XI

SOME GENERAL CONCLUSIONS

I

IT may very properly be said that many elements of uncertainty accompany the questions discussed in the previous chapters, and that in any case our information is too scanty to warrant any positive conclusions respecting the origin and earliest history of living beings. On the other hand, it is well to take stock of what we do know, and even of what we may reasonably suppose; keeping always in view the fact that some parts of the problem of the origin of life are at present insoluble, and may possibly ever continue in that condition. I may, therefore, profitably close with a summary of what at present seem to be ultimate facts and principles in this matter, which, if we have not yet fully attained to, we may at least keep in view as objective points.

If we admit that Eozoon was an animal, we may either assume that it was the first introduced on the earth, or that there were earlier and possibly even simpler creatures. In either case we begin the chain of animal life with a Protozoan belonging to one of the simpler or more generalized types of that group, and entitled to the name, both because of its place in order of time and of rank in the development of the animal kingdom. If we deny the claims of Eozoon, then the base of our animal system must for the present be found in the Sponges, Worms, Foraminifera, and Radiolarians of the Huronian, with the problematical laminated forms allied to Cryptozoon which seem to occur even in the Upper Laurentian. Thus in this case the miracle of creation stands before us in a somewhat more complex form, though greatly less so than if we had to accept the fauna of the Lower Cambrian as the oldest known.

Under any supposition we cannot hope to get beyond a Protozoan or a few Protozoa, and we must assume that these could perform perfectly in their simple way those functions of assimilation, organic growth, reproduction, sensation, and spontaneous motion, which are characteristic of these lowest forms of life in the present world.

It is plain, finally, that however simple we imagine this first possessor of animal life to be, we can have no scientific evidence of its origination either as an embryo or as an adult. If it had no living ancestors, we are thus face to face with the problem of the origin of animal life, either by what has been termed "Abiogenesis" of a merely physical and fortuitous kind, or by creation. This implies the previous production of the complex organic compound known as "Protoplasm," which can, so far as we know, be produced only through the agency of previously living "Protoplasm" formed by living plants. We have, therefore, to presuppose the "Abiogenesis" or creation of plants as predecessors of the animal; but here the same difficulty meets us. We have next to imagine the spontaneous origin of the structures of the "Protozoon"—its outer and inner substance, its nucleus, its pulsating vesicle, and its pseudopods, with its protective test, and its endowment with vital powers of locomotion, sensation, assimilation, nutrition, and reproduction. Can we suppose that all this could come of the chance interaction of physical causes?

At present the production of the living from the non-living seems to be an impossibility, and the suggestion that at some vastly distant point of past time physical conditions may have been so different from those at present existing as to permit spontaneous generation is of no scientific value. But if the existence of one primitive Protozoon be granted, what reason have we to believe that it contains potentially the germ of all the succeeding creatures in the great chain of life, and the power of co-ordinating these with the successive physical changes of the geological ages, and so producing the vast and complicated system of the animal kingdom, extending up to the present time? In doing so, we either elevate a low form of animal life into the role of Creator, or fall back on indefinite chance, with infinite probabilities against us. Reason, in short, requires us to believe in a First Cause, self-existent, omnipotent and all-wise, designing from the first a great and homogeneous plan, of which as yet but little has been discovered by us. Thus any rational scheme of development of the earth's population in geological time must be, not an agnostic evolution, but a reverent inquiry into the mode by which it pleased the Creator to proceed in His great work.

Regarding the matter in this way, there is legitimate scope for science in tracing the long lines of the different types of ancient animals to the modern period, and endeavouring to discover which of our so-called species are original types and which are mere derivative varieties or races.

It is evident that nothing is gained here by assuming that the whole geological record is but one of innumerable vast æons of æons, which have gone on in endless succession. If the world is made to stand on an elephant, and this on a tortoise, and this on lower forms, it helps us not at all if the last supporter must stand on nothing. The difficulty thus postponed only becomes greater; and at the end we have to imagine, not only life and organization, but even matter and energy as fortuitously originating or creating themselves, unless produced by an Almighty Eternal Will.

