Duke of Argyll
 The most delightful of all Mr. Darwin's works is the first be ever wrote. It is his Journal as the Naturalist of H.M.S. 'Beagle' in her exploring voyage round the world from the beginning of 1832 to nearly the end of 1836. It was published in 1842, and a later edition appeared in 1845. Celebrated as this book once was, few probably read it now. Yet in many respects it exhibits Darwin at his best, and if we are ever inclined to rest our opinions upon authority, and to accept without doubt what a remarkable man has taught, I do not know any work better calculated to inspire confidence than Darwin's Journal. It records the observations of a mind singularly candid and unprejudicedfixing upon nature a gaze keen, penetrating, and curious, but yet cautious, reflective, and almost reverent. The thought of how little we knowof how much there is to be known, and of how hardly we can learn itis the thought which inspires the narrative as with an abiding presence. There is, too, an intense love of nature and an intense admiration of it, the expression of which is carefully restrained and measured, but which seems often to overflow the limits which are self-imposed. And when Man, the highest work of nature, but, not always its happiest or its best, comes across his path, Darwin's observations are always noble. 'A kindly man moving among his kind' seems to express his spirit. He appreciates every high calling, every good work, however far removed it may be from that to which be was himself devoted. His language about the missionaries of Christianity is a signal example, in striking contrast with the too common language of  lesser men. His indignant denunciation of slavery presents the same high characteristics of a mind eminently gentle and humane. In following him we feel that not merely the intellectual but the moral atmosphere in which we move is high and pure. And then, besides these great recommendations, there is another which must not be overlooked. We have Darwin here before he was a Darwinian. He embarked on that famous voyage with no preconceived theories to maintain. Yet he was the grandson of Dr. Erasmus Darwina man very famous in his day, who was the earliest popular exponent of Evolution as explaining the creative work, and who, both in prose and verse, had made it familiar as at least a dream and a poetic speculation. Charles Darwin in his Journal seems as unconscious of that speculation as if he had never heard of it, or was as desirous to forget it as if he concurred in the ridicule of it which had amused the readers of the Anti-Jacobin. Only once in the Journal is there any allusion to such speculations, and then only to the form in which they had been more scientifically clothed by the French naturalist Lamarck. This is all the more curious and interesting, since here and there Charles Darwin records some facts, and enters upon some reasoning, in which we can now see the undeveloped germs of the theory which ultimately took entire possession of his mind. But that theory was, beyond all question, the later growth of independent observation and of independent thought. He started freefree at least, so far as his own consciousness was concerned. The attitude of his mind was at that time receptive, not constructive. It was gathering material, but it had not begun to build. It was watching, arranging, and classifying facts. But it was not selecting from among them such as would fit a plan. Still less was it setting aside any that did not appear to suit. He might have said with truth that which was said by a greater man before him: Hypotheses non fingo.' This is one of the many great charms of the book.
And yet there was one remarkable exception. Like every other voyager who has traversed the vast Southern Ocean, he was struck, impressed, and puzzled by its wonderful coral reefs, its thousands of coral islands, and its still more curious coral 'atolls.'[Detailed negative appraisal of Darwins theory of coral reefs follows to p. 300 ff.]
