to fill all the stations suitable for it, and -to commence a struggle for existence. On the contrary, -after the lapse of untold ages the conditions for -<span class="pagenum"><a name="Page_229" id="Page_229">« 229 »</a></span> -the life of Foraminifers still exist over two-thirds of -the surface of the earth. In regard to variation, we -have, it is true, evidence of the wide range of varieties -of species in Protozoa, within the limits of the group, -but none whatever of any tendency to pass into other -groups. Nor can it be proved that the conditions of -the ocean were so different in Cambrian or Silurian -times as to preclude the continued and comfortable -existence of Eozoon. New creatures came in which -superseded it, and new conditions more favourable in -proportion to these new creatures, but neither the new -creatures nor the new conditions were necessarily or -probably connected with Eozoon, any farther than that -it may have served newer tribes of animals for food, -and may have rid the sea of some of its superfluous -lime in their interest. In short, the hypothesis of evolution -will explain the derivation of other animals from -Eozoon if we adopt its assumptions, just as it will in -that case explain anything else, but the assumptions -are improbable, and contrary to such facts as we know.</p> - -<p>Eozoon itself, however, bears some negative though -damaging testimony against evolution, and its argument -may be thus stated in what we may imagine to -be its own expressions:—"I, Eozoon Canadense, being -a creature of low organization and intelligence, and of -practical turn, am no theorist, but have a lively appreciation -of such facts as I am able to perceive. I -found myself growing upon the sea-bottom, and know -not whence I came. I grew and flourished for ages, -and found no let or hindrance to my expansion, and -<span class="pagenum"><a name="Page_230" id="Page_230">« 230 »</a></span> -abundance of food was always floated to me without -my having to go in search of it. At length a change -came. Certain creatures with hard snouts and jaws -began to prey on me. Whence they came I know not; -I cannot think that they came from the germs which I -had dispersed so abundantly throughout the ocean. -Unfortunately, just at the same time lime became a -little less abundant in the waters, perhaps because of -the great demands I myself had made, and thus it was -not so easy as before to produce a thick supplemental -skeleton for defence. So I had to give way. I have -done my best to avoid extinction; but it is clear that I -must at length be overcome, and must either disappear -or subside into a humbler condition, and that other -creatures better provided for the new conditions of the -world must take my place." In such terms we may -suppose that this patriarch of the seas might tell his -history, and mourn his destiny, though he might -also congratulate himself on having in an honest -way done his duty and fulfilled his function in the -world, leaving it to other and perhaps wiser creatures -to dispute as to his origin and fate, while much -less perfectly fulfilling the ends of their own existence.</p> - -<p>Thus our dawn-animal has positively no story to -tell as to his own introduction or his transmutation -into other forms of existence. He leaves the mystery -of creation where it was; but in connection with the -subsequent history of life we can learn from him a -little as to the laws which have governed the succession -<span class="pagenum"><a name="Page_231" id="Page_231">« 231 »</a></span> -of animals in geological time. First, we may learn -that the plan of creation has been progressive, that there -has been an advance from the few, low, and generalized -types of the primæval ocean to the more numerous, -higher, and more specialized types of more recent -times. Secondly, we learn that the lower types, when -first introduced, and before they were subordinated to -higher