In pursuing studies of this kind, it is best for the present to content ourselves with tracing the continuous chains of similar creatures throughout their extension in geological time, rather than to seek for connecting links between different lines of being. I endeavoured some years ago to give a popular outline of this method in a little work entitled "The Chain of Life in Geological Time."[49]

[49] Religious Tract Society, London; Revell Publishing Co., New York, Chicago, and Toronto.

Taking, for example, the earliest Protozoa—the Foraminifera and Radiolaria—we find two lines of being that in endless varieties, but with little material change, extend from the earliest periods to the present time. In successive ages they are represented by families, genera, and species, which are regarded as distinct, and known by different names. But these humble animals are very variable, and what seem to us to be new types may be merely varieties of ancestral forms. We might even affirm that, for all we know, these two great groups, as they exist in the present ocean, are lineal descendants of those that flourished in the Eozoic. We could not prove this, unless we were to find somewhere a continuous succession of deep-sea deposits that would show the gradual changes that had occurred. On the other hand, it is hard to believe that one individual life, so to speak, could have continued unimpaired to animate successive and increasing masses of matter in all the vast time extending from the Eozoic to the modern. It is also at least equally possible that the causes and conditions, whatever they were, that produced the earliest Protozoa may have acted again and again in later times, originating new lines of descent with renewed vitality.

Still, the tracing of these almost incredibly long lines of descent, if they are such, is a proper, though difficult, subject of scientific research, whatever may be the result. Something has been attempted in this direction over limited portions of time; but a vast amount of patient labour is required before certainty can be attained even in this department of investigation.

When, on the other hand, we turn to the question whether such lines of creation or descent have given off branches leading to new types, as, for instance, from Protozoa to various Crustaceans or Mollusks, we are entirely destitute of facts, and the statement lately made by a leading agnostic evolutionist, that "if there is any truth in the doctrine of evolution, every class of the animal kingdom must be vastly older than the past records of its appearance on the surface of the globe," shows us that all the attempts to construct genealogical trees of the descent of animals are, so far as at present known, quite visionary. It seems, indeed, that each leading line, as we trace it back, ends in a blind alley, just where we might suppose that it was about to pass into another path. This is one reason of the frequent complaints as to the imperfection of the geological record, and of the occurrence of "missing links" between different types of being. The only feasible explanations of this are as yet the suppositions that the times of introduction of new types may have been unfavourable to the preservation of their remains, or that the first representatives of each new group were soft-bodied animals incapable of preservation, or that they happened to be introduced in regions yet unexplored. But such accidents could scarcely have been the rule in every case. Even in relation to man himself, he is still man in all the deposits in which we can find his remains, and as remote from the apes of his time, in so far as we know, as he is from those now his contemporaries. It would seem, in short, as if, ashamed of his humble origin, he had carefully obliterated his tracks in ascending from his lowly parentage to the dignity of humanity. But in this he is only following the example of other animals, his predecessors. We may, as is now constantly done by evolutionists, fill up these gaps by plausible conjectures; but this is not a scientific mode of procedure, unless we are content to regard these conjectures as working hypotheses in aid of researches yet without result.

It is important that general truths of this kind, impressed upon us by our descent to the ascertained beginnings of life, should be generally known, as counteractive to the confident statements so frequently put forth by enthusiastic speculators and caterers of sensational popular science. In point of fact, we still occupy the position so long ago defined by the Apostle Paul, that "God's invisible things from the creation of the world are clearly seen, being understood by the things that are made, even His eternal power and divinity"; and the rational student of nature must still be a pupil in the school of the Almighty Maker of all things.

Realizing this, we can learn something both as to the dignity and the humility of our own position. On the one hand we perceive that, in the whole chain of life, man is the only being in the likeness of the Maker, fitted to be His deputy in the world, to understand His great work, and to be the heir of the whole. To man alone He has proclaimed, "I have said ye are gods, and all of you children of the Most High." To man alone has He given that "inspiration of the Almighty" which makes Him the interpreter of nature. On the other hand, when we consider the long extent in time of the great chain of life before man, and along with this the vast oceanic area inaccessible to us, yet ever since the dawn of life teeming with living things innumerable, we find that man is not even in this little world the only object of Divine care, and we learn a lesson of humility and of the obligations which rest on us not only in relation to our fellow-men, but toward our humbler companions who share with us the care of their Father and ours.

