Dicotyledons furnish evidence of especial value. On account of their higher organization, they are easily distinguished from both Monocotyledons and Gymnosperms; and they present features which clearly differentiate them amongst themselves. They did not make their entry till after a long interval—and their remains are therefore to be found in strata comparatively recent and better known to us than those of the older rocks. It is in the Chalk, the newest of the Secondary or Mesozoic formations, that they first exhibit themselves, and they do it in the same fashion as their predecessors.{221}

When the Dicotyledons appear in the upper cretaceous beds, representatives of the three great groups [Apetalæ, Monopetalæ, Polypetalæ] appear together in the same deposit. Moreover, these divisions are represented, not by generalized types, but by differentiated forms, which, during the intervening epochs, have not developed even into higher generic groups.

And, here again, there is no vestige of intermediate species, linking dicotyledonous plants with other types.

Nor, on the same authority, is this all.

We have already seen something of an example which illustrates this point in a remarkable manner,—that of Salix polaris, the willow which has so obstinately preserved its specific identity amid great stress of circumstances. It belongs to a very variable genus—one in which if anywhere evidence of genetic development might be looked for. Yet it is found that since a period prior to the great Ice Age, or Glacial epoch, it has remained absolutely unchanged. At such a rate, we cannot but ask, how long would Evolution take to get back to the generalized type-form, or common ancestor, of the genus Salix, and then to that of the Order Salicineae, which includes poplars as well as willows. "The Ordinal form, if it ever existed, must necessarily be much older than the period of the upper Cretaceous rocks, that is than the period to which the earliest known Dicotyledons belong."

And it is obvious that when we had got back to the parental stock of the willow tribe, we should still, as evolutionists, be separated by a gulf still vastly greater from the common ancestor of all{223} Dicotyledons, of oaks, apple-trees, primroses, and daisies no less than of willows and poplars.

The significance of all these various facts is thus summed up:

So much for the vegetable world. As for the animal, although the number and complexity of its divisions makes it less easy to present so complete a sketch in these moderate limits, the features of its history are very similar. As Sir J. W. Dawson recounts it:[253]{224}

{225}

In the Cambrian age, we obtain a vast and varied accession of living things, which appear at once, as if by a sudden and simultaneous production of many kinds of animals. Here we find evidence that the sea swarmed with creatures near akin to those which still inhabit it, and nearly as varied.... Had we been able to drop our dredge into the Cambrian or Silurian ocean, we should have brought up representatives of all the leading types of invertebrate life that exist in the modern seas—different, it is true, in details of structure from those now existing, but constructed on the same principles, and filling the same places in nature.

In the latter half of the Palæozoic we find a number of higher forms breaking upon us with the same apparent suddenness as in the case of the early Cambrian animals. Fishes appear, and soon abound in a great variety of species, representing types of no mean rank, but, singularly enough, belonging in many cases to groups now very rare; while the commoner tribes of modern fish do not appear. On the land, Batrachian Reptiles now abound, some of them very high in the sub-class to which they belong. Scorpions, spiders, insects, and millipedes appear as well as land-snails: and this not in one locality only, but over the whole northern hemisphere.... Nor do they show any signs of an unformed or imperfect state.... The compound eyes and filmy wings of insects, the teeth, bones, and scales of batrachians and fishes; all are as perfectly finished, and many quite as complex and elegant, as the animals of the present day.

This wonderful Palæozoic age was, however, but a temporary state of the earth. It passed away, and was{226} replaced by the Mesozoic, emphatically the age of Reptiles, when animals of that type attained to colossal magnitude, to variety of function and structure, to diversity of habitat in sea and on land, altogether unexampled in their degraded descendants of modern times.... Strangely enough, with these reptilian lords appeared a few small and lowly mammals, forerunners of the coming age.[254] Birds also made their appearance.

The Kainozoic, or Tertiary, is the age of Mammals and of Man. In it the great reptilian tyrants of the Mesozoic disappear, and are replaced on land and sea by mammals or beasts of the same orders with those now living, though differing as to genera and species. So greatly indeed did mammalian life abound in this period that in the middle part of the Tertiary most of the leading groups were represented by more numerous species than at present, while many types then existing{227}

DIAGRAM ILLUSTRATING THE PROGRESS OF ORGANIC DEVELOPMENT. In the above Diagram the progress of Organic Development, as manifested in higher and higher types, is indicated by the increasing divergence of new forms from primitive simplicity of structure, represented by the medium line separating the vegetable and animal kingdoms. The Supposed line of continuous Evolution, indicates the gradual course which should be taken by Development, on Darwinian or Spencerian principles, by accumulation of minute differences in successive generations, as contrasted with the abrupt and simultaneous appearance of highly differentiated types, as spoken of by palæontologists. [To face page 227.]

