on this planet in times past, there is no instance of a highly organised form occurring low down in the geological series.[1] On the contrary, there is the best evidence to show that since the first dawn of life in the occurrence of the simplest organisms, until the meridian splendour of life as now we see it, gradual advance from the general to the special—from the low to the high, from the few and simple to the many and complex—has been the law of organic nature. And of course it is needless to say that this is precisely the law to which the process of descent with adaptive modification would of necessity give rise.

IV.

THE ARGUMENT FROM GEOGRAPHICAL DISTRIBUTION.

The argument from geology is the argument from the distribution of species in time. I will, therefore, next take the argument from the distribution of species in space—that is, the present geographical distribution of plants and animals. It is easy to see that this must be a most important argument, if we reflect that as the theory of descent with adaptive modification implies slow and gradual change of one species into another, and a still more slow and gradual change of one genus, family, or order into another genus, family, or order, we should expect on this theory that the organic types living on any given geographical area should be found to resemble or to differ from organic types living elsewhere, according as the area is connected or disconnected with other geographical areas. And this we find to be the case, as abundant evidence proves. For, to quote from Mr. Darwin, “barriers of any kind, or obstacles to free migration, are related in a close and important manner to the differences between the productions of various regions. We see this in the great difference in nearly all the terrestrial productions of the New and Old Worlds, excepting in the northern parts, where the land almost joins.... We see the same fact in the great difference between the inhabitants of Australia, Africa, and South America under the same latitude, for these countries are almost as much isolated from one another as possible. On each continent, also, we see the same fact; for on the opposite sides of lofty and continuous mountain ranges, of great deserts, and even of large rivers, we find different productions; though as mountain chains, deserts, &c., are not so impassable, or likely to have endured so long as the ocean-separated continents, the differences are very inferior in degree to those characteristic of distinct continents.” That is to say, the differences are usually confined to species and genera, whereas in the case of continents the differences extend to orders. Similarly in marine productions the same laws prevail—the species on the different sides of the American continent, for instance, being very distinct. Now, this law cannot be explained by any reasonable argument from design.

And still stronger does the present argument become when we look to the fossil species contained on different continents; for these fossil species invariably present the same characteristic stamp as the living species now flourishing on the same continents. Thus, in America we find fossils all presenting the characteristically American types of animals, in Australia the characteristically Australian types, and so on. That is to say, on every continent the dead species resemble the living species, as we may expect that they should, if they are all bound together by the ties of hereditary descent; while, if different continents are compared, the fossil species are as unlike as we have seen the living species to be.

Turning next to the case of oceanic islands, situated at some distance from a continent. In these cases the plants and animals found on the island, though very often differing from all other plants and animals in the world as regards their specific type, nevertheless in generic type resemble the plants and animals of the neighbouring continent. The inference clearly is, that the island has been stocked from the continent with these types—either by winds, currents, floating trees, or numerous other modes of transport—and that, after settling in the island, some of these imported types have retained their specific characters, while others have varied so as to become specific types peculiar to that island. The Galapagos Archipelago islands are particularly instructive in this connection; for while the whole group of islands lies at a distance of over five hundred miles from the shores of South America, the constituent islands are separated from one another by straits varying from twenty to thirty miles. Now, to quote from Darwin, “Each separate island of the Galapagos Archipelago is tenanted, and the fact is a marvellous one, by many distinct species; but these species are related to each other in a very much closer manner than to the inhabitants of the American continent.” That is to say, the American continent being some fifteen times the distance from these islands that they are from one another, emigration to them from the continent is of much more rare occurrence than emigration from one island to another; and therefore, as more time for variation is thus allowed, while the differences between the inhabitants of island and island are only specific, the differences between the inhabitants of the islands as a group and the inhabitants of the American continent are very often generic. I may mention, in passing, that it was upon discovering these relations in the case of the Galapagos Archipelago, and pondering upon them as “marvellous facts,” that Mr. Darwin was first led to entertain the idea that the doctrine of descent might be the grand truth for which the science of the nineteenth century was waiting.

The evidence from oceanic islands, however, is not yet exhausted; for in no part of the world is there an oceanic island more than a certain distance from a mainland in which any species of the large class of frogs, toads, and newts is to be found. Why is this? Simply because these animals, and their spawn, are quickly killed by contact with sea-water; and therefore frogs, toads, and newts have never been able to reach oceanic islands in a living state. Similarly in all oceanic islands situated more than three hundred miles from land, no species of the whole class of mammals is to be found, excepting species of the only order of mammals which can fly, viz., bats. And, as if to make the case still stronger, these forlornly created species of bats sometimes differ from all other bats in the world. But can we, as reasonable men, suppose that the Deity has chosen, without any apparent reason, never to create any frog, toad, newt, or mammal on any oceanic island, save only such species as are able to fly? Or, if we go so far as to say,—“There may have been some hidden reason why batrachians and quadrupeds should not have been created on oceanic islands,” I will adduce another very remarkable fact, viz., that on some of these islands there occur species of plants, the seeds of which are provided with numerous hooks adapted to catch the hair of moving quadrupeds, and so to become disseminated. But, as we have just seen, there are no quadrupeds in these islands to meet this case of adaptation; so that special creationists must resort to the almost impious hypothesis, that in these cases the Deity only carried out half His plan, in that while He made an elaborate provision for plants which depended for its efficiency on the presence of quadrupeds, He nevertheless, after all, neglected to place the quadrupeds in the same islands as the plants! Now, I submit that such abortive attempts at adaptation bring the thesis of the special creationists to a reductio ad absurdum; so that the only possible explanation before us is, that while the seeds of these plants were able to float to the islands, the quadrupeds were not able to swim.

