Part 18

F. Pre-Geological Evolution.

Reference is incidentally made in the text to the doctrine implied in the old notion of successive cataclysms and renewals of the earth, held by some ancient mythologies and philosophies, and revived in a slightly different form by Mr. Herbert Spencer, in connection with the requirements of the Darwinian evolution by natural selection. This primitive idea was illustrated at considerable length by Professor Poulton in his address as President of the Zoological Section of the British Association at its meeting in Liverpool (September, 1896). In this new and ably presented form, it deserves some notice as excluding the hope of our finding the beginnings of life in any geological formations at present known.

Professor Poulton refers to the argument used by Lord Salisbury, in his address at the Oxford meeting, on the insufficiency of time for the requirements of the Darwinian evolution. He then discusses the estimates based by Lord Kelvin and Professor Tait on physical considerations, and dismisses them as altogether inadequate, though he admits that Professor George Darwin agrees with Lord Kelvin in regarding 500 millions of years as the maximum duration of the life of the sun.

He next takes up the estimates of geologists, and rather blames as too modest those who ask for the longest time, say 400 millions of years, for the duration of the habitable earth. He evidently scarcely deems worthy of notice the more moderate demands of many eminent students of the earth, who have based far lower estimates on more or less reliable data of denudation and deposition, and on the thickness of deposits in connection with their probable geographical extent.

He then proceeds to consider the biological evidence, and dwells on the number of distinct types represented as far back as the Lower Cambrian. Independently of the interpretations and explanations of this great fact, the numerous types there represented, and the persistence of some of them to the present day, give an almost overwhelming impression of the vast duration of organisms in time. In connection with the supposed slow and gradual process of evolution, this naturally leads to the conclusion that "the whole period in which the fossiliferous rocks were laid down must be multiplied several times for this later history (that of the higher groups of animals alone). The period thus obtained requires to be again increased, and perhaps doubled for the earlier history." Ordinary geologists naturally stand aghast at such demands, and inquire if they are seriously put forth, and if it would not be wise to hesitate before accepting a theory on behalf of which such drafts on time must be made. The late Edward Forbes once humorously defined a geologist to be "an amiable enthusiast who is happy and content if you will give him any quantity of that which other men least value, namely, past time." But had this great naturalist lived to "post-Darwinian" times, he might have defined a Darwinian biologist to be an insatiable enthusiast, who feels himself aggrieved if not supplied with infinity itself, wherein to carry on the processes of his science. Seriously however, the necessity for indefinitely protracted time does not arise from the facts, but from the attempt to explain the facts without any adequate cause, and to appeal to an infinite series of chance interactions apart from a designed plan, and without regard to the consideration, that we know of no way in which, with any conceivable amount of time, the first living and organized beings could be spontaneously produced from dead matter. It is this last difficulty which really blocks the way, and leads to the wish to protract indefinitely an imaginary process, which must end at last in an insuperable difficulty.

Were Evolutionists content to require a reasonable time for the development of life, and to assign this to an adequate cause, they might see in the reduction of living things in the pre-Cambrian ages to few and generalized or synthetic types, evidence of an actual approach to the beginnings of life, and beyond this to a condition of the earth in which life would be impossible.

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G. Controversies Respecting Eozoon.

In the text (Chapter IX.) I have referred in a cursory manner to these, but have felt that it would be unprofitable to fight the old battles over again, except in so far as the objections raised have suggested new lines of study and investigation. The old objections of Messrs. Rowney, King and Carter were conclusively replied to by the late Dr. Carpenter. The later criticisms of Möbius in his elaborated memoir in "Palæontographica" were in appearance more formidable; but he had evidently entered on the question with imperfect material, and a very defective conception of its extent and meaning. His treatment of it was also marked by unfairness to those who had previously worked at the subject, and by that narrow specialism and captious spirit for which German naturalists are too deservedly celebrated. The difficulties he raised were met at the time, more especially in articles by the present writer in the American Journal of Science, and in the Canadian Naturalist. Möbius, I have no doubt, did his best from his special and limited point of view; but it was a crime which science should not readily pardon or forget, on the part of editors of the German periodical, to publish and illustrate as scientific material a paper which was so very far from being either fair or adequate.