forms of life, existed in some of their grandest -modifications as to form and complexity, and that in -succeeding ages, when higher types were replacing -them, they were subjected to decay and degeneracy. -Thirdly, we learn that while the species has a limited -term of existence in geological time, any grand type of -animal existence, like that of the Foraminifera or -Sponges, for example, once introduced, continues and -finds throughout all the vicissitudes of the earth some -appropriate residence. Fourthly, as to the mode of -introduction of new types, or whether such creatures -as Eozoon had any direct connection with the subsequent -introduction of mollusks, worms, or crustaceans, -it is altogether silent, nor can it predict anything as to -the order or manner of their introduction.</p> - -<p>Had we been permitted to visit the Laurentian seas, -and to study Eozoon and its contemporary Protozoa -when alive, it is plain that we could not have foreseen -or predicted from the consideration of such organisms -the future development of life. No amount of study -of the prototypal Foraminifer could have led us distinctly -to the conception of even a Sponge or a Polyp, -much less of any of the higher animals. Why is this? -<span class="pagenum"><a name="Page_232" id="Page_232">« 232 »</a></span> -The answer is that the improvement into such higher -types does not take place by any change of the elementary -sarcode, either in those chemical, mechanical, -or vital properties which we can study, but in the adding -to it of new structures. In the Sponge, which is -perhaps the nearest type of all, we have the movable -pulsating cilium and true animal cellular tissue, and -along with this the spicular or fibrous skeleton, these -structures leading to an entire change in the mode of -life and subsistence. In the higher types of animals -it is the same. Even in the highest we have white -blood-corpuscles and germinal matter, which, in so far -as we know, carry on no higher forms of life than -those of an Amœba; but they are now made subordinate -to other kinds of tissue, of great variety and -complexity, which never have been observed to arise -out of the growth of any Protozoon. There would be -only a very few conceivable inferences which the highest -finite intelligence could deduce as to the development -of future and higher animals. He might infer -that the foraminiferal sarcode, once introduced, might -be the substratum or foundation of other but unknown -tissues in the higher animals, and that the Protozoan -type might continue to subsist side by side with higher -forms of living things as they were successively introduced. -He might also infer that the elevation of the -animal kingdom would take place with reference to -those new properties of sensation and voluntary motion -in which the humblest animals diverge from the life of -the plant.</p> - -<p><span class="pagenum"><a name="Page_233" id="Page_233">« 233 »</a></span></p> - -<p>It is important that these points should be clearly -before our minds, because there has been current of -late among naturalists a loose way of writing with -reference to them, which seems to have imposed on -many who are not naturalists. It has been said, for -example, that such an organism as Eozoon may include -potentially all the structures and functions of the -higher animals, and that it is possible that we might -be able to infer or calculate all these with as much -certainty as we can calculate an eclipse or any other -physical phenomenon. Now, there is not only no foundation -in fact for these assertions, but it is from our -present standpoint not conceivable that they can ever -be realized. The laws of inorganic matter give no -data whence any <i>á priori</i> deductions or calculations -could be made as to the structure and vital forces of -the plant. The plant gives no data from which we can -calculate the functions of the animal. The Protozoon -gives no data from which we can calculate the specialties -of the Mollusc, the Articulate, or the Vertebrate. -Nor unhappily do the present conditions of life of -themselves give us any sure grounds for predicting the -new creations that may be in store for our old planet. -Those who think to build a philosophy and even a -religion on such data are mere dreamers, and have no -scientific basis for their dogmas. They are more -blind guides than our primæval Protozoon himself -would be, in matters whose real solution lies in the -harmony of our own higher and immaterial nature -with the Being who is the author of all life—the -<span class="pagenum"><a name="Page_234" id="Page_234">« 234 »</a></span> -Father “from whom every family in heaven and -earth is named.”</p> - -<p>While this work was going through the press, Lyell, -the greatest geological thinker of our time, passed -away. In the preceding pages I have refrained from -quoting the many able geologists and biologists who -have publicly accepted the evidence of the animal -nature of Eozoon as sufficient, preferring to rest my -case on its own merits rather than on authority; but -it is due to the great man whose loss we now mourn, -to say that, before the discovery of Eozoon, he had -expressed on general grounds his anticipation that -fossils would be found in the rocks older than the so-called -Primordial Series, and that he at once admitted -the organic nature of Eozoon, and introduced it, as a -fossil, into the edition of his Elements of Geology published -in the same year in which it was described.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_235" id="Page_235">« 235 »</a></span></p> - - - - -<p class="caption2"><a name="APPENDIX" id="APPENDIX">APPENDIX.</a><br /> - -CHARACTERS OF LAURENTIAN AND HURONIAN PROTOZOA.</p> - - -<p>It may be useful to students to state the technical characters -of Eozoon, in addition to the more popular and general -descriptions in the preceding pages.</p> - - -<p class="caption3"><i>Genus</i> EOZOON.</p> - -<p>Foraminiferal skeletons, with irregular and often confluent -cells, arranged in concentric and horizontal laminæ, or sometimes -piled in an acervuline manner. Septal orifices irregularly -disposed. Proper wall finely tubulated. Intermediate skeleton -with branching canals.</p> - - -<p class="caption3"><span class="smcap">Eozoon Canadense</span>, <i>Dawson</i>.</p> - -<p>In rounded masses or thick encrusting sheets, frequently of -large dimensions. Typical structure stromatoporoid, or with -concentric calcareous walls, frequently uniting with each other, -and separating flat chambers, more or less mammillated, and -spreading into horizontal lobes and small chamberlets; -chambers often confluent and crossed by irregular calcareous -pillars connecting the opposite walls. Upper part often composed -of acervuline chambers of rounded forms. Proper wall -tubulated very finely. Intermediate skeleton largely developed, -especially at the lower part, and traversed by large -canals, often with smaller canals in their interstices. Lower -laminæ and chambers often three millimetres in thickness. -Upper laminæ and chambers one millimetre or less. Age -Laurentian and perhaps Huronian.</p> - -<p><span class="pagenum"><a name="Page_236" id="Page_236">« 236 »</a></span></p> - -<p><i>Var.</i> <span class="smcap">MINOR</span>.—Supplemental skeleton wanting, except near -the base, and with very fine canals. Laminæ of sarcode much -mammillated, thin, and separated by very thin walls. Probably -a depauperated variety.</p> - -<p><i>Var.</i> <span class="smcap">ACERVULINA</span>.—In oval or rounded masses, wholly acervuline. -Cells rounded; intermediate skeleton absent or much -reduced; cell-walls tubulated. This may be a distinct species, -but it closely resembles the acervuline parts of the ordinary -form.</p> - - -<p class="caption3"><span class="smcap">Eozoon Bavaricum</span>, <i>Gümbel</i>.