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now in progress, and is divisible into two parts; the first of which comprehends all questions relating to the variability of species and the limits assigned to their duration, as well as the effects produced by the powers of vitality on the state of the earth's surface: while the second explains the processes by which the remains of animals and plants existing at any particular period may be preserved or become fossil; and the work concludes by a lucid and interesting account of the formation of coral reefs.
With regard to the Manual of Elementary Geology,' in which is included the matter of the Fourth Book of the first edition of the * Principles,' we may repeat emphatically, after profiting by its study, the author's statement that it is not an epitome of the • Principles of Geology, nor intended as introductory to that work; and we beg to add our conviction that it is the best elementary work of instruction in the science of Geology, whether in regard to the clearness and intelligibility of the definitions and descriptions, the arrangement of the topics, the comprehensive grasp of the divisions and relations of the science, the masterly ease of the style throughout, or the number, accuracy, and beauty of the woodcuts incorporated with the text.
The Principles and the Manual, in their present form, are each complete in itself, and only relate to one another inasmuch as, if the student should ask which he should read first, their author recommends him to begin with the Principles, as he may then proceed from the known to the unknown, and be provided beforehand with a key for interpreting the ancient phenomena whether of the organic or inorganic world, by reference to changes now in progress.
Some may object that the student would thereby be liable to get a bias in favour of the uniformitarian views which characterize Sir Charles Lyell's explanations of the phenomena of geology. We do not participate in any fear of or dislike to such a bias being impressed on the mind of the beginner, deeming it a salutary counterpoise to that innate tendency to view the stupendous results of the forces that have affected the earth's crust in relation to the requisite amount of force, without due reflection on the time over which that force may have been diffused in producing the effects witnessed.
It is well that the student should know something of the nature of the various forces now more or less actively operating in changing the inorganic world. If any prepossession is to be deprecated, as likely to result from his introduction to geology by Sir Charles Lyell's Principles,' it is in reference to the organic world. Little, very little comparatively, is known of the circumstances that have led to the extinction of organic species, and absolutely nothing of the causes of the introduction of new species, or whether secondary causes have therein operated at all. Yet there is a strongly marked tendency throughout the writings of Sir Charles Lyell to apply the same principles in explanation of the changes in the organic world which he has applied with so much, and often so unexpected, success to those of the land and sea. Herein is shown, we think, the least favourable feature of his work, although it is comparatively masked in the edition before
The author has, however, in his last Anniversary Address to the Geological Society, brought out his uniformitarian views as applied to plants and animals, in formal and direct opposition to what he admits to be the prevalent but believes to be an erroneous interpretation of the facts of Palæontology. We conceive it our duty, therefore, to take up the gauntlet which Sir Charles has thrown down, and we do so with the more readiness, as his challenge forms a prominent feature in the Edinburgh Philosophical Journal for July 1851, where it appears without any sign of dissent on the part of the able and experienced editor, Professor Jameson.
Sir Charles, in illustration of the doctrine which he assails, viz., that “a gradual development in the scale of being, both animal and vegetable, from the earliest periods to our own time, can be deduced from palæontological evidence, cites recent works by Sedgwick, Owen, and Hugh Miller. The passage most to the point, from the celebrated Discourse on the Studies of the University of Cambridge, is as follows:
• The elevation of the Fauna of successive periods was not made by transmutation, but by creative additions ; and it is by watching these additions that we get some insight into Nature's true historical progress. Judging by our evidence (and by what else have we any right to judge ?) there was a time when Cephalopoda were the highest type of animal life. They were then the Primates of this world, and, corresponding to their office and position, some of them were of noble structure and gigantic size. But these creatures were degraded from their rank at the head of Nature, and Fishes next took the lead : and they did not rise up in Nature in some degenerate form, as if they were but the transmuted progeny of the Cephalopoda, but they started into life in the very highest ichthyic type ever created. Following our history chronologically, Reptiles next took the lead—and (with some almost evanescent exceptions) they flourished during the countless ages of the secondary period as the lords and despots of the world; and they had an organic perfection corresponding to their exalted rank in Nature's kingdom; for their highest orders were not merely great in strength and stature, but were anato
VOL. LXXXIX. NO. CLXXVIII.