It must be sufficient to quote one other remark:[255]

Having given a tabular view of Geological periods and Life-epochs, similar to those presented above, our author remarks:[256]

{228}

And here may be noticed an observation made amongst others by the Comte de Saporta[257] on the remarkable parallelism of Animal and Vegetable development. After a period in which these kingdoms were respectively represented by aquatic Algæ and Protozoa, land animals and land plants appear to have come in much at the same epoch; and afterwards dicotyledonous plants immediately preceded the advent of mammals.

Mr. Mivart is of like mind with the others we have heard. "The mass of palæontological evidence," he writes,[258] "is indeed overwhelmingly against minute and gradual modification." He points out, with the North British Reviewer so frequently quoted, that had the later forms of life descended from the earlier, through such a series of imperceptible gradations as is imagined, the probability would be that no two fossil specimens would be exactly alike, whereas in fact numbers are found of certain particular patterns, and none whatever between them, fossil animals and plants falling naturally into species, genera, families, and other categories just like those of the present day.

It is this total absence of graduated series, linking different forms together, that is the great and fundamental difficulty in the way of genetic evolution. Yet this seems very seldom to be realized, and it seems constantly to be assumed that in order to establish the genetic continuity of two creatures{229} no more is required than to discover another standing more or less between them. Thus in the most famous of all instances, how often do we hear of "the missing link" between man and ape,—as though should a generalized form be disclosed, which might be considered a common ancestor, the question of man's simian origin would be finally settled. In the same way, as we have seen, the existence of birds with reptilian features, is taken by some as conclusive proof that birds and reptiles have descended from one stock. But what is most imperatively wanted, is persistently wanting,—namely some evidence of a series in which one form passes to another, as in a dissolving view. And yet, genetic evolutionists must suppose such series to have been the universal rule throughout the whole course of life on earth.

In some particular instances the absence of any trace of intermediate forms is especially significant. The tribe of Bats, for instance, is a very singular one. The wings, in which form the fore-limbs are specialized, represent the same elements as our own{230} hands; and other modifications of the same members have produced the paws of cats and dogs, the hoofs of horses and cattle, and the flippers of whales and porpoises,—to mention no others. What countless hosts of the Bat's ancestors must have lived and died while by accumulation of minute differences the primitive generalized limb whence all these diverse forms originated, was being turned into a wing capable of flight. Yet of all these no vestige is to be discovered. "Whenever the remains of bats have been found," says Mr. Mivart,[260] "they have presented the exact type of existing forms." The same, he tells us, holds good of other flying creatures—birds and pterodactyles—(or flying lizards—now wholly extinct). No trace of any of these is forthcoming while their wings were in the making. "Yet had such a slow mode of origin as Darwinians [and genetic evolutionists generally] contend for, operated exclusively in all cases, it is absolutely incredible that bats, birds, and pterodactyles should have left the remains they have, and yet not a single relic be preserved in any one instance of any of these different forms of wing in their incipient and relatively imperfect functional condition!"

There are other creatures which stand in solitary isolation, with no fragments of a bridge to connect them with the general body. Such is the rattlesnake's family, whose pedigree, Mr. Mivart declares,[261] we cannot even imagine—"The ancestors{231} of the rattlesnake are beyond our mental vision."

Professor W. C. Williamson likewise remarks[263] on these lacunæ which persistently occur at crucial points:

He presently adds:

{233}

And elsewhere Professor Williamson reiterates the same idea:[264]

In the record of fossil fishes he finds some features which are particularly hard to harmonize with any theory of genetic evolution.[265] Amongst the very earliest representatives of this class, even in the upper Silurian, are found remains of sharks, in his opinion the highest order of fish, and in the Devonian and Carboniferous above, of Ganoids armour clad, like the sturgeon. But nowhere below the Chalk do we find a single scale of Cycloids or Ctenoids, which in regard alike of the scales themselves, of the nervous system and of the reproductive organs, are much below the sharks, and not above the Ganoids. To complicate matters still more, however, the skeleton of Cycloids and Ctenoids is more highly organized than that of the others, and it is thus equally impossible to describe them as progressive or as retrogressive types.[266]

Over and above this absence of intermediate or link forms, the witnesses who have been cited insist{234} on the fact that those earliest found are not simple or generalized representatives of their respective types, as the theory of genetic evolution requires them to be, but are as perfectly finished and specialized as those appearing in later ages. To their testimony on this point may be added that of Professor Huxley, who while frankly confessing that he would be glad enough to find evidence in favour of such progressive modification, was constrained by his love of scientific truth to bear witness as follows:[267]

So again he declared at a later period[268] summarizing what he had said previously:

He went on, however, to say, on this latter occasion, that discoveries made in the interval afforded much ground for softening "the Brutus-like severity" which eight years before he had exhibited in this regard, by disclosing such evidence as he had declared to be lacking. From the samples, however, which he produced, it does not appear that this fresh testimony comes to very much; and in view of the observations with which he accompanied the exposition, it would seem that in only one instance did it appear to himself thoroughly satisfactory.