</p> - -<p>Composed of small acervuline chambers, separated by contorted -walls, and associated with broad plate-like chambers -below. Large canals in the thicker parts of the intermediate -skeleton. Differs from <i>E. Canadense</i> in its smaller and more -contorted chambers. Age probably Huronian.</p> - - -<p class="caption3"><i>Genus</i> ARCHÆOSPHERINA.</p> - -<p>A provisional genus, to include rounded solitary chambers, -or globigerine assemblages of such chambers, with the cell-wall -surrounding them tubulated as in Eozoon. They may be -distinct organisms, or gemmæ or detached fragments of -Eozoon. Some of them much resemble the bodies figured by -Dr. Carpenter, as gemmæ or ova and primitive chambers of -Orbitolites. They are very abundant on some of the strata -surfaces of the limestone at Côte St. Pierre. Age Lower -Laurentian.</p> - -<p><span class="pagenum"><a name="Page_236a" id="Page_236a">« 236<i>a</i> »</a></span></p> - - -<p class="caption3">SYSTEMATIC POSITION OF EOZOON.</p> - -<p>The unsettled condition of the classification of the Protozoa, -and our absolute ignorance of the animal matter of Eozoon, -render it difficult to make any statement on this subject more -definite than the somewhat vague intimations given in the -text. My own views at present, based on the study of recent -and fossil forms, and of the writings of Carpenter, Max -Schultze, Carter, Wallich, Haeckel, and Clarepede, may be -stated, though with some diffidence, as follows:—</p> - -<div class="blockquot"> - -<p>I. The class <i>Rhizopoda</i> includes all the sarcodous animals -whose only external organs are pseudopodia, and is the lowest -class in the animal kingdom. Immediately above it are the -classes of the Sponges and of the flagellate and ciliate -Infusoria, which rise from it like two diverging branches.</p> - -<p>II. The group of Rhizopods, as thus defined, includes -three leading <i>orders</i>, which, in descending grade, are as -follows:—</p> - -<div class="blockquot"> - -<p>(<i>a</i>) <i>Lobosa</i>, or Amœboid Rhizopods, including those with -distinct nucleus and pulsating vesicle, and thick -lobulate pseudopodia—naked, or in membranous -coverings.</p> - -<p>(<i>b</i>) <i>Radiolaria</i>, or Polycistius and their allies, including those -with thread-like pseudopodia, with or without -a nucleus, and with the skeleton, when present, -silicious.</p> - -<p>(<i>c</i>) <i>Reticularia</i>, or Foraminifera and their allies, including -those with thread-like and reticulating pseudopodia, -with granular matter instead of a nucleus, -and with calcareous, membranous, or arenaceous -skeletons.</p> - -<p>The place of <i>Eozoon</i> will be in the lowest order, <i>Reticularia</i>.</p> -</div> - -<p>III. The order <i>Reticularia</i> may be farther divided into two -<i>sub-orders</i>, as follows:—</p> - -<p><span class="pagenum"><a name="Page_236b" id="Page_236b">« 236<i>b</i> »</a></span></p> - -<div class="blockquot"> - -<p>(<i>a</i>) <i>Perforata</i>—having calcareous skeletons penetrated with -pores.</p> - -<p>(<i>b</i>) <i>Imperforata</i>—having calcareous, membranous, or arenaceous -skeletons, without pores.</p> -</div> - -<p>The place of Eozoon will be in the higher sub-order, -<i>Perforata</i>.</p> - -<p>IV. The sub-order <i>Perforata</i> includes three <i>families</i>—the -<i>Nummulinidæ</i>, <i>Globigerinidæ</i>, and <i>Lagemdæ</i>. Of these Carpenter -regards the Nummulinidæ as the highest in rank.</p> -</div> - -<p>The place of Eozoon will be in the family <i>Nummulinidæ</i>, or -between this and the next family. This oldest known Protozoon -would thus belong to the highest family in the highest -sub-order of the lowest class of animals.</p> - -<p><span class="pagenum"><a name="Page_236c" id="Page_236c">« 236<i>c</i> »</a></span></p> - - -<p class="caption3">THE LATE SIR WILLIAM E. LOGAN.