Eozoon

“ It is only by a somewhat wild poetical licence that Eozoon has been represented as a "kind of enormous composite animal stretching from the shores of Labrador to Lake Superior, and thence northward and southward to an unknown distance, and forming masses 1,500 feet in depth." We may 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 - 184 - higher grade can attain. ”

“ 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 - 307 - 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. ”

“ 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. ”

“ We may for the present consider this question apart from ideas of derivation and elevation into higher planes of existence. Eozoon as a species, and even as a genus, may cease to exist with the Eozoic age, and we have no evidence whatever that any succeeding creatures are its modified descendants. As far as their structures inform us, they may as much claim to be original creations as Eozoon itself. Still descendants of Eozoon may have continued to exist, though we have not yet met with them. ”

“ The Laurentian fossil known as Eozoon Canadense (see Fig. 3) may have been the skeleton of such a lowly-organized animal; and if so, it is the oldest living thing that we know. But if really the [109] skeleton or covering of such an animal, Eozoon is larger than any of its successors, and quite as complex as any of them. There is nothing to show that it could have originated from dead [110] matter by any spontaneous action, any more than its modern representatives could do so. ”

“ 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. ”

“ There is no link in geological fact to connect Eozoon with any of the Mollusks, Radiates, or Crustaceans of the succeeding Cambrian. 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 Cryptozoum and some forms of Stromatopora; and here, as already stated, the evidence of minute structure fails to a great extent. ”

“ 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 « 149 » 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. ”

“ Although, therefore, the layers which contain well characterised Eozoon are few and far between, there is reason to believe that in the composition of the limestones of the Laurentian it bore no small part, and as these limestones are some of them several hundred feet in thickness, and extend over vast areas, Eozoon may be supposed to have been as efficient a world-builder as the Stromatoporæ of the Silurian and Devonian, the Globigerinæ and their allies in the chalk, or the Nummulites and Miliolites in the Eocene. ”

“ 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. ”

“ The Eozoön Canadense is found in the Laurentian rocks of Canada, other species in the Huronian of Bavaria, and specimens have been described from the Adirondacks and from Massachusetts. Forms strikingly resembling Eozoön may be found in the serpentine ledge in Fifty-ninth Street, near Tenth Avenue, New York. The soft parts in the calcareous skeleton of this Rhizopod have been replaced by minerals, and on the resemblance, amounting almost to identity, between the Eozoön and certain mineral pseudomorphs are based the objections made to its acceptance as of organic origin. ”

“ 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 positive opposition—though the latter has been smaller in amount than might have been anticipated, when we consider the novel and startling character of the facts adduced. ”

“ 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 conical or club-shaped forms, and that the broader patches were penetrated by large pits or oscula, admitting the sea-water deeply into the substance of the masses. ”

“ 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. ”

“ Perhaps nothing excites more scepticism as to the animal nature of Eozoon than the prejudice existing among geologists that no organism can be preserved in rocks so highly crystalline as those of the Laurentian series. ”

“ Therefore in these warm seas there must have been minute animal or vegetable organisms which Eozoön could gather with its long nets or lines, as it grew at the bottom of the sea. Was the Eozoön beautiful? We cannot speak positively; but as we find no age of the world when there was not beauty of form and color, as we see beauty often followed as an end in creation, we may suppose that the Eozoön had gay colors and looked like some great vivid flower waving upon its stem in the water. [8]
There are beds of limestone in the Laurentian rocks, which bear indications of former animal life. ”

“ 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. ”

“ 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. ”

“ They form a most suitable basis for - 259 - 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. ”

“ 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. ”

“ IN the Grenvillian system, as represented in the vicinity of the Ottawa River, perfect specimens of Eozoon are found in one only of the principal limestones there exposed, and in certain layers of that limestone, and they are associated with concretions and grains of the greenish mineral serpentine, which, as we shall see, has much to do with their preservation. ”

“ But while Eozoon thus preaches of progress and of development, it has a tale to tell of unity and sameness Just as Eozoon lived in the Laurentian sea, and was preserved for us by the infiltration of its canals with siliceous mineral matters, so its successors and representatives have gone on through all the ages accumulating limestone in the sea bottom. To-day they are as active as they were then, and are being fossilised in the same way. The English chalk and the chalky modern mud of the Atlantic sea-bed, are precisely similar in origin to the Eozoic limestones. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ 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, « 178 » 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. ”

“ 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 ”

“ 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. ”