blue pigments were potentially there already; the insects' part was only to seize upon and favour them whenever special circumstances happened to bring them out into visible. actuality.

XXII.

THE FALL OF THE YEAR.

Up on the downs to-day the view is dreary and gloomy enough. A grey mist hangs over the horizon to seaward, while inland the hollow combes and rounded shoulders of the distant chalk range hardly stand out at all through the foggy air. Sunlight throws up their varied contour with splendid perspective depths of black shadow; but in dull wintry weather like this, the outline merges into a single, unbroken leaden-blue line against the white background of the sky. There can be no denying that chill October is really upon us. Yet even now a few patches of colour still remain-some golden heads of the

autumnal hawkbit on the open, some straggling bushes of the dwarf furze upon the glen-sides, and a mass of rich foxy-brown bracken among the tumbled and uneven. rockery of the undercliff. The season is not quite so far advanced here on the south coast as it was a few days since among the dry heather-clad hills and yellow autumn woods of North Wales. Every twenty miles southward tells at this season of the year, and so the passion-flowers are even now in blossom down here on the trellis-work of the cottage, with its southerly aspect, while the trees and creepers are fast growing leafless among the windy hills of the north and the midlands.

It was Buffon, that half-unconscious predecessor of our modern evolutionists, who first pointed out the true importance of these zones of climate, from pole to equator, in the history of life upon the earth. For Buffon, with all his contempt for systematic classification and for accurate scientific knowledge, was a man of that wide philosophic grasp and that

intuitive insight which are often more valuable after all than any amount of capacity for remembering dry detail; and he saw many points accordingly which were hidden from the wise and prudent artificial systematists of his time. Organic life, he remarked, must have begun at the Poles. For on the surface of an incandescent planet the Poles would be the first part to cool down sufficiently to allow of the conditions under which alone life becomes possible. This pregnant idea has since been fully developed by later naturalists. Not only is it true that life as a whole must have started at its first beginning from the Pole, but we now know that all fresh waves of fauna or flora must in like manner have set out from the self-same point, and occupied the earth by migration in circumpolar zones. Moreover, the great centre of all life was in all probability the North Pole alone, not the South; for since Mr. Wallace's luminous researches on the geographical distribution of animals, it has become almost

certain that our existing continents have been steadily growing up for a vast period. of time, and that our existing oceans have been oceans and nothing else ever since the aqueous vapour of our planet first condensed and cooled into water. Hence it follows that the South Pole has always been isolated in the midst of an enormous stretch of ocean, while the North Pole has always been the point from which the great land masses of Europe, Asia, Africa, and America have radiated southward. In both hemispheres we find the land widening out towards the North Pole, but tapering away towards the South; and we know that South America and South Africa were till recently isolated outliers of their respective continents, while Australia remains an isolated outlier of Asia to the present day. Thus, every great wave of animal or plant population must have set out always from the North Pole, must have spread southward in concentric circles, and must have but slowly reached the outlying