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.

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 Cœnostroma 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.