It only serves to make the matter less intelligible, that there are found in Secondary strata some few relics of birds with decidedly saurian characteristics,[198] as the Hesperornis and Ichthyornis in the Chalk, and the Archæopteryx, most ancient of fowls, lower still, in the Oolite. All these creatures have lizard-like heads and teeth; the Archæopteryx in addition has decidedly reptilian characters connected with its wings and tail. But none of them throw the slightest light upon the point we are now considering.[{172}] In the case of all, the problem of flight has been completely solved. Their wings are no rudimentary structures half way between legs and wings, but as finished productions as those of to-day. As Professor Huxley acknowledges, if the skeletons of Hesperornis and Icthyornis had been found without their skulls, they would probably have been classed without more ado amongst existing birds. The latter "has, [he tells us,] strong wings, and no doubt possessed corresponding powers of flight." The wings of Hesperornis, he says, resemble those of our divers and grebes, and were probably used, like theirs, chiefly for swimming.[199] As for the Archæopteryx, its reptilian features notwithstanding, it is a perfectly-appointed bird. As Sir Richard Owen testifies,[200] its wing, despite the peculiarities mentioned, is completely developed as to all essentials. Nor does even this member furnish the creature with its most bird-like characteristics,—but the keeled breast-bone, so intimately connected with the requirements of flight,—and, still more markedly, the feet. Professor Huxley writes: "The feet are not only altogether bird-like, but have the special character of the feet of perching birds; while the body had a clothing of true feathers."[{173}]
Thus, to whatever these Saurian birds may testify,—and the extreme importance of their evidence none will question—they no more serve to bridge the gulf between reptiles and birds, than a group of volcanic islets like the Azores bridges the Atlantic, for they supply no vestige of a continuous way from one term to the other. Rather, they do but enhance the mystery of the transformation, to the manner of which, despite their composite features, they furnish no clue.
All such difficulties are enormously aggravated by a consideration which, obvious as it is, seems seldom to be considered. The arguments we commonly hear appear to imply that one parent is sufficient to secure the transmission of a beneficial variation to the next generation. But, of course, the parent requires a mate, and unless this mate has chanced to hit on the same line of variation, it cannot be supposed that it will be transmitted. Seeing, however, the exceeding minuteness of these variations in each instance, they can avail nothing to bring together the right mates to perpetuate them. Two reptiles, for instance, are not the more likely to pair because their fore limbs have taken the first faint and distant step towards becoming wings, while in the vegetable kingdom, notwithstanding Erasmus Darwin's Loves of the Plants, the idea of any choice of partners is still more grotesque. The allotment of mates must therefore be left to Chance; and the results will follow the ordinary laws of probability. Accordingly, if we suppose so large a[{174}] proportion as five per cent., or one in twenty, of any species to possess an advantageous variation,—only one in twenty of the individuals thus favoured will secure a similarly favoured mate,—for each will have nineteen wrong selections offered to him or her, for one right one. Only one pair in four hundred will therefore transmit the variation to five per cent. of their offspring, or one in eight thousand of the species, and of these only one pair in a-hundred-and-sixty-thousand will make an advantageous match. Such is the inevitable consequence of leaving any definite result to Chance: and here it is that Natural Selection is found to betray the most fatal of all its deficiencies; for, whatever its advocates may say, it is Chance and Chance alone upon which it relies. Just because man can and does select the proper mates, is he able to produce by breeding the results to which Mr. Darwin appeals as evidence, that Nature having no such power of selection, must be able to produce results of which man cannot even dream.[201]
Natural Selection is in truth no selection at all, that is just its weak point, which the title conferred upon it serves to hide. What are called its products owe no more to it than Wellington owed his generalship to the bullets which did not hit him at Seringapatam. If they are not determined to a particular development they can attain it only by Chance.
Of Chance, enough has already been said. It is,[{175}] however, worth our while to observe how constantly to the last Mr. Darwin was haunted by the consciousness that this was in reality the factor upon which his system must depend, and that it could not possibly account for much that he came across in nature. If, as he confessed, the sight of a peacock's tail-feather made him sick, it was just because its elaborate beauty, to which no commensurate advantage can be supposed to attach, forbade the notion that his theory could account for it. So, of another still more marvellous instance in which Nature exhibits artistic power, namely the ball-and-socket ornament on the wings of the Argus pheasant, he writes:[202]
No one, I presume, will attribute this shading, which has excited the admiration of many experienced artists, to chance—to the fortuitous concourse of atoms of colouring matter. That these ornaments should have been formed through the selection of many successive variations, not one of which was originally intended to produce the ball-and-socket effect, seems as incredible as that one of Raphael's Madonnas should have been formed by the selection of chance daubs of paints made by a long succession of young artists, not one of whom intended at first to draw the human figure.
Nevertheless, Mr. Darwin proceeds to argue at considerable length that an explanation consistent with his theory is favoured by the occurrence on the same wings of designs exhibiting every stage of gradation from a mere spot to the finished ball-and-socket ocellus; in the same way as the tail feathers of a peacock advance from a mere sketch to the completed design. It is not easy, however, to understand in what way this is supposed to solve the difficulty and not vastly to increase it. That a finished artistic effect should be fortuitously produced at all would be incredible enough. That it should be worked up by Chance through a series of processes, each doing something towards its completion, is surely not less, but far more inconceivable.
In such a mode of explanation, however, is exemplified a feature which must not be forgotten in discussing Darwinism,—namely the fatal facility with which seeming arguments can be procured on its behalf. As Mr. Mivart well remarks:[203] "The Darwinian theory has the great advantage of only needing for its support the suggestion of some possible utility, actual or ancestral, in each case—no difficult task for an ingenious, patient, and accomplished thinker." And our North British Reviewer makes a similar comment: "The believer who is at liberty to invent any imaginary circumstances, will very generally be able to conceive some series of transmutations answering his wants."