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 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 acc.u.mulation 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 of the rattlesnake are beyond our mental vision."

But the number of forms [says the same author][262] represented by many individuals, yet by _no transitional ones_, is so great that only two or three can be selected as examples. Thus those remarkable fossil reptiles, the Icthyosauria and Plesiosauria, extended, through the secondary period, probably over the greater part of the globe. Yet no single transitional form has yet been met with in spite of the mult.i.tudinous individuals preserved. Again, with their modern representatives the Cetacea, one or two aberrant forms alone have been found, but no series of transitional ones indicating minutely the line of descent. This group, the whales, is a very marked one, and it is curious, on Darwinian principles, that so few instances tending to indicate its mode of origin should have presented themselves. Here, as in the bats, we might surely expect that some relics of unquestionably incipient stages of its development would have been left.

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

If [he writes] these generic types [of plants] first came before us in such clearly defined forms, when and where did the transitional states make their appearance? The extreme evolutionists constantly affirm of those who believe in special creation that they "habitually suppose the origination to occur in some region remote from human observation," and that "the conception survives only in connexion with imagined places where the order of organic phenomena is unknown." It is legitimate to retort upon them that they as habitually resort to "strata now covered by the sea"--to rocks "from which all traces of such fossils as they probably included have been obliterated by igneous action," and to mysterious "migrations from pre-existing continents to continents that were step by step emerging from the ocean." Unfortunately, so far as the vegetable kingdom is concerned, we have as yet failed to discover any traces of these mysterious strata or hypothetical continents in which the transitions from one plant-type to another were being brought about. The believers in special creations are not the only reasoners who have made free use of hypothetical possibilities.

He presently adds:

We have no evidence that unaided Nature has produced a single new type during the historic period. We can only conclude that the wonderful outburst of genetic activity which characterized the Tertiary age was due to some unknown factor, which then operated with an energy to which the earth was a stranger, both previously and subsequently. The knowledge of this factor is what we need in order to perfect our philosophy; and until we obtain that knowledge, many things must remain unaccounted for, so far as primeval vegetation is concerned.

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

I contend stoutly [he says] that, however numerous may be the facts that sustain the doctrine of evolution (and I am prepared to admit that there are many that do so in a remarkable manner), this unexplained outburst of new life demands the recognition of some factor not hitherto admitted into the calculations of the evolutionist school.

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 cla.s.s, 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 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]

The only safe and unquestionable testimony we can procure--positive evidence--fails to demonstrate any sort of progressive modification towards a less embryonic, or less generalized type, in a great many groups of animals of long-continued geological existence. In these groups there is abundant evidence of variation--none of what is generally understood as progression; and if the known geological record is to be regarded as even any considerable fragment of the whole, it is inconceivable that any theory of a necessarily progressive development can stand, for the numerous orders and families cited afford no trace of such a process.

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

In answer to the question, What does an impartial survey of the positively ascertained truths of palaeontology testify in relation to the common doctrines of progressive modification?... I reply: It negatives these doctrines; for it either shows us no evidence of such modification, or demonstrates such modification as has occurred to have been very slight; and as to the nature of that modification, it yields no evidence whatsoever that the earliest members of a long-existing group were more generalized in structure than the later ones.

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.

Every fossil [he said][269] which takes an intermediate place between forms of life already known, may be said, so far as it is intermediate, to be evidence in favour of Evolution, inasmuch as it shows a possible road by which Evolution may have taken place. But the mere discovery of such a form does not, in itself, prove that Evolution took place by and through it, nor does it const.i.tute more than presumptive evidence in favour of Evolution in general.

It is easy[270] to acc.u.mulate probabilities--hard to make out some particular case in such a way that it will stand rigorous criticism. After much search, however, I think that such a case is to be made out in favour of the pedigree of the Horse.

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 a.s.sumes 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 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:

Unfortunately, when we descend to details, such palaeontological gaps present themselves that every sort of objection is possible.

The chain which morphology has allowed us to piece together is continually snapped when we essay to travel back into the past....

The art of distinguishing realities from phantoms of the imagination is what has made modern science so great and so mighty.

She is strong enough to win honour by avowing ignorance, and because men see her always determined to speak the truth, they gradually realize that she is not dangerous.

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:

Though here and there fragments of the mosaic seem to have been successfully pieced together, the main outlines, even, of the great picture are as yet but dimly discernible.

The fact that organic Evolution should have proceeded so far as it has within such limits of time as may reasonably be allowed, admits, to my mind, of no other interpretation than that variation is not indeterminate, but, as Lamarck and Nageli have urged, there must exist in living matter a certain inherent tendency or bias in favour of variation in the higher direction. It is this tendency or bias that I venture to regard as the primordial factor.

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.

[Since Professor Williamson wrote, the opinion has been adopted that for the very reason which induced him to place the Sharks above the _Cycloids_ and _Ctenoids_, their relative positions should be reversed. The Sharks being a more "generalized" type, with features more akin to those of land-dwelling reptiles, and the others more "specialized" for purely aquatic conditions, the latter, it is argued, are a higher evolutionary product. As a necessary corollary it is a.s.sumed that vertebrate life originated, not, as had been supposed, in the sea, but in swamps or lagoons on the sh.o.r.e-line. It must, however, remain a question how far the facility with which theories can thus be modified according to requirements, is calculated to inspire confidence in them.]

XVII

"AUDI ALTERAM PARTEM"

We have heard Mr. Carruthers' declaration, based upon his survey of palaeontological botany, "The whole evidence is against Evolution, and there is none in favour of it."

Remarkably enough, at almost the same period[274] Professor Huxley concluded a discussion of palaeontological evidence with a precisely contrary p.r.o.nouncement--"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 palaeontology;"--and, again, "If the doctrine of Evolution had not existed, palaeontologists 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, 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 palaeontological 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 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 Caesar's charger.[277]

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:

Firstly, there is the true horse. Next we have the American Pliocene form, _Pliohippus_. In the conformation of its limbs it presents some very slight deviations from the ordinary horse. Then comes _Protohippus_, which represents the European _Hipparion_, having one large digit and two small ones on each foot.... But it is more valuable than _Hipparion_, for certain peculiarities tend to show that the latter is rather a member of a collateral branch, than a form in the direct line of succession. Next, in the backward order in time, is the _Miohippus_, [_Miocene_], which corresponds pretty nearly with the _Anchitherium_ of Europe. It presents three complete toes--one large median and two smaller lateral ones; and there is a rudiment of that digit which answers to the little finger of the human hand. The European record stops here: in the American Tertiaries, the series of ancestral equine forms is continued into the Eocene. An older Miocene form, _Mesohippus_, has three toes in front, with a large splint-like rudiment representing the little finger, and three toes behind. The _radius_ and _ulna_, _tibia_ and _fibula_,[278] are distinct. Most important of all is the _Orohippus_, from the Eocene. Here we find four complete toes on the front limb, three toes on the hind-limb, a well developed _ulna_, a well developed _fibula_.

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

Thus, it has become evident that, so far as our present knowledge extends, the history of the horse-type is exactly and precisely that which could have been predicted from a knowledge of the principles of Evolution. And the knowledge we now possess justifies us completely in the antic.i.p.ation, that when the still lower Eocene deposits, and those which belong to the Cretaceous Epoch have yielded up their remains, we shall find, first, a form with four complete toes and a rudiment of the innermost or first digit in front, with probably a rudiment of the fifth digit in the hind foot; while, in still older forms, the series of the digits will be more and more complete, until we come to the five-toed animals, in which, if the doctrine of Evolution is well founded, the whole series must have taken its origin.

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."