The later objections of Gregory and Lavis are open to similar criticism as imperfect and partial, and as confounding Eozoon with mineral structures which previous writers had carefully distinguished from it. I have stated these points in letters to Nature and to the Council of the Dublin Academy, and have also re-stated the evidence bearing on the animal nature of Eozoon in a series of papers in the Geological Magazine for 1895. I may add here, as apposite to the present condition of the matter, a few remarks referring to the appearance of Eozoon in Dr. Dallinger's new edition of Carpenter's great work on the Microscope, and more especially to his retaining unchanged the description of Eozoon Canadense, as a monument of an important research up to a certain date, while adding a note with reference to the later criticisms of Mr. Gregory.

Dr. Carpenter devoted much time to the study of Eozoon, and brought to bear on it his great experience of foraminiferal forms, and his wonderful powers of manipulating and unravelling difficult structures. After having spent years in studying microscopic slices of Eozoon and the limestones in which it occurs, I have ever felt new astonishment when I saw the manner in which, by various processes of slicing and etching, and by dexterous management of light, he could bring out the structure of specimens often very imperfect. Not long before Dr. Carpenter's death, I had an opportunity to appreciate this in spending a few days with him in studying his more recently acquired specimens, some of them from my own collections, and discussing the new points which they exhibited, and which unhappily he did not live to publish. Some of these new facts, in so far as they related to specimens in our cabinet here, have since that time been noticed in my résumé of the question in the "Memoirs of the Peter Redpath Museum," 1888.

Those who know Dr. Carpenter's powers of investigation will not be astonished that later observers, without his previous preparation and rare insight, and often with only few and imperfect specimens, should have failed to appreciate his results. One is rather surprised that some of them have ventured to state with so great confidence their own negative conclusions in a matter of so much difficulty, and requiring so much knowledge of organic structures in various states of mineralization. For myself, after working fifty years at the microscopic examination of fossils and organic rocks, I feel more strongly than ever the uncertainties and liabilities to error which beset such inquiries.

As an illustration in the case of Eozoon: since the publication of my memoir of 1888, which I had intended to be final and exhaustive as to the main points in so far as I am concerned, I have had occasion to have prepared and to examine about 200 slices of Eozoon from new material; and while most of these have either failed to show the minute structures or have presented nothing new, a few have exhibited certain parts in altogether unexpected perfection, and have shown a prevalence of injection of the canal system by dolomite not previously suspected. I have also observed that unsuitable modes of preparation, notably some of those employed in the preparation of ordinary petrological slices, may fail to disclose organic structures in crystalline limestones when actually present. Since that publication also, the discoveries of Mr. Matthew in the Laurentian of New Brunswick, and the further study of the singular Cambrian forms of the type of Cryptozoon, have opened up new fields of inquiry.

I think it proper to state, in reference to Dr. Dallinger's footnote on the recent paper of Mr. Gregory, that it must not be inferred from it that Mr. Gregory had access to my specimens from Madoc and Tudor, though he no doubt had excellent material from the collections of the Canadian Geological Survey. It might also be inferred from this note that I have regarded the Madoc and Tudor specimens as "Lower Laurentian." The fact is, that I was originally induced in 1865, by the belief of Sir W. E. Logan at that time that these rocks were representatives in a less altered state of the middle part of the Laurentian, to spend some time at Madoc and its vicinity in searching for fossils, but discovered only worm-burrows, spicules, and fragments of Eozoon, which were noticed in the Journal of the Geological Society for 1866. (The more complete specimen from Tudor was found by Vennor in 1866.) On that occasion I satisfied myself fully that the beds are much older than the Cambro-Silurian strata resting on them, unconformably; but I felt disposed to regard them as more probably of the age of some parts of the Huronian of Georgian Bay, which I had explored with a similar purpose under Logan's guidance in 1856.

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H. Notes to Appendix, December, 1896.

While this work was going through the press, I have received the Report of the U.S. Geological Survey for 1894-95, containing the elaborate Memoir of C. R. Van Hise on the pre-Cambrian Geology of North America. It is a very valuable contribution to the literature of this difficult subject, and will constitute a standard book of reference: though I think the use of the term "Algonkian" for groups of beds which are in part basal Palæozoic and in part Eozoic or Archæan is to be deprecated, and scarcely sufficient importance is attached to the labours of the early Canadian explorers in this field.