</p> - -<p>When writing the dedication of this work, I little thought -that the eminent geologist and valued friend to whom it gave -me so much pleasure to tender this tribute of respect, would -have passed away before its publication. But so it is, and we -have now to mourn, not only Lyell, who so frankly accepted the -evidence in favour of Eozoon, but Logan, who so boldly from -the first maintained its true nature as a fossil. This boldness -on his part is the more remarkable and impressive, from the -extreme caution by which he was characterized, and which -induced him to take the most scrupulous pains to verify every -new fact before committing himself to it. Though Sir -William’s early work in the Welsh coal-fields, his organization -and management of the Survey of Canada, and his reducing to -order for the first time all the widely extended Palæozoic -formations of that great country, must always constitute -leading elements in his reputation, I think that in nothing -does he deserve greater credit than in the skill and genius -with which he attacked the difficult problem of the Laurentian -rocks, unravelled their intricacies, and ascertained their true -nature as sediments, and the leading facts of their arrangement -and distribution. The discovery of Eozoon was one of -the results of this great work; and it was the firm conviction -to which Sir William had attained of the sedimentary character -of the rocks, which rendered his mind open to the -evidence of these contained fossils, and induced him even to -expect the discovery of them.</p> - -<p>This would not be the proper place to dwell on the general -character and work of Sir William Logan, but I cannot close -without referring to his untiring industry, his enthusiasm in -the investigation of nature, his cheerful and single-hearted -disposition, his earnest public spirit and patriotism—qualities -which won for him the regard even of those who could little -appreciate the details of his work, and which did much to -enable him to attain to the success which he achieved.</p> - -<hr class="chap" /> - -<p><span class="pagenum"><a name="Page_237" id="Page_237">« 237 »</a></span></p> - - - - -<p class="caption2"><a name="INDEX" id="INDEX">INDEX.</a></p> - -<p class="caption3"><a href="#alpha_a">A</a> | <a href="#alpha_b">B</a> | <a href="#alpha_c">C</a> | <a href="#alpha_d">D</a> | <a href="#alpha_e">E</a> | <a href="#alpha_f">F</a> | <a href="#alpha_g">G</a> | <a href="#alpha_h">H</a><br /> -<a href="#alpha_i">I</a> | <a href="#alpha_i">I</a> | <a href="#alpha_j">J</a> | <a href="#alpha_k">K</a> | <a href="#alpha_l">L</a> | <a href="#alpha_m">M</a> | <a href="#alpha_n">N</a> | <a href="#alpha_o">O</a><br /> -<a href="#alpha_p">P</a> | <a href="#alpha_r">R</a> | <a href="#alpha_s">S</a> | <a href="#alpha_t">T</a> | <a href="#alpha_v">V</a> | <a href="#alpha_w">W</a></p> - - -<div class="Index"> -<a name="alpha_a" id="alpha_a"></a>Acervuline explained, <a href="#Page_66">66</a>.<br /> -Acervuline Variety of Eozoon, <a href="#Page_135">135</a>.<br /> -Aggregative Growth of Animals, <a href="#Page_213">213</a>.<br /> -Aker Limestone, <a href="#Page_197">197</a>.<br /> -Amity Limestone, <a href="#Page_197">197</a>.<br /> -Amœba described, <a href="#Page_59">59</a>.<br /> -Annelid Burrows, <a href="#Page_133">133</a>, <a href="#Page_139">139</a>.<br /> -Archæospherinæ, <a href="#Page_137">137</a>, <a href="#Page_148">148</a>.<br /> -Archæocyathus, <a href="#Page_151">151</a>.<br /> -Arisaig, Supposed Eozoon of, <a href="#Page_140">140</a>.<br /> -<br /> -<a name="alpha_b" id="alpha_b"></a>Bathybius, <a href="#Page_65">65</a>.<br /> -Bavaria, Eozoon of, <a href="#Page_148">148</a>.<br /> -Beginning of Life, <a href="#Page_215">215</a>.<br /> -Billings, Mr.,—referred to, <a href="#Page_41">41</a>;<br /> -<span style="margin-left: 2em;">on Archæocyathus, <a href="#Page_151">151</a>;</span><br /> -<span style="margin-left: 2em;">on Receptaculites, <a href="#Page_163">163</a>.</span><br /> -<br /> -<a name="alpha_c" id="alpha_c"></a>Calumet, Eozoon of, <a href="#Page_38">38</a>.