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in chips and fragments even more fragmentary than when originally imbedded. Notwithstanding these obstructions, and the hopelessness of ever obtaining in a fossil state the colours and softer parts that give beauty and outline to animal forms in spite of the fact that the corresponding portions of structures found to-day may not be turned up even for years to come-and in face of the toil and expense which the study unavoidably entails-substantial progress has been made in Palæontology, and these fragmentary remains of Past Life been reconstructed so as to take intelligible rank and position in the great categories of existing Vitality. Founding on the uniformity of natural law and persistency in the main structural characteristics of plants and animals throughout all time, the Palæontologist, strong in his faith and hopeful of the result, proceeds to his arduous task, and resuscitates as it were the Life of former epochs— clothing the land with verdure and beauty, and peopling the waters with their varied and appropriate forms. Lifting the veil from the Past, he displays the terraqueous aspects of the globe at the successive stages of its history; even as now, through the combined labours of the geographer, the botanist, and the zoologist, we are enabled to present a panorama of existing lands and seas with all their exuberant and varied vitality.

THE PRESENT.

ITS FLORA, FAUNA, AND THEIR CO-ADAPTATIONS.

BEFORE we can rightly compare the Past Life, of which these relics give evidence, with that which now peoples the globe, we must glance at the conditions under which plants and animals at present exist, and know something of their nature and the functions they have to perform. We can only reason respecting the Past from our knowledge of the the Present; and the more intimate our acquaintance with the various phases of existing nature, the sounder our deductions relating to those that have long since passed away.

We say the various phases of existing nature, for the plants and animals that people the surface of any given latitude may differ altogether in character from those entombed in the strata beneath, and the organisms in the several formations below may now find their nearest analogues in the flora and fauna of distant and diversified regions. If we are familiar, however, with the general conditions under which plants and animals now live and flourish, and if we can establish a relationship between those existing and those long since extinct, then we can recall the conditions under which the latter grew and flourished, and map out the geography and climate of the primeval world, as the geographer now maps out the areas of sea and land, and depicts the various races of life—the belts of sterility and exuberance-and the creative centres

from which peculiar families have emanated to perform their functions in the great economy of nature.

I.ITS FLORA OR PLANT-LIFE.

Glancing first at the VEGETABLE WORLD, we perceive that the great regulators of plant-life are heat, light, and moisture. Such is the order of nature now, and such, we are bound to believe, have been the ordainings of creation from the earliest moment that the vegetable cell was evoked into existence. Under the tropics, both individual exuberance and specific variety attain their maximum intensity; in the temperate zones this intensity gradually declines; while in the arctic regions vegetable life dwarfs and diminishes till. it ultimately disappears and gives place to utter sterility. As we start from the equator, each great belt-equatorial, tropical, subtropical, warm-temperate, cold-temperate, subarctic, arctic, and polar*-presents its own distinctive features; and though the zones of the southern hemisphere may differ in genera and species from those of the northern, there is still in the respective stages a sufficient resemblance of growth, colouring, and inflorescence, to prove that, latitude for latitude, the prime governing influence is essentially solar. As with latitude, which is influenced in the main by light and heat, so with height above the level of the ocean-an advance upwards into the rarer regions of the atmosphere being equivalent, in some measure, to an advance northwards or southwards into the colder latitudes

* The equatorial zone extends on both sides of the equator to about 15° of latitude; the tropical from 15° to the tropics; the subtropical from the tropics to 34°; the warmer temperate from 34° to 45°; the colder temperate from 45° to 58°; the subarctic from 58° to the polar circle; the arctic from the polar circle to latitude 72°; and the polar zone from 72° to the poles.

of either pole.* The mountain that has its base waving with the palms and tree-ferns of India, may have its sides clothed with the oaks and pines of Europe, its higher cliffs with the dwarf-willows and mosses of Nova Zembla, while its snowy peaks are as void of life as the ice-bound shores of the arctic circle. Besides these conditions, there are others of site, or locality, or habitat-conditions which require that the weeds of the ocean should differ from the plants of the marsh, the plants of the marsh from the herbage of the open plain, and the verdure of the plain distinct from that of the mountain forest. Nay more : there are some tribes that will flourish only in rich organic mould, others that prefer the shingly surface of the arid desert; some that exist only on calcareous soils, and others unknown beyond the limits of the salt marsh. Wherever the prime conditions of heat, light, and moisture are present, there the vegetable germ manifests itself-here incrusting the naked rock, there mantling the surface of the stagnant pool-now rooting itself in the decay of its own kind, and at times finding a habitat even in the tissues of the animal structure. More than this: every climatic influence, however faint, leaves its impress on vegetable life. A thicker layer. is added to the concentric growth of the timber-tree during a genial than during an ungenial summer; the southern slopes of a hill are more verdant and flowery than those of its northern side; some plants luxuriate in the sea-breeze which would be death to others; and the leafiest side of a tree is ever that which is most accessible to the

open sunshine. Again: plants that grow in localities marked by sudden extremes of heat and cold are always more variable in stature, habit, and foliage, than those which flourish under the steadier influences of a genial

* The capacity of the atmosphere for heat decreases with its density, and this density decreases from the level of the ocean upwards.

climate; and thus we can judge of the climate of a newlydiscovered country, as well as of the conditions that prevailed and affected plant-life during the deposition of a rock-formation, which took place thousands of ages ago. Still further, and apparently altogether independent of climate certain families are restricted to certain regions, beyond which, and under the present arrangements of sea and land, they naturally never pass; and thus it is that the Cape of Good Hope rejoices in its pelargoniums and geraniums; China in its teas and camelias; Australia in its eucalypti and casuarina; the Spanish peninsula in its ever-green oaks; and the pampas of South America in their gigantic thistles and clover, to the almost total exclusion of other species. Descending from family regions to the narrower provinces of genera and species, we find some limited to a single valley, to a solitary island, or, it may be, to some particular mountain-slope which, as far as science can perceive, enjoys no external influence that is not equally shared by the other slopes that surround it.

Beyond all these distinctions there is the difference of KIND—a difference for which science can assign no reason, save that it has pleased the Creator so to create them. Why, for instance, does the moss differ from the rush, the rush from the reed, the reed from the willow, the willow from the birch, the birch from the pine, or the pine from the palm? The oak and the ash grow side by side in the same forest, and yet they are, in the language of naturalists, specifically and generically distinct; the daisy and wild clover spring from the same soil, and interweave their rootlets to form the same turf, and yet they have no feature or quality in common. That these are facts, the eye of the passing observer may readily perceive; the reason why, man may never know. It is of little avail to talk of the plasticity of the vegetable organism under the force of

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