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edges of the strata would abut against this slope, and ultimately both they and the early shallow water deposits on the higher terrace would be covered over by the Birdseye, Black River, Trenton, Utica, and Hudson River formations, as represented in the accompanying diagram, (fig. 3.)

[graphic]

p1, Black shales and limestones. (Potsdam.)

g, Gneiss, (Laurentian.)

Magnesian conglomerates and shales.
Sandstones and magnesian conglo.
Green and gray shales and sandstones.
p2, Sandstones.
Green shales.

Sandstones and red shales (Sillery),
Red and green shales.

Quebec group

Limestones (Birdseye Black River and Trenton.)
u, Dark gray shales and sandstones, (Hudson River.)
L', At the level of the sea during the Potsdam period.
Black Shales (Utica.)

Without enquiring into the origin of the forces which have produced the corrugations of the earth's crust, we may suppose that if a sufficient lateral pressure were applied to strata thus accumulated and arranged, there would result a set of parallel folds and overlaps, running in a direction at right angles to that of the pressure, with prevailing overturn dips in the direction of movement; the greater strength, however, of the solid crystalline gneiss in this particular case, offering more resistance than

L2,

at the commencement of the Calciferous.

the newer strata, would cause a break coinciding with the inclined plane at the junction of the gneiss and Quebec group; the strata of this group pushed up the slope would raise and fracture the strata of the formations above, and be ultimately forced into an overlap of that portion resting on the higher terrace, after probably thrusting over to an inverted dip that part of the upper beds with which they came in contact. The strata of the upper terrace, relieved from pressure by the break, would remain comparatively quiescent, and thus the limit of the more corrugated area would coincide with the slope between the deep and shallow water of the Potsdam period. But the resistance offered by the gneiss would not merely limit the main disturbances, it would probably also guide or modify in some degree the whole series of parallel corrugations, and thus act as one of the causes giving a direction to the Appalachian chain of mountains.

REVIEWS AND NOTICES OF BOOKS.

Life on the Earth, its Origin and Succession, by JOHN PHILLIPS A.M., LL.D., F.R.S., Late President of the Geological Survey and Professor of Geology in the University of Oxford.

This volume contains the substance of the Bede Lecture, delivered at Cambridge, in May 1860. Like everything that Prof. Phillips does, it is clear, accurate and scholarly. It gives in small compass and in a manner intelligible to all, a summary of the facts known to Geology respecting the introduction and order of succession of life on the earth, without any of the exaggeration and looseness of statement too common in popular books. It can be safely recommended to every one desirous of knowing the present state of this subject, and its bearing on the Darwinian doctrine of the origin of species by natural selection. The work might afford many interesting extracts, but we content ourselves with copying the Author's concluding reflections, which are full of great truths, and with recommending our readers to procure the work for themselves.

"These various speculations on the subject of Fossil plants and animals, and the origin and progress of life, may perhaps, to the student of exact science, appear little more than the chase of a phantom, a wandering after unattainable truth. There is, however, something seduc

tive in the problem of the origin of life, and one who has entered on this charmed path, will seldom leave it without reluctance. Vain and ill-judged as are some of these attempts, they ought perhaps not to be visited with the heavy condemnation which sometimes has been heaped upon them. Men may have mistaken views about the diluvial catastrophe; false conceptions regarding electricity as the agent of imparting life; wrong notions about the nature of atoms, and yet not reason, at least intentionally, as 'atheists,' denying the incessant watchfulness of God over the arrangements which he has appointed. It is hard to believe this of any serious thinker, even of Lucretius, however strongly he may contend for the regular operation of natural laws, in opposition to the capricious meddling of those monstrous personifications of human passions, which were accepted for deity by the 'too superstitious' men of Athens and Rome. Erroneous opinions have but their day, and are, perhaps less mischievous, than the indolence which acquiesces in dull and incurious conformity with whatever may reign for the moment. Truth, or what appears such to human reason, operating on real facts and just inferences, this is the end of scientific research; while we seek it, let us not be too much troubled if some run in courses wide of our own, and ask questions we think not likely to be answered. If we do not ourselves believe the origin of created life to be discoverable by a creature limited to the observation of sensible phenomena, why should we restrain the enterprise of those who, vainly striving after something that is unattainable or fabulous, may yet win much that is accessible, valuable and real?

"According to most of the hypotheses we have been considering, the forms, structures and habits of life, which we now circumscribe by specific characters, however distinct these may seem to be, are only constant for this moment, slowly varying through this period, as they have varied in preceding periods, possibly then at a greater rate than now. The forms that now are have had a long series of progenitors, gradually changing from the earliest times; many of the earlier races of a great common stock having died out, while others came into view; the whole theatre of life always full of action, but the actors continually changing, however slow the process of change.

"But, as already observed, the evidence of most value for deciding the probability of such a progressive change in the forms of life is to be furnished by geology. That it does not furnish good evidence in favour of gradual and indefinite change is perhaps generally allowed; but that it does furnish evidence of interrupted and limited change, and that the changes mark steps of progress, is a prevalent opinion. It is the opinion of Mr. Darwin, that if the record of life in the fossiliferous strata were complete, those changes which now appear interrupted and sudden would be found to have been continuous, and the progress by steps would become an inclined plane of easy ascent. This incompleteness he assumes to be enormous; so much so that the traces of whole periods of immense duration, including the first period, are lost; what we possess being merely fragments of the record, which indeed never was

complete, owing to the character of some kinds of deposits. Thus we must not expect to be able to arrange the fossil remains in a real however broken series, since the true order and descent may be, and for the most part is irrecoverably lost.

