The geological phenomena, I repeat, even had the author of the “Vestiges” been consulted in their arrangement, and permitted to determine their sequence, would fail to furnish a single presumption in favor of the development hypothesis. Does the ditch-side of my illustration furnish it with a single favoring presumption? The arrangement and sequence of the various organisms are complete in both the zoological and phytological branch. The flag and reed succeed the fucoid; the fir and juniper succeed the flag and reed; and the hazel, birch, and oak succeed the fir and juniper. In like manner, and with equal regularity, zoophytes, the radiata, the articulata, mollusca, fishes, reptiles, birds, and mammals, are ranged, the superior in succession over the inferior classes, in the true ascending order; and yet we at once see that the evidence of the ditch-side, amounting in the aggregate to no more than this, that the remains of the higher lie over those of the lower organisms, gives not a shadow of support to the hypothesis that the lower produced the higher. For, according to the honest farmer, the fact that any one thing is found lying on the top of any other thing, furnishes no presumption whatever that the thing below stands in the relation of parent to the thing above. And the evidence which the well-ranged organisms of the ditch-side do not furnish, the organisms of the entire geologic scale, even were they equally well ranged, would fail to supply. The fossiliferous portion of the ditch-side of my illustration may be, let us suppose, some five or six feet in thickness; the fossiliferous portion of the earth’s crust must be some five or six miles in thickness. But the mere circumstance of space introduces no new element into the question. Equally in both cases the fact of superposition is not identical with the fact of parental relation, nor even in any degree an analogous fact.
As, however, the succession of remains in the fossiliferous series of rocks is infinitely less favorable to the development hypothesis than that of the organisms of the ditch-side, it is not very surprising that the disciples of the development school should be now evincing a disposition to escape from the ascertained facts of Geology, and the legitimate conclusions based upon these, unto unknown and unexplored provinces of the science; or that they should be found virtually urging, that though some of the ascertained facts may seem to bear against them, the facts not yet ascertained may be found telling in their favor. Such, in effect, is the course taken by the author of the “Vestiges,” in his “Explanations,” when, availing himself of a difference of opinion which exists among some of our most accomplished geologists regarding the first epochs of organized existence, he takes part with the section who hold that we have not yet penetrated to the deposits representative of the dawn of being, and that fossil-charged formations may yet be detected beneath the oldest rocks of what is now regarded as the lowest fossiliferous system. Sir Charles Lyell and Mr. Leonard Hornet represent the abler and better-known assertors of this last view; while Sir Roderick Murchison and Professor Sedgwick rank among the more distinguished assertors of the antagonist one. It would be of course utterly presumptuous in the writer of these pages to attempt deciding a question regarding which such men differ; but in forming a judgment for myself, various considerations incline me to hold, that the point is now very nearly determined at which, to employ the language of Sir Roderick, “life was first breathed into the waters.” The pyramid of organized existence, as it ascends in the by-past eternity, inclines sensibly towards its apex,—that apex of “beginning” in which, on far other than geological grounds, it is our privilege to believe. The broad base of the superstructure, planted on the existing now, stretches across the entire scale of life, animal and vegetable; but it contracts as it rises into the past;—man—the quadrumana—the quadrupedal mammal—the bird—and the reptile—are each in succession struck from off its breadth, till we at length see it with the vertebrata, represented by only the fish, narrowing, as it were, to a point; and though the clouds of the upper region may hide its extreme apex, we infer from the declination of its sides, that it cannot penetrate much farther into the profound. When Steele and Addison were engaged in breaking up, piecemeal, their Spectator Club,—killing off good Sir Roger de Coverly with a defluction, marrying Will Honeycomb to his tenant’s daughter, and sending away Captain Sentry and Sir Andrew Freeport to their estates to the country,—it was shrewdly inferred that the “Spectator” himself was very soon to quit the field; and the sudden discontinuance of his lucubrations justified the inference. And a corresponding style of reasoning, based on the corresponding fact of the breaking up and piecemeal disappearance of the group of organized being, seems equally admissible. It is somewhat difficult to conceive how at least many more volumes of the geologic record than the known ones could be got up without the club. Further,—so far as yet appears, the fish must have lived in advance of the reptile during the three protracted periods of the Old Red Sandstone, the two still more protracted periods of the Upper and Lower Silurians, and the perhaps more protracted period still of the Cambrian deposits;—in all, apparently, a greatly more extended space than that in which the reptile lived in advance of the quadrupedal mammal, or the quadrupedal mammal lived in advance of man. On principles somewhat similar to those on which, with reference to the average term of life, the genealogist fixes the probable period of some birth in his chain of succession of which he cannot determine the exact date, it seems natural to infer that the birth of the fish should have taken place at least not earlier than the times of the Cambrian system.
