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to have differed during the past—the lower being more persistent, or less variable, than the higher—so the same ratio will manifest itself in the future, the more highly organised passing by more rapid stages into newer and higher forms. Within the same limit of time the invertebrate may undergo less modification than the vertebrate, the aquatic less than the terrestrial, and the cold-blooded less than the warm-blooded; but all (by whatever process) must sooner or later pass into newer and higher forms, and man himself as certainly as the plants and animals that form the theme of his deliberations. If there exist a great Law of Progression—and all that palaeontology has revealed of the past or physiology taught of the present points to such an ordaining—it would be reversing our ordinary ideas of the permanence of nature to suppose such progression had come to an end when all its accompaniments and all the media through which it manifests itself remain unimpaired and persistent. And it would be equally at variance with all philosophical notions of natural history to suppose that a law which had operated alike on all the orders of life in the past would become partial and exempting in the present. It may startle some minds to hear the same argument applied to man as to the rest of the animate creation. The reverse, unfortunately, has been too long the fashion. The interests of science, as well as the sacredness of truth, demand, however, that where nature operates alike the student of nature shall not venture to obtrude with artificial " schemes of arrangement" and "lines of demarcation." Looking at it merely as a question of natural history—and this, be it observed, is the only way in which science can approach it —the future of the human race must be subject to the same laws of variation and progression as those which have governed and still continue to govern the extinctions and evolutions of the other orders of vitality. The rate of variation may differ in the respective orders, but from the law of variation there can be no possible exemption. And this rate of variation has hitherto been more rapid in the higher than in the lower orders, the existing varieties of man must consequently the sooner pass into other and higher varieties.

In the last place, a new and important element must ever be taken into account in all our reasonings respecting the future flora and fauna of the globe. During the old geological epochs the "Law of Development," or whatever else it may be termed, exerted iteelf universally, and this without control or interference by human operations. Now, however, and during the current epoch, man comes in as a modifying and sub-creative agent—here removing and extirpating, there transferring and multiplying, and this the more signally the more settled and civilised he becomes. Observe what changes must have taken place since civilised man first took possession of Asia and Europe, and how much more since, under the impulse of modern progress, he has carried his efforts to America and Australia! The natural flora of a region must make way for his cultivated plants, and the fauna for his domesticated animals. Here he reclaims and extirpates, and this extirpation reacts in a hundred ways on the surrounding fauna. There he transfers and acclimatises, and in a few generations the plants and animals of the Old World flourish and multiply in the New, and by reciprocation those of the New World become equally prolific in the Old. Here he destroys the plant, and the animal deprived of its food shifts ground or dies out; there he introduces a new animal, and, in the struggle for existence, some weaker and less elastic species succumbs before the intruder. Of course, there are great climatal limits to this transference, which the utmost ingenuity of man cannot pass, but there is no possible end to his extirpations and modifications; and thus in the lapse of time the natural course of vital development and distribution will be extensively interfered with by the operations of man. But extensive as may be his interference, he cannot overrule the great Law of Progression any more than he can prevent the physical operations by which the continents themselves are continually modified. The law will go irresistibly forward, carrying man in hisseveral varieties along with it; employing, it may be, his influence as a pre-ordained portion of its operations, but still methodically ascending from higher to higher, till the future aspects of life differ as widely from those of the present, as its present aspects differ from those that preceded.

