Let it not be thought irreligious to anticipate the possible establishment of the supposition now under discussion. It cannot be irreverent to think that the bestowal of life upon a particle of matter too minute for human eye to see, requires no more special apparatus than that allotted to the exquisite crystals of the frost. ‘Out of whose womb came the ice? and the hoary frost of heaven, who hath gendered it?’ Yet in the workmanship of these a Divine hand is to the full as visible as in a diatom or a puff-ball. That the life-giving energy should have been exhausted in a single effort, is contrary beyond doubt to the analogy of religion, whatever may be thought of the analogy of nature.
On the other hand, let it not be thought unscientific to advocate the claims of an unproved hypothesis. It is the nature of hypotheses to be unproved. As they gather proof, the hypothetical becomes a theory. At length the theory goes on to demonstration. The use of hypotheses has often been explained. The human mind is easily exhausted by the observation of numerous incoherent facts. It is impelled to arrange and classify, to find some thread or threads of association on which the facts may be strung, some principle on which they may be parcelled out into groups. The arrangement may be erroneous, the explanatory principle untrue; they may be so plausible, so apparently satisfactory, so fascinating withal in general aspect, as for a long time to hinder the real solution of great problems; and nevertheless it may be judged that their services in the advancement of knowledge far outweigh the hindrances caused by the too servile acceptance accorded them. The foibles of a great writer may long infect the literature which his greatness has ennobled. A constitution grandly conceived in proportion to the moral and social ideas prevailing at the time of its conception may be clung to with servility long after it has been outstripped by the progress of civilization. But neither the genius of the poet nor the skill of the lawgiver could be spared in its own day and generation; neither could have been sacrificed to prevent the follies of the plagiarist, or the dulness of eyes that in after ages might read the letter without discerning the spirit.
We may almost say that a bad hypothesis is better than none; but a wrong hypothesis need not be a bad one. It may tend so to group around it the facts contributed by supporters and opponents, that when the real explanation of them all comes to be suggested, the fraternization of the confronting armies may be easy, and the truth be greeted and acknowledged with general acclaim.
THE IMPERFECTION OF THE GEOLOGICAL RECORD.
The general who is for ever counter-marching and skilfully executing retrograde movements cannot always sustain the enthusiasm of his own troops, much less excite in his favour that of the civilian multitude. To many minds, the reliance placed on the imperfection of the geological record appears to be a rather damaging retreat in the strategy of science. They were just beginning to believe in geology as a wonderful revelation of the past history of the globe, when suddenly they are told that the fragments of that history which have been saved are merely tattered pages out of different chapters, giving no adequate notion of the enormous bulk and varied contents of the whole volume. Since, without the geological evidence of time’s duration and of the countless changes in organic structures which that duration embraces, the theory of development could never have been imagined, it seems half ungrateful and inconsistent in the author of the theory to turn round upon geological evidence and tax it with its extreme poverty and even delusive misleading appearances. But, in fact, Mr. Darwin in no way detracts from the value of geological evidence. The researches necessary to extend it are invested, to those who accept his theory, with tenfold interest. The deficiencies and interruptions in it which he has pointed out as necessarily occurring must sooner or later have become apparent. They were dangerous to science only as long as they were unobserved, or not sufficiently taken into account.
That the record is really imperfect is not a matter which admits of controversy. No one supposes that every species and variety that ever existed in past ages on the globe is represented at this very day by fossil specimens in prime enough condition to exhibit all the characteristics of the creature as it once lived. No one supposes that, if such specimens existed, all of them ever could or would be found by human beings. It is not in the nature of a fossil to present all the characteristics of the creature as it once lived. It cannot possibly do it; for the fossil is without life and motion. There is no respiration, no circulation of the blood going on. As a rule, only the hard parts of the creature, such as shell, scales, or bony skeleton, can be preserved. In most cases all these relics have been chemically altered. Nevertheless, in fossils from the very lowest strata, from the very earliest formations that yield any, we find certain analogies to creatures now living. We reason from these analogies without any hesitation to the characteristics which the fossil creature will probably have presented in its living state. Our reasonings may often be erroneous, but the mere fact of our accepting the apparent analogies as a ground for reasoning at all, implies a belief in the uniformity of the conditions of animal existence between our own times and the most distant ages of the past. We argue as if generation had succeeded generation without interruption, not as if there had been new independent creations from time to time, since these would imply new conditions replacing the old, and make the argument from analogy between the items of the different creations of no value. For these independent creations, whether capricious or not in themselves, could only exhibit to our minds the symptoms of caprice. The mere fact of their being independent one of another would be so wanting in congruity with all the rest of our experience, that we should reasonably expect their minor details as well as the general plan to be wholly fantastic. In other words, the fossil memorials of life in past ages, imperfect as we confess and maintain them to be, still present so many general resemblances to one another and to living structures of the present day, that if they do not prove the continuity of life upon the globe, they cannot be held to prove anything at all; they should be regarded as a very elaborate practical joke played upon the human reason.