 So certain was Darwin of these conclusions that he adds, in a most unwonted tone of confidence :
I venture to defy any one to explain in any other manner how it is possible that numerous islands should be distributed throughout vast areasall the islands being low, all being built of corals, absolutely requiring a foundation within a limited depth from the surface.1
The voyage of the Beagle' ended in the autumn of 1836, and Darwin landed in England on the 2nd of October. He proceeded to put into shape his views on the coral islands of the Pacific, and in May 1837 they were communicated to the public in a paper read before the Geological Society of London. His theory took the scientific world by storm. It was well calculated so to do. There was an attractive grandeur in the conception of some great continent sinking slowly, slowly, into the vast bed of the Southern Ocean, having all its hills and pinnacles gradually covered by coral reefs as in succession they sank down to the proper depth, until at last only its pinnacles remained as the basis of atolls, and these remained, like buoys upon a wreck, only to mark where some mountain peak had been finally submerged. Besides the grandeur and simplicity of this conception, it fitted well into the Lyellian doctrine of the bit by bit' operation of all geological causesa doctrine which had then already begun to establish its later wide popularity. Lyell had published the first edition of his famous Principles in January 1830that is to say, almost two years before the Beagle' sailed. He had adopted the volcanic theory of the origin of the coral islands; and it is remarkable that be had nevertheless suggested the idea, although in a wholly different connection, that the Pacific presented in all probability an area of subsidence. Darwin most probably had this suggestion in his mind when he used it and adopted it for an argument which its author had never entertained.2 However this may be, it must have prepared the greatest living teacher of geology to adopt the new explanation which turned his own hint to such wonderful account. And adopt it he did, accordingly. The theory of the young naturalist was hailed with acclamation. It was a magnificent generalisation. It was soon almost universally accepted with admiration and delight. It passed  into all popular treatises, and ever since for the space of nearly half a century it has maintained its unquestioned place as one of the great triumphs of reasoning and research. Although its illustrious author has since eclipsed this earliest performance by theories and generalisations still more attractive and much further reaching, I have heard eminent men declare that, if he had done nothing else, his solution of the great problem of the coral islands of the Pacific would have sufficed to place him on the unsubmergeable peaks of science, crowned with an immortal name.
And now comes the great lesson. After an interval of more than five-and-thirty years the voyage of the 'Beagle' has been followed by the voyage of the Challenger,' furnished with all the newest appliances of science, and manned by a scientific staff more than competent to turn them to the best account. And what is one of the many results which have been added to our knowledge of nature-to our estimate of the true character and history of the globe we live on? It is that Darwin's theory is a dream. It is not only unsound, but it is in many respects directly the reverse of truth. With all his conscientiousness, with all his caution, with all his powers of observation, Darwin in this matter fell into errors as profound as the abysses of the Pacific. All the acclamations with which it was received were as the shouts of an ignorant mob. It is well to know that the plebiscites of science may be as dangerous and as hollow as hose of politics. The overthrow of Darwin's speculation is only beginning to be known. It has been whispered for some time. The cherished dogma has been dropping very slowly out of sight. Can it be possible that Darwin was wrong? Must we indeed give up all that we have been accepting and teaching for more than a generation? Reluctantly, almost sulkily, and with a grudging silence as far as public discussion is concerned, the ugly possibility has been contemplated as too disagreeable to be much talked about. The evidence, old and new, has been weighed and weighed again, and the obviously inclining balance has been looked at askance many times. But despite all averted looks I apprehend that it has settled to its place for ever, and Darwin's theory of the coral islands must be relegated to the category of those many hypotheses which have indeed helped science for a time by promoting and provoking further investigation, but which in themselves have now finally kicked the beam.'
But this great lesson will be poorly learnt unless we read and study it in detail. What was the flaw in Darwin's reasoning, apparently so close and cogent? Was it in the facts, or was it in the inferences? His facts in the main were right; only it has been found that they fitted into another explanation better than into his. It was true that the corals could only grow in a shallow sea, not deeper than from twenty to thirty fathoms. It was true that they needed some foundation provided for them at the required depth.  It was true that this foundation must be in the pure and open sea with its limpid water, its free currents, and its dashing waves. It was true that they could not flourish or live in lagoons or in channels, however wide, if they were secluded and protected from oceanic waves. One error, apparently a small one, crept into Darwin's array of facts. The basis or foundation on which corals can grow, if it satisfied other conditions, need not be solid rock. It might be deepsea deposits if these were raised or elevated near enough the surface. Darwin did not know this for it is one of his assumptions that coral 'cannot adhere to a loose bottom.'3 The Challenger' observations show that thousands of deep-sea corals and of other lime-secreting animals flourish on deep-sea deposits at depths much greater than those at which true reef-building species are found. The dead remains of these deeper-living animals, as well as the dead shells of pelagic species that fall from the surface waters, build up submarine elevations towards the sea level. Again, the reef-building coral will grow upon its own debrisrising, as men, morally and spiritually, are said by the poet to do, on stepping-stones of their dead selves to higher things.' This small error told for much; for if coral could grow on deep-sea deposits when lifted up, and if it could also grow seaward, when once established, upon its own dead and sunken masses, then submarine elevations and not submarine subsidences might be the true explanation of all the facts. But what of the lagoons and the immense areas of sea behind the fringing reefs? How could these be accounted for? It was these which first impressed Darwin with the idea of subsidence. They looked as if the land had sunk behind the reef, leaving a space into which the sea had entered, but in which no fresh reefs could grow. And here we learn the important lesson that an hypothesis may adequately account for actual facts, and yet nevertheless may not be true. A given agency may be competent to produce some given effect, and yet that effect may not be due to it, but to some other. Subsidence would or might account for the lagoons and for the protected seas, and yet it may not be subsidence which has actually produced them.