In the past summer I was enabled to spend a few days, with the assistance of my friend Mr. H. Tweeddale Atkin, of Egerton Park, Rock Ferry, in examining the supposed pre-Cambrian rocks of Holyhead Island and Anglesey. Fossils are very rare in these beds. As Sir A. Geikie has shown, the quartzite of Holyhead is in some places perforated with cylindrical worm-burrows, and in the micaceous shales there are long cylindrical cords, which may be algæ of the genus Palæochorda, and also bifurcating fronds resembling Chondrites; but I saw no animal fossils. I have so far been unable to discover organic structure in the layers of limestone associated with apparently bedded serpentine in the southern part of Holyhead Island. In central Anglesey there are lenticular beds of limestone and dolomite associated with pre-Cambrian rocks, which Dr. Callaway regards as probably equivalent to the Pebidian of Hicks. In these there are obscure traces of organic fragments; and in one bed near Bodwrog Church I found a rounded laminated body, which may be an imperfectly preserved specimen of Cryptozoon, or some allied organism. The specimens collected have not, however, been yet thoroughly examined. These and other pre-Cambrian deposits in Great Britain correspond in their testimony, with the Eozoic rocks of North America, as to the small number and rarity of fossil remains in the formations below the base of the Palæozoic, and the consequent probability that in these formations we are approaching to the beginning of life on our planet; though there is still reason to hope that additional oases of life may be found in these deserts of the pre-Palæozoic. Such rare intervals of fertility should be the more valued when the labours of so many skilled observers have proved so meagre in their results in comparison with the great extent and thickness of the beds which have been explored.

INDEX

PAGE

Adams on composition of Laurentian schists 108 ---- his work on Laurentian stratigraphy 296 Animals, Cambrian, classes of 7, 11 ---- pre-Cambrian 53 ---- Huronian 67 ---- Grenvillian 73, 303 Antiquity, relative 6 Aquatic animals, permanence of 13 Aragonite in fossils 117 Archæocyathus 35, 315 Archæozoon 214, 309

Barlow, his explorations 296 Bavaria, Eozoon of 71 Beecher on limbs of Trilobites 25 Bicknell on Eozoon 141 Billings on Eozoon 137 ---- on Receptaculites 315 ---- on Archæocyathus 316 ---- on Signal Hill fossils 54 Bonney on Côte St. Pierre 142 Burbank on Chelmsford Eozoon 141

Calcarina 186 Calumet, Grand, Eozoon of 130 Canals of Eozoon 133 Cambrian, life of Early 17 ---- geography of the 18 Carbon in Laurentian limestone 93 Carpenter, Dr., on Eozoon 137, 303, 324 Cayeux on Huronian fossils 68 Chambers, Mr. E. T. 313 Chrysotile, veins of 161, 239 Cœnostroma 174 Colorado cañon 56 Controversies respecting Eozoon 324 Corals, history of 32 Côte St. Pierre 88, 91 Cryptozoon 36, 56, 310

Dallinger, note on Eozoon 325 Dawson, Dr. G. M. 66, 295

Ells, Dr. 217, 296 Eozoon, its discovery 73, 125 ---- its general form 149 ---- its mode of occurrence 90 ---- its state of preservation 111 ---- its laminæ and chambers 152, 157 ---- its canals and tubuli 133, 138, 158, 160 ---- its funnels 152 ---- its minute granular structure 133 ---- its characters and affinities 307 ---- objections to its animal nature 221 ---- acervuline specimens 203 ---- in various places 141, 233 ---- Bavarian species 71, 213 ---- Tudor specimens 68 ---- fragments of, in limestones 183 Eozoon, restoration of 327 Eozoic time as a geological age 76 Etcheminian system 48 ---- fossils of 54 Evolution, pre-geological 320

Foraminifera, notice of modern 175 ---- Etcheminian 59 ---- Huronian 71 ---- Laurentian, etc. 303 Fossils, how mineralized 111

Glauconite, mineralizing fossils 217, 298 Granular structure in Eozoon 165 Graphite of the Laurentian 93 Gregory on Eozoon 235, 325 Grenvillian series 39 Gresley on Huronian worms 68 Gümbel on European Eozoon 71, 213

Hall, Dr. James, on Cryptozoon 36, 310 Hanford Brook, section at 51 Hastings series (Huronian ?) 67 Hinde on Archæocyathus 34, 317 Hunt, Dr. Sterry, on indications of life 97 ---- on silicates in fossils 298 Huronian system 65 Hymenocaris 27