Finally, it is plain that scientific investigation can never bring us within reach of the absolute origin of life, otherwise than by the action of a creative Will. Had we stood on the earliest shore, and had we seen living things appear in the waters where before had been merely inorganic sand or rock, we should have known as little as we know to-day of even the proximate causes of this new departure in nature. If agnostics, we might have said, "this is spontaneous generation"; but such an expression would convey no distinct idea of the nature of the change which had occurred. It would be merely a cloak for our ignorance. If theists, we might say, "this is creation"; but we would have heard no audible fiat, nor seen any process or manipulation, nor known by what subordinate agency, if any, the result was produced. We could have given no further explanation than that of the ancient writer who tells us that God said, "Let the waters swarm with swarmers." We are told that when these great creative changes occurred, they were witnessed by higher intelligences than man. "Then the morning stars sang together, and all the sons of God shouted for joy"[50]; but even they could perhaps know little more than we, though they might be better able to trace the future development of the wonderful plan commenced in the humble Protozoa and culminating in man and immortality.

[50] Job xxxviii. 7.

APPENDIX

APPENDIX

A. Geological Relations of Eozoon, Archæozoon, etc.

I

IN the text I have given the arrangement of the pre-Cambrian rock-formations of Canada, as understood by me at the time of the delivery of the lectures on which this work is based—an arrangement which I believe will, in the main, be sustained by the work of the future, but which cannot as yet be received as final. The work of Logan and Murray, so far as I have had opportunity to go over their ground, was admirable; but since their time the progress in the settlement of the country, the extension of railways, and other means of communication, and the opening up of mineral deposits have greatly increased the means of obtaining information, and detailed explorations have been in progress under the Geological Survey of Canada. At this moment, under the new Director of the Survey, Dr. G. M. Dawson, much work is being done in this difficult field, more especially by Dr. Ells, Dr. Adams, and Mr. Barlow, which it may be hoped will go far to settle finally the arrangement and distribution of pre-Cambrian rocks in the Northern part of the American Continent. The maps and detailed reports representing these explorations are not yet before the public, but from some preliminary notices which have appeared in scientific periodicals, it may be inferred that the distinction between the fundamental gneiss, with its associated igneous products, and the Upper Laurentian, will become greater than was supposed by Logan. The Lowest Laurentian or Trembling Mountain series of Logan now represents a very widely extended basement formation, not so far as can be ascertained, composed of sedimentary rocks in a metamorphosed state, but rather of peculiar aqueo-igneous materials, different from the greater part of those which succeeded them, and associated with varied and extensive igneous intrusions and in-meltings like those which Keilhau ascertained long ago in the case of similar rocks in Norway. The Grenville series, on the other hand, may prove to be a remnant of an overlying system, originally less extensive or bordering the older group, and greatly attenuated by the enormous denudation which the whole region has undergone.

Fig. 60.—Eozoon Canadense.
Portion of a large specimen. Nature-printed. Showing the laminæ, and irregular cavities filled with serpentine, perhaps corresponding to the funnels.

[To face p. 296.