Darwin's theory took into full account two of the great forces which prevail in nature, but it took no account of another, which is comparatively inconspicuous in its operations, and yet is not less powerful than the vital energies, and the mechanical energies, which move and build up material. Darwin had thought much and deeply on both of these. He called on both to solve his problem. To the vital energy of the coral animals he rightly ascribed the power of separating the lime from sea-water, and of laying it down again in the marvellous structures of their calcareous homes. In an eloquent and powerful passage he describes the wonderful results which this energy achieves in constructing breakwaters which repel and resist  miles of coast. On the subterranean forces which raise and depress the earth's crust he dweltat least enough. But he did not know, because the science of his day had not then fully grasped, the great work performed by the mysterious power of chemical affinity, acting through the cognate conditions of aqueous solution. Just as it did not occur to him that a coral reef might advance steadily seaward by building ever fresh foundations on its own fragments when broken and submerged, or that the vigorous growth of the reefs to windward was due to the more abundant supply of food brought to the reef-building animals from that direction by oceanic currents, so did it never occur to him that it might melt away to the rear like salt or sugar, as the vital energy of the coral animals failed in the sheltered and comparatively stagnant water. It was that vital energy alone which not only built up the living tubes and cells, but which filled them with living organic matter capable of resisting the chemical affinities of the inorganic world. But when that energy became feeble, and when at last it ceased, the once powerful structure descended again to that lower level of the Inorganic, and subject to all its laws. Then, what the ocean could not do by the violence of its waves, it was all-potent to do by the corroding and dissolving power of its calmer lagoons. Ever eating, corroding, and dissolving, the back waters of the original fringing reefthe mere pools and channels left by the outrageous sea as it dashed upon the shorewere ceaselessly at work, aided by the high temperature of exposure to blazing suns, and by the gases evolved from decaying organisms. Thus the enlarging area of these pools and channels spread out into wide lagoons, and into still wider protected seas. They needed no theory of subsidence to account for their origin or for their growth. They would present the same appearance in a slowly rising, a stationary, or a slowly sinking area. Their outside boundary was ever marching further outward on submarine shoals and banks, and ever as it advanced in that direction its rear ranks were melted and dissolved away. Their inner boundarythe shores of some island or of some continent-might be steady and unmoved, or it might be even rather rising instead of sinking. Still, unless this rising were such as to overtake the advancing reef, the lagoon would grow, and if the shores were steady, it would widen as fast as the face of the coral barrier could advance. Perhaps, even if such a wonderful process had ever occurred to Darwineven if he had grasped this extraordinary example of the 'give and take' of natureof the balance of opposing forces and agencies which is of the very essence of its system, he would have been startled by the vast magnitude of the operations which such an explanation demanded. In its incipient stages this process is not only easily conceivable, but it may be seen in a thousand places and in a thousand stages of advancement. There are islands without number in which the fringing  reef is still attached to the shore, but in which it is being pitted,' holed, and worn into numberless pools on the inner surfaces, where the coral is in large patches dead or dying, and where its less soluble ingredients are being deposited in the form of coral sand. There are thousands of other cases where the lagoon interval between the front of the reef and the shores has been so far widened that it is taking the form of a barrier, as distinguished from a fringing reef, and where the lagoon can be navigated by small boats. But when we come to the larger atolls, and the great seas included between a barrier reef and its related shores, the mind may well be staggered by the enormous quantity of matter which it is suggested has been dissolved, removed, and washed away. The breadth of the sheltered seas between barrier reefs and the shore