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extinctions have taken place, and this altogether apart from the effects produced by man's cultivation and domestication. The wild-boar, wild-ox, bear, wolf, and beaver have disappeared from Britain; and every century their tenure of Europe becomes more slender and uncertain. The dodo has become extinct in the Mauritius, the solitaire in Rodriguez, the æpiornis in Madagascar, the dinornis in New Zealand, the Phillip's Island parrot from Australia, and the rytina from the rivers and estuaries of Kamtschatka. And as with these, so it will shortly be with others whose circumscribed ranges are gradually being broken in upon by new conditions, imposed either by natural change or by man's progress and civilisation. The apteryx of New Zealand, the ornithorhynchus, echidna, and kangaroo of Australia, the mooruk of New Britain, the ostrich, elephant, and giraffe of Africa, the anrochs of Europe, the beaver and bison of America, the musk-ox of the arctic regions, and many others, look more like the residuary forms of the tertiary, than the advancing species of a newer era. And as with animals, so it has been and will be with many plants (the gigantic Wellingtonia, for instance, confined to a few narrow valleys in California); only we have been less observant of their mutations, and are merely beginning to note their specific restrictions.

As history has failed to note geological mutations and vital extinctions, so we ask her in vain for any evidence of new creations. No doubt, naturalists have now and then announced the "discovery" of a new species of plant or animal, but whether these were existing forms previously unnoticed, or new forms only recently introduced, the imperfection of history leaves us no means of determining. And yet, reasoning from our knowledge of the past, the appearance of new species must take place as infallibly as the disappearance of the old. So long as the energies of

nature continue unimpaired, the balance of vital activity must be maintained. Even man's extirpations and modifications, extensive as they appear, are in a great measure counterbalanced by his introduction and wider distribution of the cultivated plants and domesticated animals in all their endless varieties. The scheme of Life is as progressive now as it ever was, and man himself is as subject to its laws as the meanest form he modifies. The pre-historic nomades of Asia, the stone-implement makers of Europe, and the mound-builders of America, have passed away, and are less known to us in their aspects, thoughts, and doings than their contemporary mammoths, great deer, and wild oxen. The temple-rearing, idol-worshipping races of Babylonia, Egypt, and Central America, have perished, and their characters are merely beginning to be revealed to us; while our more immediate predecessors, the Greeks, Romans, Celts, and early Saxons, have partaken of the same doom, and much of their history remains in doubt and obscurity. Thus, physical features, habits of life, modes of thought, social systems, and religious beliefs-all that renders humanity distinctive, and confers on it its highest attributes—have ever been as mutable and progressive as the phases of nature by which they are surrounded; nor do the realities of the present exhibit the slightest symptom of persistence and finality. As the paleozoic passed into the mesozoic, and the mesozoic into the recent; so the recent is pressing on to a future, that will be stamped by features-physical and vital, social and moral-peculiarly its own.

Supposing, then, that science could determine all the physical and vital conditions of the earth-in other words, could read her history up to the present moment—the question naturally arises, How far we are entitled, in the spirit of philosophy, to presume on what is yet to follow ?

This brings us, in conclusion, to look at the earth's probable Future through her knowledge of her Past. As students of nature, we can no more refrain from this inquiry than we can cease to take an interest in her bygone history. The present is a mere evanishing point: yesterday it was the future, to-morrow it will be the past. Past, present, and future are but portions of one vast cycle of change; and could we determine with accuracy the rate of progress in the past, the future would be rationally computable. In the mean time our knowledge of world-history is far from perfect, hence our estimate of the future can assume at best little more than the character of speculation. Still, we are fairly entitled to hold that as the rocky crust has, under the operation of the physical forces, been the theatre of incessant change in the past, so it will continue to be subjected to similar mutations in the future. As we see no decline in the forces that operate, so reason refuses to admit a cessation of their results. Volcanic energy will shift its centres of activity; continents will be submerged; seabeds be uplifted into dry land; climatic influences be altered; living races will succumb to obnoxious conditions; and new ones will appear co-adapted to these newer phases. As in the past the changes were always gradual and local, and the newer phases ever bore a certain appreciable relation to those that went before; so in the future we may rely on a similar gradation, and believe that the differences between the phases yet to be will never exceed those geology has discovered between two successive formations.

As with the physical, so with the vital forces. Age after age has been characterised by its own peculiar phases of vitality, and as we fail to detect any symptom of decline, so we may fairly presume that the future aspects of life will differ from that which now prevails, as that which exists differs from that which preceded. As the course has ever been to

higher and higher forms, so the life of the future must transcend that of the present, as the present excels the past. Unless geology has altogether misinterpreted the history of this earth, and her teachings be no better than a fable and delusion, philosophy is chained to this conclusion. Could we discover the terms of the law that has regulated the evolutions of past vitality, we might approximate to some idea of its future forms; but, ignorant of these terms, we can only rely on the upward progress of life, and believe that its newer phases will retain the same appreciable relations to the present that the present does to the age immediately preceded. The great primal patterns-radiate, articulate, molluscan, and vertebrate-will ever remain the same: their modifications seem endless, their adaptations interminable.

that

THE LAW.

HAVING reviewed in detail the life-phases of the successive epochs of geology, we now proceed to a few generalisations respecting the advent and exit—the rise, progress, and decay-of specific vitality. In so doing, we shall endeavour to give expression to some of the leading laws which seem to have influenced Life since its first appearance on the terraqueous globe, believing that details are of themselves comparatively worthless unless we can co-relate and connect them into something like order and system. I am fully aware, where so much of our evidence is merely negative, and where more, perhaps, is still fragmentary and imperfect, that any attempt of this kind may be thought premature and perhaps presumptuous. But the law of our nature, like the law of creation, is ORDER; and the mind instinctively groups and associates, and tries to connect ef fects with their causes, the moment it turns itself to any new field of research. And so, in Palæontology, these generalisations, however tentative and temporary, serve as centres round which to marshal new facts, and help to give consistency and interest to what might otherwise appear a mass of discordant and repulsive details. And granting that many of these generalisations may be set aside by future discoveries, so long as they are received in the same spirit in which they are submitted, they cannot retard the

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