It may also be found that the beds of limestone are fewer and their repetitions more numerous than had been supposed, and that the Grenville series may be closely associated locally, at least, with beds hitherto of uncertain age, or associated with the Lower Huronian. The Huronian proper, on the other hand, may be considerably extended, and the Kewenian and Animiké series overlying it have already been ascertained by the Canadian Geological Survey to overlap the Huronian and Laurentian over vast areas between the great lakes and the Arctic sea, evidencing much submergence at the close of the Huronian age, and opening of the Palæozoic. I have noticed in the text the apparently wide development of deposits of this age over the area of the Rocky Mountains of Canada, and the corresponding territories in the United States. There would seem to be in these regions a great thickness of unaltered sediments between the Lower Cambrian and the crystalline rocks below, representing the Huronian and Laurentian. In these very few fossils have yet been found, but they afford perhaps the most promising field, next to their representatives in Newfoundland and New Brunswick, for the discovery of the predecessors of the Olenellus fauna, and the forms of life connecting these with those known in the Huronian and Laurentian. [For summaries of facts on the last-mentioned subject, see Report of Dr. G. M. Dawson on the Kamloops map-sheet, in "Reports of Geological Survey of Canada," vol. vii. B, new series, pp. 29 et seq.; also Reports of Dr. C. D. Walcott, U. S. Geological Survey, vol. xiv., Part I., pp. 103 et seq., and Part II., pp. 503 et seq.]

B. Preservation of Organic Remains by Injection with Hydrous Silicates.

The late Dr. T. Sterry Hunt contributed to the original paper on Eozoon in the Journal of the Geological Society, a valuable essay on the mineralization of fossils by serpentine, glauconite, and allied hydrous silicates. This was in part reprinted in the notes appended to one of the chapters of "The Dawn of Life," and the subject was further discussed by Hunt in his invaluable work, "Chemical and Geological Essays," and more especially in the chapter on the "Origin of Crystalline Rocks," a chapter which every geologist deserving the name should study with care.

I give here some of the more important facts referred to by Hunt, and may add that subsequent microscopic studies have familiarized me with the occurrence of serpentine and other hydrous silicates as fillings of the cavities of fossils of various geological ages, insomuch that I have come to regard the occurrence of these rocks in association with fossiliferous limestones as among the best available means to enable us to ascertain the minute structures of shells, Foraminifera, corals, etc.

The following remarks and analyses further illustrate Hunt's views on the relations of these minerals, with some of the facts on which they are based:—

"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 grassier, 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.
Silica40·048·535·1446·5850·7050·7
Protoxyd of iron24·722·08·6020·6122·508·6
Magnesia16·63·831·471·272·163·7
Lime3·32·491·11
Alumina1·717·010·1511·458·0319·8
Potashtraces6·965·808·2
Soda·98·75·5
Water12·67·014·649·668·958·5
—————————-—————-
98·998·3100·00100·00100·00100·0

An eminent example is the Silurian limestone of Pole Hill, in New Brunswick, collected by the late Mr. Robb, of the Geological Survey, and referred to in the text. I cannot doubt that the silicate injecting Crinoids and other fossils in this limestone must have been introduced into these when still recent, and the same remark applies to the serpentine filling a coral at Lake Chebogamong, and fragments of corals at Melbourne, in Eastern Canada, and to the similar mineral filling fossils in a limestone from Llangwyllog, in Wales, and in that of Maxville, Ohio. Hunt regarded all these as coming essentially into the same category as regard to general composition and properties. His analysis of the minerals from Pole Hill and Llangwyllog is as follows:—

Pole Hill.Llangwyllog.
Silica38·9335·32
Alumina28·8822·66
Protoxyd of iron18·86

24·12

Magnesia4·256·96
Potash1·691·40
Soda·480·67
Water6·9111·46
Insoluble, quartz
——————
100·0099·89

These minerals approach in composition to the jollyte of Von Kobell, from which they differ in containing a portion of alkalies, and only one half as much water. In these respects they agree 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;[51] the Eozoon itself being there injected with a hydrous silicate which may be described as intermediate between glauconite and chlorite in composition."

[51] Journ. fur Prakt. Chemie, Bd., 106 (1869), p. 356.

In the Welsh specimen the silicate is of a deep green colour, except where oxidized, and though only 3 per cent, of the whole, is sufficient to give it an olive colour and slight serpentinous lustre. In the Pole Hill material, the silicate amounts to 5 per cent, of the whole, and is of a greyish colour. For some further particulars, see my Paper on "Fossils Mineralized with Silicates" (Journal Geological Society, February, 1879).