is measured in some cases not by yards or hundreds of yards, not by miles but by tens of miles, and this breadth is carried on in linear directions, not for hundreds of miles, but for thousands. And yet there is one familiar idea in geology which might have helped Darwin, as it is much needed to help us even now, to conceive it. It is the old doctrine of the science, long ago formulated by Hutton, that the work of erosion and of denudation must be equal to the work of deposition. Rocks have been formed out of the ruins of older rocks, and those older rocks must have been worn down and carried off to an equivalent amount. So it is here, with another kind of erosion and another kind of deposition. The coral-building animals can only get their materials from the sea, and the sea can only get its materials by dissolving it from calcareous rocks of some kind. The dead corals are among its greatest quarries. The inconceivable and immeasurable quantities which have been dissolved out of the lagoons and sheltered seas of the Pacific and of the Indian Ocean, are not greater than the immeasurable quantities which are again used up in the vast new reefs of growing coral, and in the calcareous covering of an inconceivable number of other marine animals.
Here then was a generalisation as magnificent as that of Darwin's theory. It might not present a conception so imposing as that of a whole continent gradually subsiding, of its long coasts marked by barrier reefs, of its various hills and irregularities of surface marked by islands of corresponding size, and finally of the atolls which are the buoys indicating where its highest peaks finally disappeared beneath the sea. But, on the other hand, the new explanation was more like the analogies of naturemore closely correlated with the wealth of her resources, with those curious reciprocities of service which all her agencies render to each other, and which indicate so strongly the ultimate unity of her designs. This grand explanation we owe to Mr. John Murray, one of the naturalists of the Challenger' expedition, a man whose enthusiasm for science, whose sagacity and candour of mind, are not inferior to those of Darwin, and whose  literary ability is testified by the splendid volumes of Reports now in course of publication under his editorial care. Mr. Murray's new explanation of the structure and origin of coral reefs and islands was communicated to the Royal Society of Edinburgh in 1880,4 and supported with such a weight of facts and such a close texture of reasoning that no serious reply has ever been attempted. At the same time the reluctance to admit such an error in the great Idol of the scientific world, the necessity of suddenly disbelieving all that had been believed and repeated in every form, for upwards of forty years of cancelling what had been taught to the young of more than a whole generationhas led to a slow and sulky acquiescence, rather than to that joy which every true votary of science ought to feel in the discovery of a new truth andnot lessin the exposure of a long-accepted error. Darwin himself had lived to hear of the new solution, and with that splendid candour which was eminent in him, his mind, though now grown old in his own early convictions, was at least ready to entertain it, and to confess that serious doubts had been awakened as to the truth of his famous theory.[on explanations by other naturalists of coral-reef building]
 In a recent article in this Review I had occasion to refer to the curious power which is sometimes exercised on behalf of certain accepted opinions, or of some reputed Prophet, in establishing a sort of Reign of Terror in their own behalf, sometimes in philosophy, sometimes in science. This observation was received I expected it to beby those who being themselves subject to this kind of terror are wholly unconscious of the subjection. It is a remarkable illustration of this phenomenon that Mr. John Murray was strongly advised against the publication of his views in derogation of Darwin's long-accepted theory of the coral islands, and was actually induced to delay it for two years. Yet the late Sir Wyville Thomson, who was at the head of the naturalists of the Challenger expedition, was himself convinced by Mr. Murray's reasoning, and the short but clear abstract of it in the second volume of the Narrative of the Voyage has since had the assent of all his colleagues.7