mically raised far above any forms of the Reptile class now living in the world. This class, however, was, in its turn, to lose its rank; what is more, it underwent (when considered collectively) a positive organic degradation before the end of the secondary period—and this took place countless ages before terrestrial mammals of any living type had been called into being. Mammals were added next (near the commencement of the tertiary period), and seem to have been added suddenly. Some of the early extinct forms of this class, which we now know only by ransacking the ancient catacombs of Nature, were powerful and gigantic, and we believe they were collectively well fitted for the place they filled. But they, in their turn, were to be degraded from their place at the head of Nature, and she became what she now is by the addition of Man. By this last addition she is more exalted than she was before. Man stands by himself the despotic lord of the living world; not so great in organic strength as many of the despots that went before him in Nature's chronicle, but raised far above them all by a higher development of the brain-by a framework that fits him for the operations of mechanical skill-by superadded reason-by a social instinct of combination-by a prescience that tells him to act prospectively—by a conscience that makes him amenable to law--by conceptions that transcend the narrow limits of his vision-by hopes that have no full fruition here—by an inborn capacity of rising from individual facts to the apprehension of general laws-by a conception of a cause for all the phenomena of sense- —and by a consequent belief in a God of Nature. Such is the history of Creation.' ---Sedgwick,
We take next the quotation from Miller :
• It is of itself an extraordinary fact, without reference to other considerations, that the order adopted by Cuvier in his Animal King. dom as that in which the four great classes of vertebrate animals, when marshalled according to their rank and standing, naturally range, should be also that in which they occur in the order of time. The brain, which bears an average proportion to the spinal cord of not more than two to one, came first : it is the brain of a fish; that which bears to the spinal cord an average proportion of two-and-a-half to one, succeeded it: it is the brain of a reptile ; then came the brain averaging as three to one: it is that of the bird. Next in succession came the brain that averages as four to one: it is the mammal; and, last of all, there appeared a brain that averages as twenty-three to one;-reasoning, calculating man had come upon the scene.'-Foot-prints of the Creator,
The paragraph cited from Owen's · Nature of Limbs' we do not repeat, as it merely states, in reference to the vertebrate subkingdom, that the fish was the form first introduced. If it be true, as is most probable from the caution and
experience of Mr. Logan, the chief of the Government Survey in Canada, that the portion of the Montreal or Potsdam sandstone, bearing the impressions of an air-breathing quadruped, is, as Sir
Charles Lyell had previously stated, of the same age as the lowest Silurian deposits in this country, then, according to the interpretation of those footprints given by Professor Owen, * a coldblooded reptile, probably chelonian, was coeval with the oldest known fish. And the generalization, according to actual evidence, would be, that the cold-blooded vertebrata preceded, by a long series of
the warm-blooded ones. Sir Charles Lyell, however, goes farther, and repudiates the theory of successive development of organic life; and, as he premises a brief preliminary statement of the principal points which he expects to establish in opposition to that theory, we shall, in the remainder of our article, confine ourselves to an examination of their value.
. First, in regard to fossil plants, it is natural that those less developed tribes which inhabit salt water, should be the oldest yet known in a fossil state, because the lowest strata which we have hitherto found happen to be marine, although the contemporaneous silurian land may very probably have been inhabited by plants more highly organized.
* Secondly, the most ancient terrestrial fora with which we can be said to have any real acquaintance (the carboniferous) contains coniferæ, which are by no means of the lowest grade in the phænogamous class, and, according to many botanists of high authority, palms, which are as highly organized as any members of the vegetable creation.
Thirdly, in the secondary formations, from the triassic to the Purbeck inclusive, gymnosperms allied to Zamia and Cycas predominate; but with these are associated some monocotyledons or endogens, of species inferior to no phænogamous plants in the perfection or complexity of their organs.
· Fourthly, in the strata from the cretaceous to the uppermost tertiary inclusive, all the principal classes of living plants occur, including the dicotyledonous angiosperms of Brongniart. During this vast lapse of time four or five complete changes of species took place, yet no step whatever was made in advance at any one of those periods by the addition of more highly organized plants. --Address, 21.
With respect to these propositions, we would in the first place remark that organised beings constitute one great natural assemblage of objects. Plants cannot be distinguished from animals except by special definitions, of which there have been several, founded, -e. 9., on sensation and motion,--on the stomach,--on the respiratory products,-on the chemical constitution of the tissues, -on the sources of nutriment, &c.,-each of which definitions draws the boundary line at a different latitude of the debateable ground. No generalization touching the progression of life on this planet can be materially affected by the phenomena
Appendix to Sir C. Lyell's Address; and Proceedings of the Geological Society, April 30th, 1851.
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of one particular group of living beings, least of all by the lowest group.
Plants are the lowest forms of organic life: Vegetabilia crescunt et vivunt, non sentiunt : the system by which the individual takes cognizance of the things around it, and puts itself in sentient relation with them, has not begun to appear in any of the botanical orders or families. Progress in the organic scale could not be exemplified in any great degree within the limits of the vegetable kingdom ; and it would be no argument against conclusions based on a survey of the animal world from its earliest traces on our planet to its actual condition, if even the so-called highest forms of plants had been discovered in the same strata with those first evidences of animal life.
Such discovery, however, has not yet been made. All that we at present know of the vegetation of the globe at the period of the earliest known fossiliferous deposits is that it was of that more simple or less developed kind which characterises the tribes growing in the sea. No doubt the lowest strata which we have hitherto found happen to be marine ; but it helps us very little forward in the solution of the great question of stationary or progressive creation to suggest that the contemporaneous silurian land may very probably have been inhabited by plants more highly organized; because those plants may also, with some probability, have been lichens, mosses, ferns, or forms at least of a kindred grade of organisation. We do not know what they were, and our hypotheses must wait until
The most ancient terrestrial flora with which palæontologists have any real acquaintance is that of the carboniferous period; and this contains coniferæ, which, although by no means the lowest of the phænogamous class, are still far from being ranked amongst the highest. Whether some of the fossil coal plants are referable to the family of true Palins is a point as yet not so clearly determined.
But if botanists of the highest authority were all agreed as to the existence of those highly organised members of the vegetable creation at the carboniferous epoch, as they are respecting the predominance of gymnosperms allied to Zamia and Cycas in the secondary beds, from the triassic to the Purbeck inclusive, and in regard to the presence of exogens and dicotyledonous angiosperms in the cocene tertiary formations, and of trees resembling the Cinnamomum and Podocarpus in the miocene strata,—these facts would still leave the question of the progression of organisation unaffected. But of the 500 species of coal plants to which the critical and scrupulous investigations of Adolphe Brongniart have restricted the fossil evidences, one half at least are ferns, and the greater part of the remainder are gym