C. Affinities of Eozoon, etc., with more Modern Forms.

Dr. Carpenter, who in admirable papers, which I need not quote here,[52] has illustrated in detail the structures of Eozoon, and shown its resemblance to modern forms, places Eozoon as a generalized type between the Nummuline and Rotaline groups of Foraminifera. It resembles the former in its fine and complicated tubulations, and some of the larger sessile forms of the latter in its habit of growth. More especially, this is near to that of the genera Carpenteria and Polytrema. In the former, more especially, there are a number of somewhat flattened calcareous cells with perforated walls, and built up in a conical form around a central pipe or funnel into which the apertures of the cells open. A specimen of Carpenteria, enlarged and having the walls of its cells thickened by a supplemental tubulated deposit like that of Calcarina, would approach very near to Eozoon.

[52] I may specially refer to the following:—

W. B. Carpenter on Eozoon Canadense. Intellectual Observer, No. xl., p. 300, 1865. Supplemental notes on the structure and affinities of Eozoon Canadense, Quart. Journ. Geol. Soc., Lond. Vol. xxii., pp. 219-228, 1866. Notes on the structures and affinities of Eozoon Canadense. Canad. Nat., new ser., vol. ii., pp. 111-119, wood-cut, 1865. A reprint from Quart. Journ. Geol. Soc., Lond., 1865. Further observations on the structure and affinities of Eozoon Canadense. In a letter to the President. Proc. Roy. Soc., Lond., vol, xxv., pp. 503-508, 1867. New observations on Eozoon Canadense. Ann. and Mag. Nat. Hist., sen 4, vol. xiii., pp. 456-470, one plate, 1874. Final note on Eozoon Canadense. Ann. and Mag. Nat. Hist., ser. 4, vol. xiv., pp. 371-372, 1874. Remarks on Mr. H. J. Carter's letter to Prof. King on the structure of the so-called Eozoon Canadense. Ann. and Mag. Nat. Hist., ser. 4, vol. xiii., pp. 277-284, with two engravings, 1874.

The question of the general relation of an organism like Eozoon to creatures known to us in the modern seas may be answered in either of two ways:—(1) Functionally or in relation to the position of such an animal in nature: or (2) Zoologically, or with reference to its affinities to other animals. With reference to the first consideration, the answer is plain. The geological function of Eozoon was that of a collector of calcareous matter from the surrounding waters, then probably very rich in calcium carbonate, and its role was the same with that of the Stromatoporæ and calcareous Sponges, smaller Foraminifera and Corals in latter times. The answer to the second aspect of the question is less easy. An ordinary observer would at once place Eozoon with the Stromatoporidæ or Layer-corals, which fill or even constitute whole beds of limestone in the Cambro-Silurian, Silurian and Devonian Periods. While, however, Eozoon has been claimed on the highest authority for the Rhizopods, the Stromatoporæ and their allies have been regarded as Sponges, or more recently as Hydroids allied to the Hydractiniæ and Millepores.[53] I confess that I am not satisfied with these interpretations. I have in my collections large numbers of encrusting spinous forms, usually called Stromatoporæ, but which I have long set aside as probably Hydractiniæ. There are other forms with large vertical tubes which I have regarded as corals, but some Stromatoporæ seem to be different from either, and I am still disposed to regard many of them as Protozoa. Bearing in mind, however, that the Silurian is as remote from the Laurentian on the one hand as from the Tertiary on the other, we might be prepared to expect that if the Layer-corals of the Silurian are divisible into different groups, somewhat widely separated, and we have in the lower Palæozoic the peculiar type of Cryptozoon, we may be prepared to expect in the Laurentian much more generalized forms, less susceptible of classification in our modern systems. If, therefore, Eozoon were accessible to us in a living state, I should not be surprised to find that—while perhaps more akin to the calcareous-shelled Rhizopods than to any other modern group—it may have presented points of resemblance to Sponges or even to Hydroids, in its skeleton and mode of growth, and even in the arrangement of its soft parts.

[53] See Nicholson and Murie's able memoirs, Publications of Pal. Soc, 1885.

Taking this view of its nature and relations, the genus and the Laurentian species may be characterized as follows:—

Genus Eozoon, Dawson.