Nor is this the only case, though it is the most important, in which Mr. Murray has had strength to be a great iconoclast. Along with the earlier specimens of deep-sea deposits sent home by naturalists during the first soundings in connection with the Atlantic telegraph cable, there was very often a sort of enveloping slimy mucus in the containing bottles which arrested the attention and excited the curiosity of the specialists to whom they were consigned. It was structureless to all microscopic examination. But so is all the protoplasmic matter of which the lowest animals are formed. Could it be a widely diffused medium of this protoplasmic material, not yet specialised or individualised into organic forms, nor itself yet in a condition to build up inorganic skeletons for a habitation? Here was a grand idea. It would be well to find missing links; but it would be better to find the primordial pabulum out of which all living things had come. The ultra-Darwinian enthusiasts were enchanted. Haeckel clapped his bands and shouted out Eureka loudly. Even the cautious and discriminating mind of Professor Huxley was caught by this new and grand generalisation of the physical basis of life.' It 'was announced by him to the British  Association in 1868. Dr. Will. Carpenter took up the chorus. He spoke of a living expanse of protoplasmic substance,' penetrating with its living substance the whole mass' of the oceanic mud. A fine new Greek name was devised for this mother slime, and it was christened Bathybius,' from the consecrated deeps in which it lay. The conception ran like wildfire through the popular literature of science, and here again there was something like a coming Plebiscite in its favour. Expectant imagination soon played its part. Wonderful movements were seen in this mysterious slime. It became an irregular network,' and it could be seen gradually 'altering its form,' so that entangled granules gradually changed their relative positions. The naturalists of the Challenger' began their voyage in the full Bathybian faith. But the sturdy mind of Mr. John Murray kept its balanceall the more easily since he never could himself find or see any trace of this pelagic protoplasm when the dredges of the Challenger' came fresh from bathysmal bottoms. Again and again he looked for it, but never could he discover it. It always hailed from home. The bottles sent there were reported to yield it in abuirdance, but somehow it seemed to be hatched in them. The laboratory in Jermyn Street was its unfailing source, and the great observer there was its only sponsor. The ocean never yielded it until it had been bottled. At last, one day on board the Challenger' an accident revealed the mystery. One of Mr. Murray's assistants poured a large quantity of spirits of wine into a bottle containing some pure sea-water, when lo! the wonderful protoplasm Bathybius appeared. It was the chemical precipitate of sulphate of lime produced by the mixture of alcohol and sea-water. This was bathos indeed. On this announcement 'Bathybius' disappeared from science, reading us, in more senses than one, a great lesson on precipitation.'10
This is a case in which a ridiculous error and a ridiculous credulity were the direct results of theoretical preconceptions. Bathybius was accepted because of its supposed harmony with Darwins speculations. It is needless to say that Darwin's own theory of the coral islands has no special connection with his later hypotheses of Evolution. Both his theory and the theory of Mr. Murray equally involve the development of changes through the action and interaction of the old agencies of vital, chemical, and mechanical change. Nevertheless the disproof of a theory which was so imposing and had been so long accepted, does read to us the most important lessons. It teaches us that neither the beautynor the imposing characternor the apparent sufficiency of an explanation may be any proof whatever of its truth. And if this be taught us even of explanations which concern results purely physical, comparatively simple, and comparatively definite, how much more is this lesson impressed upon us when, concerning far deeper and more complicated things, explanations are offered which are in themselves obscure, full of metaphor, full of the pitfalls and traps due to the ambiguities of languageexplanations which are incapable of being reduced to proof, and concern both agencies and results of which we are profoundly ignorant.
1 Journal, p. 468.
2 Lyells Principles, 11th edition, p. 585.
3 Journal, ed. 1852, p. 477.
4 Proc. Roy. Soc. Edin., vol. x, pp. 505-18.
7 Narr. Chall. Exp. vol. I, p. 781
8 Proc. Roy. Soc. No. 107, 1868, pp. 190-1.
9 The Depths of the Sea, 2nd ed. London, 1874, pp. 410-15.
10 Narr. Chall. Exp. vol. 1, p. 939.
C. Blinderman & D. Joyce