Volume IV Part 9 (1/2)

NEW CHAMPIONS

To the Origin of Species, then, and to its author, Charles Darwin, must always be ascribed chief credit for that vast revolution in the fundamental beliefs of our race which has come about since 1859, and which made the second half of the century memorable. But it must not be overlooked that no such sudden metamorphosis could have been effected had it not been for the aid of a few notable lieutenants, who rallied to the standards of the leader immediately after the publication of the Origin. Darwin had all along felt the utmost confidence in the ultimate triumph of his ideas. ”Our posterity,” he declared, in a letter to Hooker, ”will marvel as much about the current belief (in special creation) as we do about fossil sh.e.l.ls having been thought to be created as we now see them.” But he fully realized that for the present success of his theory of trans.m.u.tation the champions.h.i.+p of a few leaders of science was all-essential. He felt that if he could make converts of Hooker and Lyell and of Thomas Henry Huxley at once, all would be well.

His success in this regard, as in others, exceeded his expectations.

Hooker was an ardent disciple from reading the proof-sheets before the book was published; Lyell renounced his former beliefs and fell into line a few months later; while Huxley, so soon as he had mastered the central idea of natural selection, marvelled that so simple yet all-potent a thought had escaped him so long, and then rushed eagerly into the fray, wielding the keenest dialectic blade that was drawn during the entire controversy. Then, too, unexpected recruits were found in Sir John Lubbock and John Tyndall, who carried the war eagerly into their respective territories; while Herbert Spencer, who had advocated a doctrine of trans.m.u.tation on philosophic grounds some years before Darwin published the key to the mystery--and who himself had barely escaped independent discovery of that key--lent his masterful influence to the cause. In America the famous botanist Asa Gray, who had long been a correspondent of Darwin's but whose advocacy of the new theory had not been antic.i.p.ated, became an ardent propagandist; while in Germany Ernst Heinrich Haeckel, the youthful but already noted zoologist, took up the fight with equal enthusiasm.

Against these few doughty champions--with here and there another of less general renown--was arrayed, at the outset, practically all Christendom.

The interest of the question came home to every person of intelligence, whatever his calling, and the more deeply as it became more and more clear how far-reaching are the real bearings of the doctrine of natural selection. Soon it was seen that should the doctrine of the survival of the favored races through the struggle for existence win, there must come with it as radical a change in man's estimate of his own position as had come in the day when, through the efforts of Copernicus and Galileo, the world was dethroned from its supposed central position in the universe. The whole conservative majority of mankind recoiled from this necessity with horror. And this conservative majority included not laymen merely, but a vast preponderance of the leaders of science also.

With the open-minded minority, on the other hand, the theory of natural selection made its way by leaps and bounds. Its delightful simplicity--which at first sight made it seem neither new nor important--coupled with the marvellous comprehensiveness of its implications, gave it a hold on the imagination, and secured it a hearing where other theories of trans.m.u.tation of species had been utterly scorned. Men who had found Lamarck's conception of change through voluntary effort ridiculous, and the vaporings of the Vestiges altogether despicable, men whose scientific cautions held them back from Spencer's deductive argument, took eager hold of that tangible, ever-present principle of natural selection, and were led on and on to its goal. Hour by hour the att.i.tude of the thinking world towards this new principle changed; never before was so great a revolution wrought so suddenly.

Nor was this merely because ”the times were ripe” or ”men's minds prepared for evolution.” Darwin himself bears witness that this was not altogether so. All through the years in which he brooded this theory he sounded his scientific friends, and could find among them not one who acknowledged a doctrine of trans.m.u.tation. The reaction from the stand-point of Lamarck and Erasmus Darwin and Goethe had been complete, and when Charles Darwin avowed his own conviction he expected always to have it met with ridicule or contempt. In 1857 there was but one man speaking with any large degree of authority in the world who openly avowed a belief in trans.m.u.tation of species--that man being Herbert Spencer. But the Origin of Species came, as Huxley has said, like a flash in the darkness, enabling the benighted voyager to see the way.

The score of years during which its author had waited and worked had been years well spent. Darwin had become, as he himself says, a veritable Croesus, ”overwhelmed with his riches in facts”--facts of zoology, of selective artificial breeding, of geographical distribution of animals, of embryology, of paleontology. He had ma.s.sed his facts about his theory, condensed them and recondensed, until his volume of five hundred pages was an encyclopaedia in scope. During those long years of musing he had thought out almost every conceivable objection to his theory, and in his book every such objection was stated with fullest force and candor, together with such reply as the facts at command might dictate. It was the force of those twenty years of effort of a master-mind that made the sudden breach in the breaswtork{sic} of current thought.

Once this breach was effected the work of conquest went rapidly on. Day by day squads of the enemy capitulated and struck their arms. By the time another score of years had pa.s.sed the doctrine of evolution had become the working hypothesis of the scientific world. The revolution had been effected.