"Surely this imperfection of the geological record is overrated. With the exceptions of the two great breaks at the close of the Palæozoic and Mesozoic periods, the series of strata is nearly if not quite complete, the series of life almost equally so. Not indeed in one small tract or in one section; but on a comparison of different tracts and several sections. For example, the marine series of Devonian life cannot be found in the districts of Wales or Scotland, but must be collected in Devonshire, Bohemia, Russia, and America. When so gathered it fills very nearly if not entirely the whole interval between the Upper Silurian and the Carboniferous Fauna. So in England the marine intermediaries of the Oolitic and Cretaceous ages are not given: but the Neocomian Strata supply the want. We have no Meiocene Strata in England, but their place is marked in France and America.

"Even the great breaks alluded to are bridged. The Permian series of life contains some Mesozoic interpolations; and the Lias contains reliquiæ of some Palæozoic genera. The upper chalk of Maestricht and the South of France extends toward the Tertiaries the reign of the Upper Mesozoic beds.

"On the whole, it appears that there exist ample materials for testing any hypothesis of the sequence of life which includes the marine races; and that there is much ground for believing, in regard to the chasms which do exist in the series of freshwater and terrestrial races, that if filled, they would not lead to other inferences than such as appear consistent with the records of the sea. If the monuments of the earlier life of the globe are essential witnesses, but too few and independent for a satisfactory test of a given hypothesis of the sequence of life, it is unfor tunately ineligible for admission among accepted truths.

"Caloric, electricity, chemical action, are all influential on life; elevating and depressing it, carrying it on or bringing it to a close, according to the measure and mode of application of these powers of nature. Employed as they are in the current of life, and at every moment acting on and being acted on by it, nothing has seemed easier to speculation than to conceive these agencies so operating on appropriate matter as to make the vital machine which could not be kept in motion without them. The only thing wanted is the due co-ordination of these powers, in the appropriate matter. Here unfortunately is the difficulty-due co-ordination of independent powers in matter rightly adapted implies the directing mind of the Master of power and matter. The formula is imperfect

We start, for LIFE is wanting there

"Given, however, the appropriate matter, and the stroke of life upon it, what have we-no living thing-but vitalized matter. Capable of what? Self-development? Into what simple organic form? The anCAN. NAT. VOL. VI. No. 3.

4

swer seems to have been an Infusory Animalculum, before the scrutiny of the microscope had shewn the real complexity of most of these children of unknown fathers, the transition stages of others, the definite course of life of all. At present the first hopeful product of the cryptogamy of electricity and carburetted moisture would be a fertile cell, for cells are the ultimate term of the mechanical analysis of organic beings. "Given then a cell with walls; composed of carbon, hydrogen and oxygen; capable of self-division and so of increasing in number. Let it be born in the sea according to Telliamed, or, in moisture, or slime, according to Lamarck, or if it suit better the following phenomena, in the air. What follows? An aggregation of cells. Plant or animal? Perhaps neither, but a living being, capable not of moving, but of being moved, says Lamarck, by the external powers influential on life, like Volvox. What next? Reproduction of other Volvoces by self-division, or the growth of new individuals within the parent.

"Here the process, so far as our knowledge and observation go, at present, must stop-the aggregate of cells breaks up into smaller aggregates, or is resolved into solitary cells again, and our little circle of discovery is completed.

"Given, therefore, something more; a current of water guided by cilia through the mass; removal and renewal of cells; addition of a new substance to line the canals, in forms determined by these currents; the growth of germs capable of being separated and going through the same series of events; in short a sponge, for the possession of which Botany and Zoology have had a long conflict, and which seems placed at the very lowest limit of specific life.

"What is the next step, or rather leap, is hard to say; for if we go to the minute Foraminifera, that is a group of aggregated and perforated shells, with cilia, which helps us very little or not at all in the advancement of animalization; but if we ascend per saltum to the Zoophyta most allied to Spongiadæ, and claim affinity with Alcyonium, we require the large postulates of freely moving polypi, with eight arms round the contractile mouth, a complete digestive cavity, and ova of definite character.

"Then again is another hiatus between the Alcyonidæ and the Mollusca, which neither fossil nor recent life can fill; and thus in what seem to be the first and easiest steps we can imagine, nothing but postulate upon postulate will bring us on our way. But postulates in the sense here used are equivalent to special endowments, not in the least easier to conceive of than separate creations; for what are these but endowments, and has not every special structure its appropriate germ and mode of growth?

"If it is not possible in the existing ocean, among the innumerable and variable radiated, amorphozoan, and foraminiferous animals, to construct one chain of easily graduated life, from the fertile cell to the prolific ovarium and digestive stomach, it must be quite in vain to look for such evidence in the fossil state. In the face of the assumptions requisite to imagine such a chain, we cannot venture to adopt it as a

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