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 inverted conical or 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 branching 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 Upper 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.

Assuming the Archæospherinæ so abundantly found in the Eozoon limestones to be distinct organisms, and not mere germs or buds of Eozoon, they may be thus defined:—

Genus Archæospherina, Dawson.

A provisional genus, to include rounded solitary chambers, or globigerine assemblages of such chambers, with the cell-wall surrounding them tubulated as in Eozoon, or perhaps in some cases with simple pores like those of Rotalines. 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 limestones at Côte St. Pierre. Age Upper Laurentian.

I may add here the characters of Matthew's new genus, Archæozoon, as given by him:—

Genus Archæospherina, Matthew.

Skeleton composed of thin concentric laminæ convex upward, and having between them a granular layer filled with minute branching canals.

Archæospherina Acadiense, Matthew.

Habit of growth cylindrical in masses or groups, budding upward. The microscopic characters are thus given by Matthew[54]:—

"The structures appear to be allied more closely to Cryptozoon than to Eozoon. The microscopic structure is most easily recognised in the earthy (as distinguished from the calcareous) layers, and consists of minute branching canals. Under a one-inch objective the smaller canals have the appearance of minute threads, which run sometimes for a distance of two millimetres without branching. The larger canals branch more frequently and are more sinuous. The canals cross and anastomose with each other; they run chiefly at right angles to the axis of the fossil, and appear to branch most in going outward from the centre. More rarely they ascend from the earthy to the calcareous layer, branching upward."

[54] Bulletin No. ix., Nat. Hist. Soc of New Brunswick, 1890.

In limestone of the Upper Laurentian, near St. John, New Brunswick.

D. Cryptozoon.

The description above given of Archæozoon very naturally leads us to consider the allied Cambrian and pre-Cambrian forms known as Cryptozoon.

This remarkable and problematical type was first described by Prof. James Hall in the Appendix to his Annual Report of 1882 (No. 26). It is a large massive organism, occurring abundantly on the surface of a limestone of Calciferous (Upper Cambrian) age at Greenfield, Saratoga County, New York. The individuals sometimes attain a diameter of two feet, and are often surrounded by smaller specimens apparently budding off from them. Like Stromatoporæ, they consist of concentric laminæ, but these are concave upward, giving a bowl-shaped form to the summits of the individuals. Prof Hall describes them as "made up of irregular concentric laminæ of greater or less density, and of very unequal thickness. The substance between the concentric lines in well-preserved specimens is traversed by numerous minute irregular canaliculi which branch and anastomose without regularity. The central portion of the masses is usually filled with crystalline granular and Oolitic material, and many specimens show the intrusion of these extraneous and inorganic substances between the laminæ."

Professor Hall having kindly presented some good specimens to the Peter Redpath Museum, I have had sections made, and have thus been able to verify his description, and to compare the structures with those of some of the more ancient Stromatoporoid specimens in our collections, including the Archæozoon from New Brunswick, of which Mr. Matthew has presented a fine slab to the Museum. I have also, through the kindness of Professor Winchell, been enabled to compare these with his Cryptozoon Minnesotense, and Dr. Walcott has added specimens of his Stromatoporoid forms from the pre-Cambrian beds of Arizona. It would appear from these and other specimens in our collections from the Cambrian and older Ordovician beds, that we have here an ancient type of Stromatoporoid organism in which the original laminæ seem to have been thin and coriaceous, without apparent pores or pillars connecting them with each other, but having between them relatively-thick layers of fine fragmental matter penetrated by numerous irregularly tortuous and branching tubes. The laminæ often present a carbonaceous or chitinous appearance, though frequently replaced by mineral matter, and the intervening layers show both a calcareous and carbonaceous substance, with much fine silicious sand often as rounded grains, and apparently some dolomitic granules. The tubules seem destitute of any distinct wall, otherwise the whole would resemble on a large scale the nodular and laminated masses of Girvanella, which Wethered has described as surrounding organic fragments in Silurian and Carboniferous and Jurassic limestones in England.[55]

[55] British Association, Liverpool meeting, 1896.

