Such are not by any means the only instances in which the Darwinist can appeal to Nature for facts with which his theory well agrees, and which therefore so far furnish a persuasive argument in its favour; but these are perhaps the chief ones, and the best known, and may serve as representative of their class which it is impossible for us to examine in detail.
It now remains to enquire how far, from the point of view of Science, with which alone we are concerned, the Darwinian hypothesis can make good its claim to our acceptance. When we proceed accordingly to examine the grounds upon which it rests, it must be confessed that as we do so it becomes increasingly difficult to understand how such a theory has been able to obtain such wide acceptance, especially on the ground that scientific evidence is in its favour.
On the very threshold of any such enquiry lies a difficulty the gravity of which seems to be strangely[{161}] overlooked. Darwinism by its own confession knows nothing of Origins, not even of the Origin of Species itself. There must be life already existing before Natural Selection has anything to select; there must be eyes and honey-cells of some kind, before they can be improved; there must be Species, before one can be transformed into another. Is it not evident, however, that the cause—of whatever kind it may be—which brought any of these into being, must have something,—not to say everything,—to do with the capacities and potentialities by which its future history is conditioned? But this supreme and vital factor Mr. Darwin entirely eliminates from his calculation. In his system, the initiating force has no more to do with the subsequent career of its productions, than has the gas which lifts a balloon with the direction in which it travels. It is not, on his theory, as the impulse which, besides raising from earth an arrow or rifle bullet, directs it to a goal, but, on the contrary, an organism once launched on its course is left to be driven hither and thither and twisted into this form and that, as clouds are by the wind. For the variations through which transformations are wrought, Darwin could find no better epithet than "fortuitous," and it is laid down by his staunchest disciples that if such variations be predetermined towards certain results, there is an end of Darwinism.
It is not easy to understand how any theory can be deemed satisfactory which thus ignores the initial force, of whose existence and potency we have far clearer evidence than of any other.[{162}]
When we turn from its omissions to study Darwinism as it is, obviously, in the first place, still, more than forty years since it was given to the world, it remains only an hypothesis, based not upon observation or experiment but speculation. In no single instance, past or contemporary, is one species known to have originated from another. The fact upon which Mr. Darwin primarily relies is that of variation. Undoubtedly amongst both plants and animals the offspring are not mere slavish reproductions of their parents, as if cast in the same mould, but exhibit individual differences, working upon which in domesticated instances, man can by selection produce wonderful varieties, as has already been admitted. But, as M. de Quatrefages says,[191] this tells us no more than that species admit of variation; it does not prove that they are capable of transformation, which is the whole point. Certainly, such transformation has never within our knowledge been effected. No breeder or fancier has succeeded, or can hope to succeed, in producing a new species. Moreover, as was pointed out by a critic whose ability Mr. Darwin himself candidly acknowledged,[192] the range of variability as we find it in any species is strictly limited, and although at first it is easy,—in the case of some few animals or plants,—to make great changes in particular directions, by selective breeding, it becomes more and more difficult[{163}] as we proceed to continue in the same line. If, for instance, in the case of pigeons, a bird can be produced in six years with head and beak only one-half the size of those whence the process started, are we to say that in twelve years their bulk will be reduced to a quarter, and in twenty-four to an eighth? No one could suppose anything so absurd. Mr. Darwin would answer, that he relies upon the vast periods of geologic time to produce alterations such as we cannot possibly attempt within the few years at our disposal. But, it is replied, no length of time will avail anything for such a purpose, unless there be some force to produce variations in the required direction, to the required extent. Such a force is not proved to exist—all the evidence is against it. Where art is most practised in improvement of breeds, or the obtaining of any peculiarities—as with the speed of racehorses, the size of toy-terriers, or the "points" of prize cattle, it becomes most strikingly apparent that we have reached a limit beyond which species will not vary. And until such a cause as we require is fully proved to exist, its supposed effects cannot be made the basis of scientific argument.
A given animal or plant, [says the Reviewer] appears to be contained, as it were, within a sphere of variation; one individual lies near one portion of the surface, another individual near another part of the surface; the average animal at the centre. Any individual may produce descendants varying in any direction, but is more likely to produce descendants varying towards the[{164}] centre of the sphere, and the variations in that direction will be greater in amount than the variations towards the surface. Thus a set of racers of equal merit indiscriminately breeding will produce more colts and foals of inferior than of superior breed, and the falling off of the degenerate will be greater than the improvement of the select (p. 282).
Similarly M. Blanchard declares:[193]
All investigation and observation make it clear that, while the variability of creatures in a state of nature displays itself in very different degrees, yet in its most astonishing manifestations it remains confined within a circle beyond which it cannot pass.
And the facts of nature, as we know them, far from favouring the instability of species, exhibit a tenacity of form compelling us to treat them as practically immutable. Thus, as Mr. Carruthers points out,[194] in the notoriously variable genus Salix, or willow-tribe, which seems to be actively advancing towards a multiplication of its subdivisions, sub-genera, species, varieties, and hybrid forms,—one species is found, S. polaris, dating from before the Glacial Epoch, which has been driven from England and other lands, by climatic changes, to within the Arctic circle of both Hemispheres,—yet amid this stress of circumstances has preserved its specific identity, down even to the casual variations, which might be supposed to furnish the starting-points for new developments. Yet in this tribe,[{165}] if anywhere, evidence of specific evolution might be looked for.[195]
Other instances seem to show that even under new and trying conditions those creatures survive best which keep closest to the central family type, not those which diverge in any direction. Thus, of European sparrows introduced in America, Mr. Bumpus writes:[196]