Such are the leading features of the future, which, reasoning from the order of the past and the appointments of the present, Geology is enabled to indicate—new distributions of sea and land, new climates and physical surroundings, new and higher orders of plants and animals; but all these brought about so slowly and gradually that the qhanges become apparent only after the lapse of ages. The present, so far as we can judge, is as fluctuating as the past, and yet the oldest scenes of human history—India, Mesopotamia, the valley of the Nile, the shores of the Levant, Greece, and Italy — remain in all their broader features much as they were three thousand, four thousand, and six thousand years ago. So tranquil, indeed, are the great physical progressions of nature that it requires some mental effort to perceive them; so gradual the vital, and through so many intermediate stages, that it demands an exercise of reason to admit their reality. But when once perceived, how enlarged our conceptions of the universe—a system of incessant fluctuation and progress in its details; a system of stability and permanence in its general appointments! To the ignorant mind, alluded to by Dr Hutton in our opening quotation, the earth is a mere monotonous panorama of birth, progress, and decay—the same now as it has been from the beginning, and as it is now so to continue unchanged and unchangeable to the end. To the enlightened mind, on the other hand, it becomes a scene of incessant development and progress—multiform and variable in its physical relations, diversified and progressive in its vital appointments, and still at every turn assuming more wonderful and more exalted aspects. How much more ennobling this conviction of our planet's incessant mutation and progress than the old belief in its stereotyped sameness and ever-threatened decay! How enlarged the conceptions of Creative Wisdom inspired by a knowledge of these ever-varying and ever-advancing aspects—these endless adaptations and boundless resources! And how much more when we carry our views from this world of ours to the other members of the planetary brotherhood, and believe them subject to similar laws, and characterised by similar appointments! To the eye of sense they are mere balls swinging clearly and coldly in space; to the eye of enlightened reason they become, like their sister orb, multiform in the details of their terraqueous surfaces, variable in their physical and vital aspects, and yet throughout all their variability invariably conforming to a higher law of development and progress.

INDEX.

Abbeville flints and flint-formers, 296.
./Epiornis,extinction of, in Madagascar,

274.
Agassis, " monograph of fossil fishes,"

129.
Agents modifying the earth's crust, 38.
"Age of mammals," the, 207.
** Age of reptiles," the, 193.
Amber, its relation to lignitic beds,
. 211.

Ammonites of secondary systems, 193.
Animals and plants of the future, 328.
Animals, systematic classification of,

124.
Anthracitesas distinguished from bitu-
minous coals, 153.
Antiquity of man, relative notabsolute,

296.
Antiquity, relative, of rock deposits, 85.
Aqueous agencies, their operations, 40.
Archaeopteryx, or fossil bird of oolite,

196.
Atmosphericagencies, their ope rations,

38.
Atmospheric denudation, effects of, 53.
Auk, great, probable extinction of, 274.
Avalanches, formation and varieties of,

219.
Azoic rocks, definition of, 97.

Barrier reef of New Holland, 268.
Basins, tertiary, illustrations of. 204.
Beaches, raised, ur ancient sea-margins,

263.
Bergrap, the, of Norway, 217.
Bird-life of secondary periods, 195.
Bone-shoals and osseous breccias, 268.
Botanical classification, 121.
Boue, his description of glaciers, 222.
Boulder-clay or lower " till," 234.
Bovine period in European geology,

298.
Bovine stage of post-tertiary epoch,

298.
Brick-clays of the glacial period, 238.
Britain's mechanical supremacy, and

her coal-fields, 177.

Bronze, stone, and iron nges, relative

antiquities of, 291.
Brown coals or lignites, nature of, 167-
Browne on ice-caverns, quoted, 223.
Burrh-stone of tertiary formations,

211.

Cainozoic formations, definition of, 26,
29.

Calc-tufa and calc-sinter, 262.

Cambrian system, its rocks and fossils,
91.

Can n el or parrot coal, 154.

Carboniferous or coal-period vegeta-
tion, 167.

Carboniferous period, its probable phy-
sical conditions, 170.

Carboniferous system, subdivisions of,
161.

Carses of Scotland, their formation,
256.

Cave-bear, extinction of, in Europe,
273.

Cave-earths and cave-dwellers of Eu-
rope, 295.

Cave-lion, extinction of, in Europe,
273.

Cephalaspis, old red sandstone fish,
138.

Chalk or cretaceous system, its com-
position, 190.

Chambered shells of secondary ages,
193.

Chemical action, metamorphic effects
of, 71.

Chemical agencies, their operations, 42.

Chronological arrangement of rock-
formations, 29.

Chronology of geology, relative nature
of, 286.

Chronology of rock-formations, how
determined, 26.

Classification of rock-formations, 29.

Cleveland ironstone district, 199.

Climate, periodical oscillations of, 245,

Climatic character of the future land-
masses, 326. .. .

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