The Streptochetus of Seely from the Chazy limestone[56] is evidently very near to Girvanella, if not generically identical, and I have a similar species from the Lower Cambrian pebbles in the conglomerates of the Quebec group. In all these forms, however, the thicker or intermediate laminæ seem to consist wholly of definite convoluted tubes, whereas in Cryptozoon the tubes, or tubular perforations, are separated by a mass of material which in the best preserved specimens seems to consist of a fibrous stroma including calcareous and silicious particles. It seems doubtful to what class of beings such a structure should be referred; but whatever its nature, it evidently had great powers of growth, and seems to be a very ancient form of life.

[56] Amer. Journ. of Science, 1885. See Nicholson, "Manual of Palæontology," ed. of 1889.

One of the species similar in structure to Hall's type, but budding out into turbinate branches, was discovered by Mr. E. T. Chambers, of Montreal, in the Ordovician limestone of Lake St. John, and has been named C. boreale. It differs in structure from Hall's species in having the tubes less tortuous and more nearly parallel to the laminæ. In its outline it reminds one of the problematical Eozoon from the Hastings group at Tudor, Ontario, referred to in the text.

Should time permit, I hope to have all the specimens in our collections illustrating this interesting and primitive type examined and described. In the meantime I may merely remark that a near modern analogue would seem to be the gigantic arenaceous Foraminifer Neusina Agassizi, Goës, dredged by Alexander Agassiz in the Pacific, and described in the Bulletin of the Museum of Comparative Zoology (Vol. xxiii., No. 5, 1892). The modern form, it is true, is flat and foliaceous; but some of the old species approach to this shape, and if we suppose the little cells of Neusina to represent the tubes of Cryptozoon, and the carbonaceous matter of the latter to be the remains of the chitinous stroma seen in some specimens, the general resemblance will be very close.

The whole subject of these peculiar Stromatoporoid forms extending from the Upper Cambrian to the Laurentian, deserves a full and careful investigation, for which I am endeavouring to collect material.

E. Receptaculites and Archæocyathus.

In "The Dawn of Life" (1875), reference was made to the singular and complicated organisms of the Upper Cambrian and Ordovician systems known as Receptaculites, which at that time was generally regarded as foraminiferal, and is still placed by Zittel, in his great work on Palæontology, among forms doubtfully referable to that group. It has also been referred to Sponges, though on very uncertain grounds. It has not, however, so far as I am informed, been traced any farther back than the Upper Cambrian (Calciferous), and no structural links are known to connect it with either Eozoon or Archæozoon. For this reason it was omitted in the text; but I think it well to mention it here, and to direct attention to it as possibly one of the complex Protozoa which may be traced far back toward the beginnings of life.[57]

[57] Billings, "Palæozoic Times."

Another primitive and generalized genus mentioned in the text is Archæocyathus of Billings, whose headquarters seem to be in the Lower Cambrian, and which may probably be traced farther back.

Mr. Billings described the genus in his "Report on Canadian Fossils" (1861-64), taking A. profundus, from the Lower Cambrian of L'Anse à Loup, on the Labrador coast, in the first instance, as the type.

A few years later, my attention was attracted to this species by specimens presented to me by Mr. Carpenter, a missionary on the Labrador coast, and which Mr. Billings kindly permitted me to compare with his specimens in the Museum of the Geological Survey, collected by the late Mr. Richardson, at L'Anse à Loup, in Labrador, in what were then called Lower Potsdam rocks. Slices of the specimens were made for the microscope, when it appeared that, though they had the general aspect of turbinate corals, like Petraia, etc., they were quite dissimilar in structure, more especially in their porous outer and inner walls and septa (see [Fig. 5, p. 35]). Yet they could scarcely be referred to the group of porous corals known in much later formations and in the modern seas. Nor could they be referred with much probability to Sponges, as they were composed of solid calcareous plates, which, as was evident from their textures, could not have been originally spicular. One seemed thus shut up to the conclusion that their nearest alliance was with Foraminifera, and if so, they were very large and complex forms of that group, consisting of perforated chambers arranged around a central cavity. I accordingly mentioned them in this connection in 1875, not as closely related to Eozoon, but as apparently showing the existence of very complex foraminiferal forms in the Lower Cambrian.

