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The temperate and arctic worlds, on the other hand, are a mere passing accident in the history of our planet: a hole-and-corner development; a special result of the great Glacial epoch, and of that vast slow secular cooling which preceded and led up to it, from the beginning of the Miocene or Mid-Tertiary period. Our European ideas, poor, harsh, and narrow, are mainly formed among a chilled and stunted fauna and flora, under inclement skies, and in gloomy days, all of which can give us but a very cramped and faint conception of the joyous exuberance, the teeming vitality, the fierce hand-to-hand conflict, and the victorious exultation of tropical life in its full free development.

All through the Primary and Secondary epochs of geology, it is now pretty certain, hothouse conditions practically prevailed almost without a break over the whole world from pole to pole. It may be true, indeed, as Dr. Croli believes (and his reasoning on the point I confess is fairly convincing), that from time to time glacial periods in one or other hemisphere broke in for a while upon the genial warmth that characterised the greater part of those vast and immeasurable primaeval aeons. But even if that were so–if at long intervals the world for some hours in its cosmical year was chilled and frozen in an insignificant cap at either extremity–these casual episodes in a long story do not interfere with the general truth of the principle that life as a whole during the greater portion of its antique existence has been carried on under essentially tropical conditions. No matter what geological formation we examine, we find everywhere the same tale unfolded in plain inscriptions before our eyes. Take, for example, the giant club-mosses and luxuriant tree-ferns nature-printed on shales of the coal age in Britain: and we see in the wild undergrowth of those palaeozoic forests ample evidence of a warm and almost West Indian climate among the low basking islets of our northern carboniferous seas. Or take once more the oolitic epoch in England, lithographed on its own mud, with its puzzle-monkeys and its sago-palms, its crocodiles and its deinosaurs, its winged pterodactyls and its whale-like lizards. All these huge creatures and these broad-leaved trees plainly indicate the existence of a temperature over the whole of Northern Europe almost as warm as that of the Malay Archipelago in our own day. The weather report for all the earlier ages stands almost uninterruptedly at Set Fair.

Roughly speaking, indeed, one may say that through the long series of Primary and Secondary formations hardly a trace can be found of ice or snow, autumn or winter, leafless boughs or pinched and starved deciduous vegetation. Everything is powerful, luxuriant, vivid. Life, as Comus feared, was strangled with its waste fertility. Once, indeed, in the Permian Age, all over the temperate regions, north and south, we get passing indications of what seems very like a glacial epoch, partially comparable to that great glaciation on whose last fringe we still abide to-day. But the Ice Age of the Permian, if such there were, passed away entirely, leaving the world once more warm and fruitful up to the very poles under conditions which we would now describe as essentially tropical.

It was with the Tertiary period–perhaps, indeed, only with the middle subdivision of that period–that the gradual cooling of the polar and intermediate regions began. We know from the deposits of the chalk epoch in Greenland that late in Secondary times ferns, magnolias, myrtles, and sago-palms–an Indian or Mexican flora–flourished exceedingly in what is now the dreariest and most ice-clad region of the northern hemisphere. Later still, in the Eocene days, though the plants of Greenland had grown slightly more temperate in type, we still find among the fossils, not only oaks, planes, vines, and walnuts, but also wellingtonias like the big trees of California, Spanish chestnuts, quaint southern salisburias, broad-leaved liquidambars, and American sassafras. Nay, even in glacier-clad Spitzbergen itself, where the character of the flora already begins to show signs of incipient chilling, we nevertheless see among the Eocene types such plants as the swamp-cyprus of the Carolinas and the wellingtonias of the Far West, together with a rich forest vegetation of poplars, birches, oaks, planes, hazels, walnuts, water-lilies, and irises. As a whole, this vegetation still bespeaks a climate considerably more genial, mild, and equable than that of modern England.