Perhaps in sheer desperation, however, the special creationists will try to take refuge in the assumption that oceanic islands differ from continents in not having been the scenes of creative power, and have therefore depended on immigration for their inhabitants. But here again there is no standing-room; for we have already seen that oceanic islands are particularly rich in peculiar species which occur nowhere else in the world; so that, as a matter of fact, if the special creation theory is true, we must conclude that oceanic islands have been the theatres of extraordinary creative activity; although an exception has always been carefully made to the detriment of frogs, toads, newts, and mammals, save only such as are able to fly.

If space permitted, I might adduce several other highly instructive facts in this argument from geographical distribution; but I will content myself with mentioning only one other. When Mr. Wallace was at the Malay Archipelago, he observed that the quadrupeds inhabiting the various islands belonged to the same or to closely allied species. But he also observed that all the quadrupeds inhabiting the islands lying on one side of an imaginary sinuous line, differed widely from the quadrupeds inhabiting the islands lying on the other side of that line. Now, soundings showed that in exact correspondence with this imaginary sinuous line the sea was much deeper than in any other part of the Archipelago. Consequently, how beautiful is the explanation. We have only to suppose that at some previous time the sea bottom was raised sufficiently to unite all the islands on each side of the deep water into two great tracts of land, separated from one another by the deep strait of water. Each of these great tracts of land would then have had their own distinctive kinds of quadrupeds—just as the American quadrupeds are now distinct from the European; for the comparatively narrow strait between the then Malay continents would have offered as effectual a barrier to the migration of quadrupeds as does the Atlantic Ocean at the present day. Hence, when all the land slowly subsided so as to leave only its mountain chains and table lands standing above the surface in the form of islands, we now have the state of things which Mr. Wallace describes—viz., two large groups of islands with the quadrupeds on the one group differing widely from the quadrupeds on the other, while within the limits of the same group the quadrupeds inhabiting different islands all belong to the same or to closely allied species. On this highly interesting subject Darwin writes, “I have not as yet had time to follow up this subject in all quarters of the globe; but as far as I have gone the relation holds good. For instance, Britain is separated by a shallow channel from Europe, and the mammals are the same on both sides, and so it is with all the islands near the shores of America. The West Indian islands, on the other hand, stand on a deeply submerged bank nearly 1,000 fathoms in depth, and here we find American forms, but the species, and even the genera, are distinct. As the amount of modification which animals of all kinds undergo partly depends on lapse of time, and as the islands which are separated from each other or from the mainland by shallow channels are more likely to have been continuously united within a recent period than the islands separated by deeper channels, we can understand how it is that a relation exists between the depth of the sea separating two mammalian faunas, and the degree of their affinity—a relation which is quite inexplicable on the theory of independent acts of creation.”

So much, then, for the argument from geographical distribution—the many facts of crucial importance which it affords almost resembling so many experiments devised by Nature to prove the falsity of the special creation hypothesis. For now, let it in conclusion be observed, that there is no physiological reason why animals and plants of the different characters observed should inhabit different continents, islands, seas, and so forth. As Darwin observes, “there is hardly a climate or condition in the Old World which cannot be paralleled in the New ... and yet how widely different are their living productions.” And that it is not the suitability of organisms to the areas which they inhabit which has determined their creation upon those areas, is conclusively proved by the effects of the artificial transportation of species by man. For in such cases it frequently happens that the imported species thrives quite as well in its new as in its old home, and indeed often supplants the native species. As the Maoris say,—“As the white man's rat has driven away the native rat, so the European fly has driven away our fly, so the clover kills our fern, and so will the Maori himself disappear before the white man.”

Upon the whole then we are driven to the conclusion, that if the special creation theory is true, the various plants and animals have not been placed in the various habitats which they occupy with any reference to the suitability of these habitats to the organisations of these particular plants and animals. So that, considering all the evidence under the head of geographical distribution, I think we are driven to the yet further conclusion, that if the special creation theory is true, the only principle which appears to have been consistently followed in the geographical deposition of species, is the principle of so depositing them as in all cases to make it appear that the supposition of their having been thus deposited is not merely a highly dubious one, but one which, on the face of it, is conspicuously absurd.

V.

THE ARGUMENT FROM EMBRYOLOGY.

There is still another important line of evidence which we cannot afford to overlook; I mean the argument from embryology. To economise space, I shall not explain the considerations which obviously lead to the anticipation that, if the theory of descent by inheritance is true, the life history of the individual ought to constitute a sort of condensed epitome of the whole history of its descent. But taking this anticipation for granted, as it is fully realised by the facts of embryology, it follows that the