There is another consideration, of at least equal, if not greater weight. A general correspondence is found to obtain in widely-separated localities, in the organic contents of that lowest band of the Lower Silurian or Cambrian system in which fossils have been detected. In Russia, in Sweden, in Norway, in the Lake district of England, and in the United States, there are certain rocks which occupy relatively the same place, and enclose what may be described generally as the same remains. They occur in Scandinavia as that “fucoidal band” of Sir Roderick Murchison which forms the base of the vast Palæozoic basin of the Baltic; they exist in Cumberland and Westmoreland as the Skiddaw slates of Professor Sedgwick, and bear also their fucoidal impressions, blent with graptolites; they are present in North America as those Potsdam sandstones of the States’ geologists in which fucoids so abound, mixed with a minute lingula, that they impart to some portions of the strata a carboniferous character. But with these deep-lying beds in all the several localities, thousands of miles apart, in which their passage into the inferior deposits has been traced, fossils cease. And why cease with them? In one locality the ancient ocean may have been of such a depth in the period immediately previous, and represented, in consequence, by the strata immediately beneath, that no animal could have lived at its bottom,—though I do not well see why the remains of those animals who, like the shark and pilot-fish, are frequently seen swimming over the profoundest depths, might not, did such exist at the time, be notwithstanding found at its bottom; or in another locality every trace of organization in the nether rocks may have been obliterated, at some posterior period, by fire. But it is difficult to imagine that that uniform cessation of organized life at one point, which seems to have conducted Sir Roderick Murchison and Professor Sedgwick to their conclusion, should have been thus a mere effect of accident. Accident has its laws, but uniformity is not one of them; and should the experience be invariable, as it already seems extensive, that immediately beneath the fucoidal beds organic remains cease, I do not see how the conclusion is to be avoided, that they represent the period in which at least existences capable of preservation were first introduced. Every case of coincident cessation which has occurred since the determination of the second case, must be reckoned, not simply as an additional unit in evidence, but, on the principles which determine mathematical probability, as a unit multiplied first by the chances against its occurrence, regarded as a mere contingency in that exact formation, and second, by the sum of all the previous occurrences at the same point.
In this curious question, however, which it must be the part of future explorers in the geological field definitely to settle, the Lamarckian can have no legitimate stake. It is but natural that, in his anxiety to secure an ultimate retreat for his hypothesis, he should desire to see that darkness in which ghosts love to walk settling down on the extreme verge of the geological horizon, and enveloping in its folds the first beginnings of life. But even did the cloud exist, it is, if I may so express myself, on its nearer side, where there is light,—not within nor beyond it, where there is none,—that the battle must be fought. It is to Geology as it is known to be, that the Lamarckian has appealed,—not to Geology as it is not known to be. He has summoned into court existing witnesses; and, finding their testimony unfavorable, he seeks to neutralize their evidence by calling from the “vasty deep,” of the unexamined and the obscure, witnesses that “won’t come,”—that by the legitimate authorities are not known even to exist,—and with which he himself is, on his own confession, wholly unacquainted, save in the old scholastic character of mere possibilities. The possible fossil can have no more standing in this controversy than the “possible angel.” He tells us that we have not yet got down to that base-line of all the fossiliferous systems at which life first began; and very possibly we have not. But what of that? He has carried his appeal to Geology as it is;—he has referred his case to the testimony of the known witnesses, for in no case can the unknown ones be summoned or produced. It is on the evidence of the known, and the known only, that the exact value of his claims must be determined; and his appeal to the unknown serves but to show how thoroughly he himself feels that the actually ascertained evidence bears against him. The severe censure of Johnson on reasoners of this class is in no degree over-severe. “He who will determine,” said the moralist, “against that which he knows, because there may be something which he knows not,—he that can set hypothetical possibility against acknowledged certainty,—is not to be admitted among reasonable beings.”
But the honest farmer’s reminiscences of his deceased neighbor the weaver, and his use at second-hand of Hume’s experience-argument, naturally lead me to another branch of the subject.
LAMARCKIAN HYPOTHESIS OF THE ORIGIN OF PLANTS.
ITS CONSEQUENCES.