Of this famous instance we have already heard, and since it will be examined at length in the following chapter, we will not dwell further upon it here.

So obvious indeed is this deficiency for evolutionary requirements of the Geological record, that Professor Haeckel attempts to supply the want by boldly interpolating a number of periods during which the metamorphoses occurred, but of which no record was left. He assumes that between the epochs of depression, when fossils were deposited beneath the water, there were other epochs of elevation when the land was dry and no deposits could occur, and he supposes that the abrupt changes of flora and fauna exhibited by successive formations, are due to the lapse of time of which we have no organic record in what he styles these "Ante-periods."

As to this summary mode of loosing the Gordian knot, it will be sufficient to quote Professor Huxley's verdict: "I confess this is wholly incredible to me."[271] And although in his favourable review of Haeckel's book[272] he showed himself far more tolerant of{237} gratuitous speculations, than his utterances on other occasions might have led us to expect, upon this point he declared: "I fundamentally and entirely disagree with Professor Haeckel."

We may sum up the testimonies of which the above are representative in the words of two authorities by no means hostile to Evolution. M. Edmond Perrier,[273] having shewn how this theory is suggested by the successive developments of type, and how the phenomena of organic life seem to harmonize with it, thus continues:

And in his Presidential address to the Linnean Society, May 24, 1902, Professor S. H. Vines thus expressed himself as to the genealogical table of organic life, which ever since the doctrine of Evolution was accepted, it has been sought to construct:

But it is precisely such an inherent tendency of organic life to develop on predetermined lines, which Darwinians and other advocates of Evolution by the agency of physical forces alone, vehemently repudiate as fatal to their whole system.

{239}

XVII

Remarkably enough, at almost the same period[274] Professor Huxley concluded a discussion of palæontological evidence with a precisely contrary pronouncement—"The whole evidence is in favour of Evolution, and there is none against it." On other occasions, also, he distinctly maintained that it is just this line of enquiry which conclusively establishes Evolution as no longer a theory, but an historical fact. To such a conclusion, he tells us,[275] "an acute and critical-minded investigator is led by the facts of palæontology;"—and, again, "If the doctrine of Evolution had not existed, palæontologists must have invented it, so irresistibly is it forced upon the mind by the study of the remains of the Tertiary mammalia."

Such declarations clearly challenge consideration,{240} especially when it is remembered how strict were the views which Professor Huxley professed as to the necessity of proofs for our beliefs,—"that it is wrong for a man to say he is certain of the objective truth of any proposition unless he can produce evidence which logically justifies that certainty."[276]

We therefore turn naturally to his lectures on Evolution, wherein he treats the palæontological argument ex professo, and we find that his verdict is based upon a few selected instances, such as that of the reptilian birds already mentioned, which he considers favourable to Evolution, and one which he terms demonstrative,—namely that of the Horse. This he treats in some detail; in regard of it he delivers the positive judgment which we have just heard, and it therefore in a special manner demands our attention.

As furnishing evidence for the history of the horse, two features are of special importance, his limbs, and his teeth. Of these we may confine our attention to the former, as being, at once, sufficient for our purpose, and within the scope of ordinary observation.

The horse family, or Equidae, belong to the tribe of Ungulates, or hoofed animals, some points of whose anatomy require to be considered in relation to our own.

Taking first the fore-limbs. What we call the "knee" of a horse is in reality the wrist,—the true{241} knee, or rather elbow, being what we call the "shoulder." Below the knee comes the "cannon bone," corresponding to the middle bone of the hand, and below it the "pastern," "coronary," and "coffin" bones, representing the joints of the solitary middle-finger, while the hoof is its greatly enlarged and thickened nail. Similarly, in the hind-limbs; the "hock" is veritably the ankle, and again the lateral digits are suppressed, the middle toe alone remaining.

It thus appears that an Ungulate such as the horse, is an extreme modification of the general Mammalian plan, his members being highly specialized for a certain kind of work. His leg and hoof, as the theory of genetic Evolution declares, have been gradually fashioned to their present shape from an original limb in the common Mammalian ancestor, which by other modifications has equally produced the totally different members possessed by other mammals.

That the horse is descended from a race bearing more than one digit on each extremity, seems to be indicated by the splint-bones which are found on the cannon-bone of both fore and hind legs, and which represent the second and fourth finger and toe, and also by recorded occurrences of polydactyle horses, one of which has a distinguished place in history as Julius Cæsar's charger.[277]{242}

That the animal as we now know him is the lineal descendant of various other ungulates, in whom the digits were gradually reduced from the normal number of five, to their present solitary representative, Professor Huxley and other Evolutionists hold to be demonstrated by the discovery in due succession of various equine specimens, in which this diminution is gradually exhibited.

