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to find fertile hybrids. Great naturalists have maintained that none such can be found ; but Cuvier declined to commit himself to this assertion. That all varieties are mutually fertile was clear; that almost all species are mutually sterile, if not in the first in the second degree, was clear also. Whether there were exceptions to this seemingly universal rule remained to be seen.
Mr. Darwin, however, has found none. “ It is difficult,” he admits, “perhaps impossible, to bring forward one case of the hybrid offspring of two animals clearly distinct, being themselves perfectly fertile.” And again, “I doubt whether any case of a perfectly fertile hybrid animal can be considered as thoroughly well authenticated." 28 Should it ever be so authenticated, the result would be the establishment of an exception to an all but unrelaxing rule, and the failure in that particular case of a test all but universally available. Other tests might indeed remain. If a wolf-like animal from Jupiter were to inter-breed with a dog-like animal from Saturn, and produce a fertile hybrid race, it would not follow that the two parents had sprung from one stock. Our author's account of his poor success in this first and easiest of his quests may prepare us however for a still more signal failure in that far less hopeful
quest which is vital to his main doctrine. No trace, none, of infertile varieties. The boundary line will not shift; species stands forth an inflexible frontier which no manipulation can "rectify.” A prolific mule remains, as of old, a peg on which to hang a proverb for an impossibility ;29 nor will pouter and fan-tail, by refusing to breed, disown their common pigeonhood. The veto neither slackens nor spreads ; nature keeps to her code of prohibited degrees, neither relaxing nor extending them. So huge is the difficulty that it earns for Mr. Darwin the special condolence of the Westminster Review. There is comfort, to be sure, and somewhat of compensation, in the thought that the ape is nearer man than the ape-like lemur is to the ape; but there is sadness, nevertheless, in the constrained confession that the facts of animal fertility and infertility cannot as yet be made to square with Mr. Darwin's scheme, or allow it to take rank as “the theory of species.” 30 So these gentlemen are meanwhile in the plight of that brace of philosophers, one of whom devoted his energies to the milking of a he-goat, while the other—held the pail.
20. As matters stand, then, the horse, e. g. no more explains the origin of its near congener the ass, than either would explain an equine quadruped in Mars or the Moon. And if this slight interval cannot be bridged, what shall we say to those other and incomparably greater chasms, not only confronting us in contemporary nature, but sculptured out to us on the sepulchral rocks, from top to bottom of the geologic scale, a million ages down ?
21. The tale told by the old graves of the earth, where nature has done her own embalming more effectually than Egyptian art, is all-important in the appraising of Mr. Darwin's scheme. And it is, on the face of it, as he feels, against him. His chapter on the geological record can only be described as an ingenious retreat from the facts of our knowledge on the possibilities of our ignorance. “ Our theorists,” says Paley, “ having eternity to dispose of, are never sparing in time ;” and Mr. Darwin, as we have seen, is most lavish in his drafts on the past. But the past, protracted at will, being against him, it is necessary further to suggest that if the past had been properly chronicled — if the museum of nature had been at all well kept—it might and would have been for him. No special pleading, however, can shake the facts. The rocky folds of the earth are now contemplated by its students, less as a succession of mineral masses than as a many-drawered cabinet of fossil remains.31 In obedience to this principle of classification, Palæozoic, Mesozoic, and Cænozoic have taken the place of Primary, Secondary, and Tertiary, put forth when the science was in its infancy; and these names answer in Geology to the division of Universal History into Ancient, Mediæval, and Modern. If for every hundred years of history we put a thousand feet of stratification, we should further have a very close mnemonic parallel, marking off at once the ascertained depth of strata and the relative duration of the former life-systems of the globe. Neglecting the proportions, which, from the “lingula” or first distinct fossil-beds upwards, may be roughly estimated as 6, 3, 1, the chart shows in outline the state of the record.—(Page 38.) Of this, taken
( as it stands, no two readings are possible. All geologists who have no theory of species to propound, but only its fossil phenomena to register, are impressed with but one conviction, from the gradual dearth, the all but total, and the at last total disappearance of memorials of life from the lower Palæozoic strata --- and that is, that life was just then beginning, or had not yet begun; for had life abounded in these lower zones as in the upper zones of the self-same system, it would have left, the facilities of preservation being precisely alike, simi
MAN. MAMMALIAN CLIMAX.
Wave-brained Mammalia : Ape, Dog,
Lion, Elephant, Ox, Whale, &c.
Eocene Period : Bat, Dolphin, Bee, &c.
Second Period of Organic Penury.
First Period of Organic Penury.
Reign of ARCH-EXOGENS and ENDOGENS.
Fruit and Forest Trees, Palms, Grasses, &c.
Second Epoch of Eflorescence.
Dawn of Arch-Exogens.
Cycloids and Ctenoids : soft-scaled and
Reign of GYMNOGENS and ACROGENS.
18,000 Feet ?
Firs, Cycads, Ferns, &c.
Birds and Marsupial Mammals.
Magnesian Limestone Dawn of Endogens.
First Epoch oj Eflorescence.
Old Red Sandstone
Dawn of Gymnogens.
Placoid and Ganoid Fishes: armour-clad.
* In this Chart scale is disregarded, a large margin is allowed for under-developed Strata, and all the Geological Systems are referred to a
mid-member of the main groups.