Whether modern geologists are right or wrong as to the gradual nature of these mighty changes, no one can doubt that the time they occupied must have been very great indeed. Who can say how great? There is nothing to show that the elevation of any of these mountain-ranges was continuous. There may have been enormous periods of rest, or there may have been (what we know to have been in the case of the British Isles) alternating periods of elevation and depression. And what says Darwin to this? Why, that just the very period during which most variation occurs is also that of which there is no record. Extinction will be more rife during subsidence; but preservation will not be effected while the land is rising. No new strata wherein fossils can be embedded are formed on dry land that remains unchanged. "Forests may be as dense and lofty as those of Brazil, and may swarm with quadrupeds, birds, and insects, yet at the end of thousands of years one layer of black mould, a few inches thick, may be the sole representative of those myriads of trees, leaves, flowers, and fruits, those innumerable bones and skeletons of birds, quadrupeds, and reptiles which tenanted the fertile region. Should this land be at length submerged, the waves of the sea may wash away in a few hours the scanty covering of mould, and it may merely impart a darker shade of colour to the next stratum of marl, sand, or other matter newly thrown down."1 Yes, even where remains have been preserved in the order of their extinction, these, to be discovered, must be upheaved. But if this process be very gradual, they would be removed by denudation as soon as they came to light. The exposure of metamorphic schists and plutonic rocks on an enormous scale in some parts of the world-(Humboldt) describes the granitic region of the Parime as at least nineteen times as large as Switzerland)-indicate such an amount of erosion that Darwin may well say: "It is probable

whole formations have been completely denuded, with not a wreck left behind."

A chapter of instances might easily be added to the scraps here collected. Lyell gives many reasons, such as the perishable nature of organic remains (and we all know "your water is a sore decayer of your whoreson dead body"), why we may seek in vain for relics. Besides, geology is in swaddling-clothes. One need scarcely to have lived half a century to remember the dogmatic assertions of such men as Sedgwick, Murchison, and Agassiz, which recent lights have completely falsified. The discovery of monkeys in the Miocene stage was never dreamed of by Cuvier. Moreover, connecting links, as we have seen, are no longer altogether wanting. The affinity between birds and reptiles is established by the compsognathus and the archæopteryx; between reptiles and fishes by the archægosaurus of the coal measures; between the orohippus of the Eocene and the true horse by the nicest of gradations; between bears and wolves; between hyænas and civets; between giraffes and deer; and even between the pig and the camel.

With reference to those cases of geographical distribution which the theory of descent seems inadequate to account for, what, we must inquire, were the possible means of dispersion in bygone times? This inquiry should be prefaced by the remark that, Darwin and almost every one of his followers believe in what is called specific centres," i.e., “that each species has proceeded from a single birthplace." Only upon this hypothesis, they say, can we explain the fact that certain distinct families are confined to different quarters of the globe. They are bound therefore to explain these apparent anomalies without violating the principle of "centres of creation."

Darwin declines to avail himself exclusively of geographical oscillations. He does not believe that the continuity, within recent times, of existing continents and

islands can ever be demonstrated. Besides this means of dispersal, however, there were others which would equally serve the purpose. Some of the interchanges amongst flora and fauna of what are now warm and cold regions— such as reindeer in the south of France and the ichthyosaurus in the Arctic regions-are explained by extreme variations of climate hereafter to be considered. We know that vegetation similar to that of Northern Europe once extended to the Arctic regions, "and probably reached the pole."1 Alluding to the bones and teeth of the ancient elephants hidden amongst the gnarled roots of the "Cromer forest," Dr. Huxley says, in his picturesque way, "Sea-beasts, such as the walrus, now restricted to the extreme north, paddled about where birds had twittered among the topmost twigs of the fir- trees." Darwin mentions a crowd of instances which might be added to Mr. Mivart's list, all to the effect that forms characteristic of one part of the world are met with in another. And, what climate itself fails to explain may often be ascribed to the direct instrumentality of ice. In Pleistocene times, during the glacial epoch, floating ice would have transported not only plants but animals to parts of the world widely divided by oceans; just as bears and Arctic foxes, and even shipwrecked crews, are now occasionally carried for hundreds of miles upon icebergs. It was not the northern hemisphere alone that was subjected to these severities. Forbes found marks of the ice action in the furrowed rocks of the Cordillera from lat. 13° to 30° south, at a height of about 12,000 feet. "Further south on both sides of the continent, from lat. 40° to the southernmost extremity, we have the clearest evidence of former glacial action in numerous immense boulders transported far from their present source." 2