Palæontology is defined as ‘the science which treats of fossil remains both animal and vegetable.’ This principle of the continuity of life from age to age may be considered as one of its definite acquisitions. There is no single point of geological time at which it can be said, ‘at this epoch clearly all old species had passed away, all kinds of life had become new.’ Not only is there no indication of such a break, but there is the strongest evidence against any such having ever occurred. In spite, however, of the completeness of the evidence required for proving this single conclusion, the general incompleteness and enormous deficiencies in some parts of the palæontological record can be established beyond dispute. We are in the position of a man who has kept the title-deeds to a large estate, while almost all the estate itself has been buried under the encroachments of the sea. Here and there some old landmarks may be discernible far out in the waters, showing the extent of what had once been meadow and woodland, farm and garden, but unable to show how these were distributed, or to exhibit any of their details.
Mr. Parfitt, in his paper on ‘Fossil Sponge Spicules,’ told the Devonshire Association last year (1870) that we have evidence more or less exact of sponges in a fossil state as far back in time as the Silurian system, mentioning specimens of Acanthospongia Siluriensis, Cliona antiqua, and Cliona prisca, and stating in regard to the two latter that the genus is still in our own seas. He then referred to large masses of a fossil in the Devonian rocks of Cornwall, believed by some to be sponges, and by others to be the remains of fish. That these are in reality fish-remains has, in fact, been shown pretty conclusively[59]. From this point, however, up to the Great Oolite, Mr. Parfitt tells us that scarcely a vestige of the sponges is to be found, although since that time they have been very abundant. Between the Silurian and the Great Oolite the interval of time must have been enormous. It is occupied by a vast series of sedimentary rocks, embracing very varied mineral characteristics. From this series our museums have been, and are still being, supplied with vast heaps of fossil organic structures, including among numerous others, plants and corals and fish and reptiles. Through all that protracted period there is no reason to suppose, in regard to the outer rind of the globe, that the general conditions of earth, air, and water were other than they are now. All England may have been under water; delicate creatures may have wintered at the North Pole for the sake of its genial climate; and an infinity of other local and temporary differences may have prevailed, without making the habitable globe of those days essentially different from our own. The laws of chemistry and mechanics, the laws of heat and motion, must have been just the same as they are now. Then, as now, there must have been oceans and continents, winds and currents, forests growing, decaying, and being buried, sand and chalk being deposited in layers, molten minerals thrown up by volcanoes, ice forming at a definite temperature, glaciers scoring the rocks, icebergs transporting boulders, rains and rivers slowly washing down the hills, and waves corroding the cliffs on the sea-shore. We have evidence also that life in many forms abounded. Those forms, though seldom transmitted to creatures of the present day with anything approaching an exact likeness, can yet be classified under the same general names with the most modern forms of life. Now sponges are forms of an extremely simple organization. The silicious spicules are well adapted for the wear and tear of a fossil existence. In the greensand and the chalk they are actually found in extraordinary abundance. It would be inconvenient upon any theory to have to suppose these very simple structures introduced into the world for the first time quite late in the series of living organisms, and after beings much more complicated and higher in the scale of existence, unless, indeed, we suppose that about the time of the Great Oolite the evolution of man was first thought of, and the sponge accordingly prepared for him to wash his face with. But even if the bath and the basin be admitted as the final causes of sponge-existence, the conception of it must be carried back, as we have seen, to the Silurian period; while, according to Mr. Parfitt, the immense interval of Lias and Trias, Permian, Carboniferous, and Devonian remains black and spongeless, as though it were the appropriate era of the great unwashed. But if the Darwinian theory be a true one, sponge-life having begun in the Silurian period, and being in existence now, must have been continuous through the whole interval; every single deposit in the entire series since the Silurian must have been contemporary with some of the sponges; and, as a matter of fact, Mr. Parfitt’s statement, however true of the condition of our knowledge a few years back, must now be qualified by the addition of several species spread over the interval in Britain alone, even if we exclude some indefinite structures, of which no opinion can be at present pronounced with safety. Mr. Parfitt himself, in a paper read at Honiton in 1868, remarks that ‘the Devonian formation has furnished a great number of specimens of what appear to be species of sponges.’ From Permian and Triassic beds on the continent of Europe, a very large number of forms are said to be more or less distinctly made out. Mr. Salter, in 1864, reported the discovery of Protospongia Fenestrata in the Lingula flags of St. David’s, thus carrying back this form of life beyond the Silurian to the Cambrian era. It is an interesting illustration of the great ambiguity of these ancient fossils, that two such authorities as Mr. Salter and Dr. Bowerbank differed about the Protospongia, the one supposing it to exhibit the spicules, the other the fibre of the sponge. The simple facts that species have to be moved backwards and forwards between the amorphozoic and zoophytic groups, that relics may pass for fish in one year and sponges in another, and by-and-by be recognised again as fish, show the often imperfect condition of the record, even where it is not a complete blank.