I have said that the curiously-mixed, semi-marine, semi-lacustrine flora of the Lake of Stennis became associated in my mind, like the ancient Asterolepis of Stromness, with the development hypothesis. The fossil, as has been shown, represents not inadequately the geologic evidence in the question,—the mixed vegetation of the lake may be regarded as forming a portion of the phytological evidence.
“All life,” says Oken, “is from the sea. Where the sea organism, by self-elevation, succeeds in attaining into form, there issues forth from it a higher organism. Love arose out of the sea-foam. The primary mucus (that in which electricity originates life) was, and is still, generated in those very parts of the sea where the water is in contact with earth and air, and thus upon the shores. The first creation of the organic took place where the first mountain summits projected out of the water,—indeed, without doubt, in India, if the Himalaya be the highest mountain. The first organic forms, whether plants or animals, emerged from the shallow parts of the sea.” Maillet wrote to exactly the same effect a full century ago. “In a word,” we find him saying, in his “Telliamed,” “do not herbs, plants, roots, grains, and all of this kind that the earth produces and nourishes, come from the sea? Is it not at least natural to think so, since we are certain that all our habitable lands came originally from the sea? Besides, in small islands far from the continent, which have appeared but a few ages ago at most, and where it is manifest that never any man had been, we find shrubs, herbs, roots, and sometimes animals. Now, you must be forced to own either that these productions owed their origin to the sea, or to a new creation, which is absurd.”
It is a curious fact, to which, in the passing, I must be permitted to call the attention of the reader, that all the leading assertors of the development hypothesis have been bad geologists. Maillet had for his errors and deficiencies the excellent apology that he wrote more than a hundred years ago, when the theory of a universal ocean, promulgated by Leibnitz nearly a century earlier, was quite as good as any of the other theories of the time, and when Geology, as a science, had no existence. And so we do not wonder at an ignorance which was simply that of his age, when we find him telling his readers that plants must have originated in the sea, seeing that “all our habitable lands came originally from the sea;” meaning, of course, by the statement, not at all what the modern geologist would mean were he to employ even the same words, but simply that there was a time when the universal ocean covered the whole globe, and that, as the waters gradually diminished, the loftier mountain summits and higher table-lands, in appearing in their new character as islands and continents, derived their flora from what, in a universal ocean could be the only possible existing flora,—that of the sea. But what shall we say of the equally profound ignorance manifested by Professor Oken, a living authority, whom we find prefacing for the Ray Society, in 1847, the English translation of his “Elements of Physio-philosophy?” “The first creation of the organic took place,” we find him saying, “where the first mountain summits projected out of the sea,—indeed, without doubt, in India, if the Himalaya be the highest mountain.” Here, evidently, in this late age of the world, in which Geology does exist as a science, do we find the ghost of the universal ocean of Leibnitz walking once more, as if it had never been laid. Is there now in all Britain even a tyro geologist so unacquainted with geological fact as not to know that the richest flora which the globe ever saw had existed for myriads of ages, and then, becoming extinct, had slept in the fossil state for myriads of ages more, ere the highest summits of the Himalayan range rose over the surface of the deep? The Himalayas disturbed, and bore up along with them in their upheaval, vast beds of the Oolitic system. Belemnites and ammonites have been dug out of their sides along the line of perpetual snow, seventeen thousand feet over the level of the sea. What in the recent period form the loftiest mountains of the globe, existed as portions of a deep-sea bottom, swum over by the fishes and reptiles of the great Secondary period, when what is now Scotland had its dark forests of stately pine,—represented in the present age of the world by the lignites of Helmsdale, Eathie, and Eigg,—and when the plants of a former creation lay dead and buried deep beneath, in shales and fire-clay,—existing as vast beds of coal, or entombed in solid rock, as the brown massy trunks of Granton and Craigleith. And even ere these last existed as living trees, the coniferous lignite of the Lower Old Red Sandstone found at Cromarty had passed into the fossil state, and lay as a semi-calcareous, semi-bituminous mass, amid perished Dipterians and extinct Coccostei. So much for the Geology of the German Professor. And be it remarked, that the actualities in this question can be determined by only the geologist. The mere naturalist may indicate from the analogies of his science, what possibly might have taken place, but what really did take place, and the true order in which the events occurred, it is the part of the geologist to determine. It cannot be out of place to remark, further, that geological discovery is in no degree responsible for the infidelity of the development hypothesis; seeing that, in the first place, the hypothesis is greatly more ancient than the discoveries, and, in the second, that its more prominent assertors are exactly the men who know least of geological fact. But to this special point I shall again refer.