<br /> -Calcarina, <a href="#Page_74">74</a>.<br /> -Calcite filling Tubes of Eozoon, <a href="#Page_98">98</a>.<br /> -Canal System of Eozoon, <a href="#Page_40">40</a>, <a href="#Page_66">66</a>, <a href="#Page_107">107</a>, <a href="#Page_176">176</a>, <a href="#Page_181">181</a>.<br /> -Carpenter—referred to, <a href="#Page_41">41</a>;<br /> -<span style="margin-left: 2em;">on Eozoon, <a href="#Page_82">82</a>;</span><br /> -<span style="margin-left: 2em;">Reply to Carter, <a href="#Page_204">204</a>.</span><br /> -Caunopora, <a href="#Page_158">158</a>.<br /> -Chrysotile Veins, <a href="#Page_107">107</a>, <a href="#Page_180">180</a>.<br /> -Chemistry of Eozoon, <a href="#Page_199">199</a>.<br /> -Coccoliths, <a href="#Page_70">70</a>.<br /> -Cœnostroma, <a href="#Page_158">158</a>.<br /> -Contemporaries of Eozoon, <a href="#Page_127">127</a>.<br /> -Côte St. Pierre, <a href="#Page_20">20</a>.<br /> -<br /> -<a name="alpha_d" id="alpha_d"></a>Derivation applied to Eozoon, <a href="#Page_225">225</a>.<br /> -Discovery of Eozoon, <a href="#Page_35">35</a>.<br /> -<br /> -<a name="alpha_e" id="alpha_e"></a>Eozoic Time, <a href="#Page_7">7</a>.<br /> -Eozoon,—Discovery of, <a href="#Page_35">35</a>;<br /> -<span style="margin-left: 2em;">Structure of, <a href="#Page_65">65</a>;</span><br /> -<span style="margin-left: 2em;">Growth of, <a href="#Page_70">70</a>;</span><br /> -<span style="margin-left: 2em;">Fragments of, <a href="#Page_74">74</a>;</span><br /> -<span style="margin-left: 2em;">Description of, <a href="#Page_65">65</a>, 77 (also Appendix);</span><br /> -<span style="margin-left: 2em;">Note on by Dr. Carpenter, <a href="#Page_82">82</a>;</span><br /> -<span style="margin-left: 2em;">Thickened Walls of, <a href="#Page_66">66</a>;</span><br /> -<span style="margin-left: 2em;">Preservation of, <a href="#Page_100">100</a>;</span><br /> -<span style="margin-left: 2em;">Pores filled with Calcite, <a href="#Page_97">97</a>, <a href="#Page_109">109</a>;</span><br /> -<span style="margin-left: 2em;">with Pyroxene, <a href="#Page_108">108</a>;</span><br /> -<span style="margin-left: 2em;">with Serpentine, <a href="#Page_101">101</a>;</span><br /> -<span style="margin-left: 2em;">with Dolomite, <a href="#Page_109">109</a>;</span><br /> -<span style="margin-left: 2em;">in Limestone, <a href="#Page_110">110</a>;</span><br /> -<span style="margin-left: 2em;">Defective Specimens of, <a href="#Page_113">113</a>;</span><br /> -<span style="margin-left: 2em;">how Mineralized, <a href="#Page_102">102</a>, <a href="#Page_116">116</a>;</span><br /> -<span style="margin-left: 2em;">its Contemporaries, <a href="#Page_127">127</a>;</span><br /> -<span style="margin-left: 2em;">Acervuline Variety of, <a href="#Page_135">135</a>;</span><br /> -<span style="margin-left: 2em;">Variety <i>Minor</i> of, <a href="#Page_135">135</a>;</span><br /> -<span style="margin-left: 2em;">Acadianum, <a href="#Page_140">140</a>;</span><br /> -<span style="margin-left: 2em;">Bavaricum, <a href="#Page_148">148</a>;</span><br /> -<span style="margin-left: 2em;">Localities of, <a href="#Page_166">166</a>;</span><br /> -<span style="margin-left: 2em;">Harmony of with other Fossils, <a href="#Page_171">171</a>;</span><br /> -<span style="margin-left: 2em;">Summary of evidence relating to, <a href="#Page_176">176</a>.</span><br /> -<br /> -<a name="alpha_f" id="alpha_f"></a>Faulted Eozoon, <a href="#Page_182">182</a>.<br /> -Foraminifera, Notice of, <a href="#Page_61">61</a>.<br /> -<span class="pagenum"><a name="Page_238" id="Page_238">« 238 »</a></span><br /> -Fossils, how Mineralized, <a href="#Page_93">93</a>.<br /> -Fusulina, <a href="#Page_74">74</a>.<br /> -<br /> -<a name="alpha_g" id="alpha_g"></a>Glauconite, <a href="#Page_100">100</a>, <a href="#Page_125">125</a>, <a href="#Page_220">220</a>.<br /> -Graphite of Laurentian, <a href="#Page_18">18</a>, <a href="#Page_27">27</a>.