The remains of these animals are all found in Tertiary strata, of which, it will be remembered, there are three great divisions, the Eocene, Miocene, and Pliocene, the first named being the most ancient, and the last the most recent.

The genus Equus, or at least our modern horse, Equus caballus, can be traced no further back than the Post-tertiary period. The succession of forms leading up thither commences at the bottom of the Eocene, and extends to the upper Pliocene.

Following Professor Huxley's guidance, we trace the pedigree downwards, thus:

Here, when the lecture which we are considering was delivered, the series terminated:—and upon the facts as above given Professor Huxley thus commented:

Finally he was able to add in a note that since the delivery of the lecture, Professor Marsh had discovered a new genus of Equine Mammals, Eohippus, corresponding very nearly to his description of what might first be looked for. "This," adds Professor Huxley, "is what I mean by demonstrative evidence of Evolution.... In fact, the whole evidence is in favour of Evolution, and there is none against it."

That these facts are indeed most remarkable and deserving of all attention, cannot be questioned. But before we can agree that they are conclusive and demonstrative in Professor Huxley's sense a good many considerations require to be carefully weighed.

(i.) It is obvious, in the first place, that here as in all other instances which we have seen, the one thing is lacking which is really wanted in order to prove Evolution, namely evidence of one species gradually shading off into another. The creatures of which we have heard, are each isolated from the rest, and indeed very much isolated, for each belongs to a different genus,[279] which shows that the differences{245} between them are substantial. They are, in fact, farther apart from one another, than the zebra or the donkey from the horse, for both of these are classed in the genus equus,—or than the Bengal tiger is from the domestic pussy-cat, both belonging to the genus felis.

These various ungulate forms thus stand a long way from one another, and if they were once connected together by a bridge, or rather a causeway, we ought certainly to find some traces of it, and not always of those particular types which require to be united. If we suppose the very distinct species actually known to have been the piers of such a bridge, yet what has become of the arches? Till some vestiges of these be found, or, at least, some positive evidence that arches there actually were, can it be said that the story of the fossil equidae furnishes convincing testimony on behalf of the supposed evolution? Affinities these various forms undoubtedly exhibit: it has yet to be shown that affinities necessarily imply descent.

There is, however, something even more remarkable. We have seen that Professor Huxley prognosticated beforehand the discovery of Eohippus, and specified pretty nearly the features it would be found to present. In the same way, Professor Marsh[280] anticipates and describes a still more remote ancestral form, for which, though it has not yet been{246} found, he has provided an appellation, Hippops. But if either Professor really believes in Evolution, why does he take for granted that we shall chance upon one particular form, standing like a solitary outpost by itself, and not upon any other trace of the stream of life whereof it was but one transient phase? Such predictions may be evidence that the occurrence of these progressive forms is regulated by something analogous to Bode's Law of interplanetary distances, and that their discovery may be looked for at certain intervals. But the very fact that their actual position can be so accurately specified serves to show that it is very definitely fixed.

(ii.) Moreover, a very grave difficulty at once suggests itself, of which Professor Huxley makes no mention. The horse as we now have him, Equus caballus, is a native of the Old World, and has been introduced to America only since the time of Columbus. There had, it is true, been horses in America previously,—belonging to the genus Equus, perhaps even to the species caballus,—they had, however, been long extinct, and no memory of them remained. But, as will be noticed, the pedigree given by Professor Huxley consists almost entirely of American animals, to which category belong all whose names terminate in -hippus, and these cannot with any reason be assigned as progenitors to the European horse. As Sir J. W. Dawson observes:[281]{247}

(iii.) Even apart from this fundamental difficulty, there is much diversity as to the precise genealogy. We may compare together the lines of ancestry favoured—(1) by Professor Huxley, (2) In a case exhibited in our Museum of Natural History to illustrate the subject, (3) By Mr. Mivart,[282] (4) By{248} Mr. Lydekker,[283] (5) In The Evolution of the Horse, a pamphlet issued, January, 1903, by the American Museum. This last gives the very latest version of the pedigree, but, naturally, of the American Horse alone.

It will be observed, that whereas Hipparion is disallowed by Professor Huxley as not being in the direct line of descent, in all the other genealogies he appears as the immediate ancestor of Equus. Also that in all these tables, Old World and New World forms are used indifferently to supply progenitors for the same successor. Also that there is no agreement at all as to the earlier ancestry. It would likewise appear that even the existence of Eohippus himself is not beyond question, for in our Museum galleries and guide-book his name always has a note of interrogation appended. The American authorities give an anticipatory sketch of the limbs of the ancestor which still remains to be discovered.

There is something even more remarkable.{249}