IX

THE DEBT OF SCIENCE TO DARWIN 1

The Century before Darwin-The Voyage of the Beagle-The Journal of Researches Studies of Domestic Animals-Studies of Cultivated and Wild Plants-Researches on the Cowslip, Primrose, and Loosestrife -The Struggle for Existence-Geographical Distribution and Dispersal of Organisms-The Descent of Man and Later Works-Estimate of Darwin's Life-Work.

THE great man recently taken from us had achieved an amount of reputation and honour perhaps never before accorded to a contemporary writer on science. His name has given a new word to several languages, and his genius is acknowledged wherever civilisation extends. Yet the very greatness of his fame, together with the number, variety, and scientific importance of his works, has caused him to be altogether misapprehended by the bulk of the reading public. Every book of Darwin's has been reviewed or noticed in almost every newspaper and periodical, while his theories have been the subject of so much criticism and so much dispute, that most educated persons have been able to obtain some general notion of his teachings, often without having read a single chapter of his works, and very few, indeed, except professed students of science, have read the whole series of them. It has been so easy to learn something of the Darwinian theory at second-hand that few have cared to study it as expounded by its author.

It thus happens that, while Darwin's name and fame are more widely known than in the case of any other modern man of science, the real character and importance of the work he did are as widely misunderstood. The best scientific

1 This article appeared in the Century Magazine of January 1883.

authorities rank him far above the greatest names in natural science-above Linnæus and Cuvier, the great teachers of a past generation-above De Candolle and Agassiz, Owen and Huxley, in our own times. Many must feel inclined to ask,What is the secret of this lofty pre-eminence so freely accorded to a contemporary by his fellow-workers? What has Darwin done, that even those who most strongly oppose his theories rarely suggest that he is overrated? Why is it universally felt that the only name with which his can be compared in the whole domain of science is that of the illustrious Newton?

It will be my endeavour in the present chapter to answer these questions, however imperfectly, by giving a connected sketch of the work which Darwin did, the discoveries which he made, the new fields of research which he opened up, the new conceptions of nature which he has given us. Such a sketch may help to clear away some of the obscurity which undoubtedly prevails as to the cause and foundation of Darwin's pre-eminence.

In order to understand the vast and fundamental change effected by the publication of Darwin's most important volume-The Origin of Species-we must take a hasty glance at the progress of the science of natural history during the preceding century.

The Century before Darwin

Almost exactly a hundred years before Darwin we find Linnæus and his numerous disciples hard at work describing and naming all animals and plants then discovered, and classifying them according to the artificial method of the great master, which is still known as the Linnæan System; and from that time to the present day a large proportion of naturalists are fully occupied with this labour of describing new species and new genera, and in classifying them according to the improved and more natural systems which have been gradually introduced.

But another body of students have always been dissatisfied with this superficial mode of studying externals only, and have devoted themselves to a minute examination of the internal structure of animals and plants; and early in this century the great Cuvier showed how this knowledge of

anatomy could be applied to the classification of animals according to their whole organisation in a far more natural manner than by the easier method of Linnæus. Later on, when improved microscopes and refined optical and chemical tests became available, the study of anatomy was carried beyond the knowledge of the parts and organs of the bodysuch as bones, muscles, blood-vessels, and nerves to the investigation of the tissues, fibres, and cells of which these are composed; while the physiologists devoted themselves to an inquiry into the mode of action of this complex machinery, so as to discover the use of every part, the nature of its functions in health and disease, and, as far as possible, the nature of the forces which kept them all in action.