The specimens thus noticed were altogether calcareous, and were of the species named A. profundus by Mr. Billings. He had, however, referred to the same genus silicified specimens from a later formation, the Calciferous (Upper Cambrian) at Mingan, under the name A. Minganensis, which were subsequently found to be associated with spicules resembling those of lithistid sponges, and which proved to be very different from the Lower Cambrian form, and are now referred to a different genus. The subject had thus become involved in some confusion, and was left in this state by Mr. Billings on his death. I therefore asked my friend, Dr. Hinde, of London, to re-examine my specimens, and at the same time those of the Geological Survey were placed in his hands by Mr. Whiteaves. Hinde also obtained specimens from Lower Cambrian rocks in Sardinia, where they seem to be abundant, and from Spain. He states the results of his examinations very fully in a paper in the Journal of the Geological Society of London.[58] He retains the original name for the older and calcareous form from L'Anse à Loup, separating from it, however, another form, A. Atlanticus of Billings's, which is destitute of distinct radiating septa and acervuline, like the lower part of A. profundus. This he names Spirocyathus. The Mingan species he places with Sponges under the generic name, Archæoscyphia. In this Walcott substantially agrees with Hinde in his "Memoir on the Lower Cambrian Fauna." Both seem to refer Archæocyathus to corals, though admitting its very exceptional and anomalous structure. I think, however, we may still be allowed to entertain some doubts as to the reference to corals, more especially as the skeleton does not seem to have consisted of aragonite, but of ordinary calcite, like that of the Foraminifera. It is in any case a primitive form which seems to be dying out in the Lower Cambrian, and we may hope that it may be traced into the pre-Cambrian, and may form a link connecting the Palæozoic with the Eozoic faunas. In my description of it in "The Dawn of Life" in 1875, I used the following terms:—"To understand Archæocyathus, let us imagine an inverted cone of carbonate of lime from an inch or two to a foot in length, with its point planted in the mud in the bottom of the sea, while its open cup extends upward into the clear water. The lower part buried in the bottom is composed of an irregular network of thick calcareous plates, enclosing chambers communicating with one another. Above this, where the cup expands, its walls are made up of inner and outer plates, perforated with numerous round pores in vertical rows, and connected with each other by vertical partitions also perforated, so as to establish a free communication of the enclosed radiating chambers with each other, as well as with the water within and without. Such a structure might no doubt serve as a skeleton for a coral of somewhat peculiar internal structure, but it might just as well accommodate a protozoan with chambers for its sarcode, and pores for emission of pseudopods, both outwardly and by means of the interior cup, which in that case would represent a funnel like that of Carpenteria, or one of the tubes of Eozoon."

[58] Vol. xlv., 1889, pp. 125 et seq.

On the whole, when we consider the magnitude and synthetic character of such forms as Cryptozoon, Receptaculites, and Archæocyathus, and their association with generalized types of Crustaceans and Brachiopods, we can scarcely fail to perceive that at the base of the Palæozoic we are leaving the reign of the higher marine invertebrates, and entering on a domain where lower and probably Protozoan forms must be dominant, and so are getting at least within calculable distance of the beginnings of life.

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.

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,[59] 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.

[59] Nature, March 17, 1892.

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.

[In my subsequent notice of the Tudor specimens in "The Dawn of Life," in 1875, I referred to their age as "Upper Laurentian or Huronian"; and I may add, that while it is certain that the beds containing them are pre-Palæozoic, their place in the Eozoic period is still not precisely determined. Work is, however, now in progress which it is hoped may finally settle the age of the "Hastings group" and the old rocks associated with it. I may add that the specimen of Cryptozoon discovered by Mr. Chambers, and of which a portion is represented in the Frontispiece, seems to me to throw a new light on the Tudor specimen. It shows in any case the survival of Cryptozoa similar in form and general appearance to that specimen, as late as the Cambro-Silurian or Ordovician.]

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.