<br /> -Green-sand, <a href="#Page_99">99</a>.<br /> -Grenville, Eozoon of, <a href="#Page_38">38</a>.<br /> -Gümbel on Laurentian Fossils, <a href="#Page_124">124</a>;<br /> -<span style="margin-left: 2em;">on Eozoon Bavaricum, <a href="#Page_141">141</a>.</span><br /> -<br /> -<a name="alpha_h" id="alpha_h"></a>Hastings, Rocks of, <a href="#Page_57">57</a>.<br /> -History of Discovery of Eozoon, <a href="#Page_35">35</a>.<br /> -Honeyman, Dr., referred to, <a href="#Page_140">140</a>.<br /> -Hunt, Dr. Sterry, referred to, <a href="#Page_35">35</a>;<br /> -<span style="margin-left: 2em;">on Mineralization of Eozoon, <a href="#Page_115">115</a>;</span><br /> -<span style="margin-left: 2em;">on Silurian Fossils infiltrated with Silicates, <a href="#Page_121">121</a>;</span><br /> -<span style="margin-left: 2em;">on Minerals of the Laurentian, <a href="#Page_123">123</a>;</span><br /> -<span style="margin-left: 2em;">on Laurentian Life, <a href="#Page_27">27</a>;</span><br /> -<span style="margin-left: 2em;">his Reply to Objections, <a href="#Page_199">199</a>.</span><br /> -Huronian Rocks, <a href="#Page_9">9</a>.<br /> -<br /> -<a name="alpha_i" id="alpha_i"></a>Intermediate Skeleton, <a href="#Page_64">64</a>.<br /> -Iron Ores of Laurentian, <a href="#Page_19">19</a>.<br /> -<br /> -<a name="alpha_j" id="alpha_j"></a>Jones, Prof. T. Rupert, on Eozoon, <a href="#Page_42">42</a>.<br /> -<br /> -<a name="alpha_k" id="alpha_k"></a>King, Prof., his Objections, <a href="#Page_184">184</a>.<br /> -<br /> -<a name="alpha_l" id="alpha_l"></a>Labrador Feldspar, <a href="#Page_13">13</a>.<br /> -Laurentian Rocks, <a href="#Page_7">7</a>;<br /> -<span style="margin-left: 2em;">Fossils of, <a href="#Page_130">130</a>;</span><br /> -<span style="margin-left: 2em;">Graphite of, <a href="#Page_18">18</a>, <a href="#Page_27">27</a>;</span><br /> -<span style="margin-left: 2em;">Iron Ores of, <a href="#Page_19">19</a>;</span><br /> -<span style="margin-left: 2em;">Limestones of, <a href="#Page_17">17</a>.</span><br /> -Limestones, Laurentian, <a href="#Page_17">17</a>;<br /> -<span style="margin-left: 2em;">Silurian, <a href="#Page_98">98</a>.</span><br /> -Localities of Eozoon, <a href="#Page_166">166</a>.<br /> -Loftusia, <a href="#Page_164">164</a>.<br /> -Logan, Sir Wm., referred to, <a href="#Page_36">36</a>;<br /> -<span style="margin-left: 2em;">on Laurentian, <a href="#Page_24">24</a>;</span><br /> -<span style="margin-left: 2em;">on Nature of Eozoon, <a href="#Page_37">37</a>;</span><br /> -<span style="margin-left: 2em;">Geological Relations of Eozoon, <a href="#Page_48">48</a>;</span><br /> -<span style="margin-left: 2em;">on Additional Specimens of Eozoon, <a href="#Page_52">52</a>.</span><br /> -Loganite in Eozoon, <a href="#Page_36">36</a>, <a href="#Page_102">102</a>.<br /> -Lowe, Mr., referred to, <a href="#Page_38">38</a>.<br /> -Long Lake, Specimens from, <a href="#Page_91">91</a>.<br /> -Lyell, Sir C., on Eozoon, <a href="#Page_234">234</a>.<br /> -<br /> -<a name="alpha_m" id="alpha_m"></a>Madoc, Specimens from, <a href="#Page_132">132</a>.<br /> -Maps of Laurentian, <a href="#Page_7">7</a>, <a href="#Page_16">16</a>.<br /> -MacMullen, Mr., referred to, <a href="#Page_37">37</a>.<br /> -Metamorphism of Rocks, <a href="#Page_13">13</a>, <a href="#Page_34">34</a>.<br /> -Mineralization of Eozoon, <a href="#Page_101">101</a>;<br /> -<span style="margin-left: 2em;">of Fossils, <a href="#Page_93">93</a>;</span><br /> -<span style="margin-left: 2em;">Hunt on, <a href="#Page_115">115</a>.</span><br /> -<br /> -<a name="alpha_n" id="alpha_n"></a>Nicholson on Stromatopora, <a href="#Page_165">165</a>.<br /> -Nummulites, <a href="#Page_73">73</a>.<br /> -Nummuline Wall, <a href="#Page_43">43</a>, <a href="#Page_65">65</a>, <a href="#Page_106">106</a>, <a href="#Page_176">176</a>, <a href="#Page_181">181</a>.<br /> -<br /> -<a name="alpha_o" id="alpha_o"></a>Objections answered, <a href="#Page_169">169</a>, <a href="#Page_188">188</a>.