Down to the middle of the present century the study of nature advanced with giant strides along these separate lines of research, while the vastness and complexity of the subject led to a constantly increasing specialisation and division of labour among naturalists, the result being that each group of inquirers came to look upon his own department as more or less independent of all the others, each seemed to think that any addition to his body of facts was an end in itself, and that any bearing these facts might have on other branches of the study or on the various speculations as to the "system of nature" or the "true method of classification" that had at various times been put forth was an altogether subordinate and unimportant matter. And, in fact, they could hardly think otherwise. For, while there was much talk of the "unity of nature," a dogma pervaded the whole scientific world which rendered hopeless any attempt to discover this supposed unity amid the endless diversity of organic forms and structures, while so much of it as might be detected would necessarily be speculative and unfruitful. This dogma was that of the original diversity and permanent stability of species, a dogma which the rising generation of naturalists must find it hard to believe was actually held, almost universally, by the great men they look up to as masters in their several departments, and held for the most part with an unreasoning tenacity and scornful arrogance more suited to politicians or theologians than to men of science. Although the doctrine of the special and independent creation of every

species that now exists or ever has existed on the globe was known to involve difficulties and contradictions of the most serious nature, although it was seen that many of the facts revealed by comparative anatomy, by embryology, by geographical distribution, and by geological succession were utterly unmeaning and even misleading, in view of it; yet, down to the period we have named, it may be fairly stated that nine-tenths of the students of nature unhesitatingly accepted it as literally true, while the other tenth, though hesitating as to the actual independent creation, were none the less decided in rejecting utterly and scornfully the views elaborated by Lamarck, by Geoffroy St. Hilaire, and at a much later date by the anonymous author of the Vestiges of Creation that every living thing had been produced by some modification of ordinary generation from parents more or less closely resembling it. Holding such views of the absolute independence of each species, it almost necessarily followed that the only aspect of nature of which we could hope to acquire complete and satisfactory knowledge was that which regarded the species itself. This we could describe in the minutest detail; we could determine its range in space and in time; we could investigate its embryology from the rudimental germ, or even from the primitive cell, up to the perfect animal or plant; we could learn every point in its internal structure, and we might hope, by patient research and experiment, to comprehend the use, function, and mode of action of every tissue and fibre, and ultimately of each cell and organic unit. All this was real knowledge, was solid fact. But, so soon as we attempted to find out the relations of distinct species to each other, we embarked on a sea of speculation. We could, indeed, state how one species differed from another species in every particular of which we had knowledge; but we could draw no sound inferences as to the reason or cause of such differences or resemblances, except by claiming to know the very object and meaning of the creator in producing such diversity. And, in point of fact, the chief inference that was drawn is now proved to be erroneous. was generally assumed, as almost self-evident, that the ultimate cause of the differences in the forms, structures, and habits of the organic productions of different countries, was

It

that each species inhabiting a country was specially adapted to the physical conditions that prevailed there, to which it was exactly fitted. Even if this theory had been true, it was an unproductive ultimate fact, for it was never pretended that we could discover any reason for the limitation of humming-birds and cactuses to America, of hippopotami to Africa, or of kangaroos and gum-trees to Australia; and we were obliged to believe either that these countries possessed hidden peculiarities of climate or other conditions, or that this was only one out of many unknown and unknowable causes determining the special action of the creative power. All this was felt to be so unsatisfactory that the majority of naturalists openly declared that their sole business was to accumulate facts, and that any attempt to co-ordinate these facts and see what inferences could be drawn from them was

altogether premature. In this frame of mind, year after year passed away, adding its quota to the vast mass of undigested facts which were accumulating in every branch of the science. The remotest parts of the globe were ransacked to add to the treasures of our museums, and the number of known species became so enormous that students began to confine themselves not merely to single classes, as birds or insects, but to single orders, as beetles or land-shells, or even to smaller groups, as weevils or butterflies. All, too, were so impressed with the belief in the reality and permanence of species, that endless labour was bestowed on the attempt to distinguish them-a task whose hopelessness may be inferred from the fact that, even in the well-known British flora, one authority describes sixty-two species of brambles and roses, another of equal eminence only ten species of the same groups; and it is by no means uncommon for two, five, or even ten species of one author to be classed as a single species by another. All this time geologists had been so assiduously at work in the discovery of organic remains that the extinct species often equalled, and, in some groupsas the Mollusca-very far exceeded, those now living on the earth, and these were all found to belong to the very same classes and orders as the living forms, and to form part of one great system. Much attention was now paid to the geological succession of the different groups of animals, which