Still it must be owned, Mr. Mivart's centetes is an awkward interloper, to say nothing of his pleurodont lizard. 1 Lyell's Principles, &c., chap. xi.

2 Origin, &c., p. 335.

There are many reasons why the presence of these animals in Madagascar is peculiarly inappropriate. It is a long voyage, even on an iceberg, from Madagascar to the West Indies or South America. Yet changes in the disposition of sea and land would not help us here. We know "that the sea, even in post-tertiary times, covered the space now occupied by the Sahara, so that Africa was for vast periods surrounded by water on every side but the northeast, where it was connected by an isthmus with Asia."1 Clearly, the chances of a lizard from South America reaching Madagascar via this isthmus would be small. Then too, the Mozambique Channel, which separates Madagascar from the mainland, is 300 miles wide. Finally, owing to this circumstance, the indigenous fauna of Madagascar is so distinct as to form a zoological sub-province. There is one escape from the puzzle, so far as the small insectivorous quadruped goes, "it is supposed to have been taken in ships." 2 But this supposition will hardly avail for the pleurodont. Upon the whole, however, the Darwinians have, I think, the best of it. And we may pass to the next item in our catalogue.

The LIMITS-OF-VARIABILITY question is nothing but the old wrangle about the mutability of species, which, as before observed, lies at the root of the whole discussion. One test, always applied to this, was long thought to be decisive, viz., the sterility of hybrids. We can breed from varieties of the same species, but not from males and females of different species. At any rate, when distinct species do produce offspring, these hybrid offspring are (said to be) barren. Thus Nature, it is alleged, sets her limits to variation.

Now, sterility can no more be acquired by natural selection than barrenness can run in families. Darwin abandons the notion that it can be a byelaw of his theory. His answer virtually is: the allegation is not true, and if it were, it would not signify. "It cannot be maintained 1 Lyell's Principles, &c., vol. ii. p. 346.

2 Ibid.

that species, when intercrossed, are invariably sterile and varieties invariably fertile, or that sterility is a special endowment of creation."1 Instead of its being a special endowment, it is but a physical accident. "It is an incidental result of differences in the reproductive system of the parent species." 2 Which differences, says the selectionist, are products of gradual change in the descendants of a species,-accumulated differences, i.e., of varieties. It is absurd to argue that because the change finally reaches a point at which the varieties cease to interbreed, therefore these varieties which naturalists class as distinct species must be specially created.

Nearly all our experience in this matter is derived from domesticated or from captive animals. The test of domestication gives conflicting results; yet, in both ways I think, favourably to Darwinism. For example: wild

animals in captivity do not cross, and often will not interbreed with their own species. In a state of nature, the struggle for existence would suffice to prevent amalgamation. Again, "the domesticated descendants of species, which in their natural state would have been in some degree sterile, when crossed become perfectly fertile together." 3 And "with our domesticated animals the various races when crossed together are quite fertile; yet in many cases they are descended from two or more wild species." 4

In the "Origin of Species" we are furnished with instances of plants whose fertility is much increased by the pollen of other species. M. Quatrefages is quoted as stating that the hybrids of certain moths continued to breed for eight generations. Professor Häckel cites many cases of the fruitful hybrids of distinct species, "as, among several genera of butterflies. . . the family of carps, finches, poultry, dogs, cats, &c."5 The hare-rabbit, or

1 Origin, &c., p. 422.

Ibid., p. 235.

3 Animals and Plants under Domestication, vol. ii. p. 173.

4 Origin, &c., p. 240.

5 History of Creation, vol. i. p. 147.