<br /> -<br /> -<a name="alpha_p" id="alpha_p"></a>Parkeria, <a href="#Page_164">164</a>.<br /> -Petite Nation, <a href="#Page_20">20</a>, <a href="#Page_43">43</a>.<br /> -Pole Hill, Specimens from, <a href="#Page_121">121</a>.<br /> -Proper Wall, <a href="#Page_43">43</a>, <a href="#Page_65">65</a>, <a href="#Page_106">106</a>, <a href="#Page_176">176</a>, <a href="#Page_181">181</a>.<br /> -Preservation of Eozoon, <a href="#Page_93">93</a>.<br /> -Protozoa, their Nature, <a href="#Page_59">59</a>, <a href="#Page_207">207</a>.<br /> -Pseudomorphism, <a href="#Page_200">200</a>.<br /> -Pyroxene filling Eozoon, <a href="#Page_108">108</a>.<br /> -<br /> -<a name="alpha_r" id="alpha_r"></a>Red Clay of Pacific, <a href="#Page_222">222</a>.<br /> -Red Chalk, <a href="#Page_222">222</a>.<br /> -Reply to Objections, <a href="#Page_167">167</a>, <a href="#Page_188">188</a>.<br /> -Receptaculites, <a href="#Page_162">162</a>.<br /> -Robb, Mr., referred to, <a href="#Page_120">120</a>.<br /> -Rowney, Prof., Objections of, <a href="#Page_184">184</a>.<br /> -<br /> -<a name="alpha_s" id="alpha_s"></a>Serpentine mineralizing Eozoon, <a href="#Page_102">102</a>.<br /> -<span class="pagenum"><a name="Page_239" id="Page_239">« 239 »</a></span><br /> -Silicates mineralizing Fossils, <a href="#Page_100">100</a>, <a href="#Page_103">103</a>, <a href="#Page_121">121</a>, <a href="#Page_220">220</a>.<br /> -Silurian Fossils infiltrated with Silicates, <a href="#Page_121">121</a>.<br /> -Steinhag, Eozoon of, <a href="#Page_146">146</a>.<br /> -Stromatopora, <a href="#Page_37">37</a>, <a href="#Page_156">156</a>.<br /> -Stromatoporidæ, <a href="#Page_165">165</a>.<br /> -Supplemental Skeleton, <a href="#Page_64">64</a>.<br /> -<br /> -<a name="alpha_t" id="alpha_t"></a>Table of Formations, <a href="#Page_6">6</a>.<br /> -Trinity Cape, <a href="#Page_10">10</a>.<br /> -Tubuli Explained, <a href="#Page_66">66</a>, <a href="#Page_106">106</a>.<br /> -<br /> -<a name="alpha_v" id="alpha_v"></a>Varieties of Eozoon, <a href="#Page_135">135</a>, <a href="#Page_236">236</a>.<br /> -Vennor, Mr., referred to, <a href="#Page_46">46</a>, <a href="#Page_57">57</a>.<br /> -<br /> -<a name="alpha_w" id="alpha_w"></a>Wentworth Specimens, <a href="#Page_91">91</a>.<br /> -Weston, Mr., referred to, <a href="#Page_20">20</a>, <a href="#Page_40">40</a>, <a href="#Page_162">162</a>.<br /> -Wilson, Dr., referred to, <a href="#Page_36">36</a>.<br /> -Worm-burrows in the Laurentian, <a href="#Page_133">133</a>, <a href="#Page_139">139</a>.<br /> -</div> - - -<p class="caption3">Butler & Tanner. The Selwood Printing Works. Frome, and London.</p> - - -<p class="tb_stars">* * * * *</p> - - - -<div class="trans_notes"> - -<p class="caption2">Transcriber Notes</p> - - -<p>The label <a href="#Plate_II">Plate II</a> was added to the illustration’s page. -The “NOTES” sections were -standardized to say “NOTES TO CHAPTER …” and the sections labeled as -(A.), (B.), etc. The small-caps formatting of the first word of the first paragraph for the -CHAPTER VII, NOTE C, was removed to match the other sections.</p> - -<p>The cover image was adapted from an image provided by The Internet Archive and is placed -in the Public Domain.</p> - -</div> - - - - - - - - - -<pre> - - - - - -End of Project Gutenberg's Life's Dawn on Earth, by John William, Sir Dawson - -*** END OF THIS PROJECT GUTENBERG EBOOK LIFE'S DAWN ON EARTH *** - -***** This file should be named 50767-h.htm or 50767-h.zip ***** -This and all associated files of various formats will be found in: - http://www.gutenberg.org/5/0/7/6/50767/ - -Produced by MWS, Tom Cosmas, Bryan Ness and the Online -Distributed Proofreading Team at http://www.pgdp.net (This -file was produced from images generously made available -by The Internet Archive) - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. 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