And from amid the wreckage of opinion and belief stands forth the figure of Charles Darwin, calm, imperturbable, serene; scatheless to ridicule, contumely, abuse; unspoiled by ultimate success; unsullied alike by the strife and the victory--take him for all in all, for character, for intellect, for what he was and what he did, perhaps the most Socratic figure of the century. When, in 1882, he died, friend and foe alike conceded that one of the greatest sons of men had rested from his labors, and all the world felt it fitting that the remains of Charles Darwin should be entombed in Westminster Abbey close beside the honored grave of Isaac Newton. Nor were there many who would dispute the justice of Huxley's estimate of his accomplishment: ”He found a great truth trodden under foot. Reviled by bigots, and ridiculed by all the world, he lived long enough to see it, chiefly by his own efforts, irrefragably established in science, inseparably incorporated with the common thoughts of men, and only hated and feared by those who would revile but dare not.”

THE ORIGIN OF THE FITTEST

Wide as are the implications of the great truth which Darwin and his co-workers established, however, it leaves quite untouched the problem of the origin of those ”favored variations” upon which it operates.

That such variations are due to fixed and determinate causes no one understood better than Darwin; but in his original exposition of his doctrine he made no a.s.sumption as to what these causes are. He accepted the observed fact of variation--as constantly witnessed, for example, in the differences between parents and offspring--and went ahead from this a.s.sumption.

But as soon as the validity of the principle of natural selection came to be acknowledged speculators began to search for the explanation of those variations which, for purposes of argument, had been provisionally called ”spontaneous.” Herbert Spencer had all along dwelt on this phase of the subject, expounding the Lamarckian conceptions of the direct influence of the environment (an idea which had especially appealed to Buffon and to Geoffroy Saint-Hilaire), and of effort in response to environment and stimulus as modifying the individual organism, and thus supplying the basis for the operation of natural selection. Haeckel also became an advocate of this idea, and presently there arose a so-called school of neo-Lamarckians, which developed particular strength and prominence in America under the leaders.h.i.+p of Professors A. Hyatt and E.

D. Cope.

But just as the tide of opinion was turning strongly in this direction, an utterly unexpected obstacle appeared in the form of the theory of Professor August Weismann, put forward in 1883, which antagonized the Lamarckian conception (though not touching the Darwinian, of which Weismann is a firm upholder) by denying that individual variations, however acquired by the mature organism, are transmissible. The flurry which this denial created has not yet altogether subsided, but subsequent observations seem to show that it was quite disproportionate to the real merits of the case. Notwithstanding Professor Weismann's objections, the balance of evidence appears to favor the view that the Lamarckian factor of acquired variations stands as the complement of the Darwinian factor of natural selection in effecting the trans.m.u.tation of species.

Even though this partial explanation of what Professor Cope calls the ”origin of the fittest” be accepted, there still remains one great life problem which the doctrine of evolution does not touch. The origin of species, genera, orders, and cla.s.ses of beings through endless trans.m.u.tations is in a sense explained; but what of the first term of this long series? Whence came that primordial organism whose trans.m.u.ted descendants make up the existing faunas and floras of the globe?

There was a time, soon after the doctrine of evolution gained a hearing, when the answer to that question seemed to some scientists of authority to have been given by experiment. Recurring to a former belief, and repeating some earlier experiments, the director of the Museum of Natural History at Rouen, M. F. A. Pouchet, reached the conclusion that organic beings are spontaneously generated about us constantly, in the familiar processes of putrefaction, which were known to be due to the agency of microscopic bacteria. But in 1862 Louis Pasteur proved that this seeming spontaneous generation is in reality due to the existence of germs in the air. Notwithstanding the conclusiveness of these experiments, the claims of Pouchet were revived in England ten years later by Professor Bastian; but then the experiments of John Tyndall, fully corroborating the results of Pasteur, gave a final quietus to the claim of ”spontaneous generation” as. .h.i.therto formulated.

There for the moment the matter rests. But the end is not yet. Fauna and flora are here, and, thanks to Lamarck and Wallace and Darwin, their development, through the operation of those ”secondary causes” which we call laws of nature, has been proximally explained. The lowest forms of life have been linked with the highest in unbroken chains of descent.

Meantime, through the efforts of chemists and biologists, the gap between the inorganic and the organic worlds, which once seemed almost infinite, has been constantly narrowed. Already philosophy can throw a bridge across that gap. But inductive science, which builds its own bridges, has not yet spanned the chasm, small though it appear. Until it shall have done so, the bridge of organic evolution is not quite complete; yet even as it stands to-day it is perhaps the most stupendous scientific structure of the nineteenth century.

VII. EIGHTEENTH-CENTURY MEDICINE

THE SYSTEM OF BOERHAAVE

At least two pupils of William Harvey distinguished themselves in medicine, Giorgio Baglivi (1669-1707), who has been called the ”Italian Sydenham,” and Hermann Boerhaave (1668-1738). The work of Baglivi was hardly begun before his early death removed one of the most promising of the early eighteenth-century physicians. Like Boerhaave, he represents a type of skilled, practical clinitian rather than the abstract scientist.

One of his contributions to medical literature is the first accurate description of typhoid, or, as he calls it, mesenteric fever.

If for nothing else, Boerhaave must always be remembered as the teacher of Von Haller, but in his own day he was the widest known and the most popular teacher in the medical world. He was the idol of his pupils at Leyden, who flocked to his lectures in such numbers that it became necessary to ”tear down the walls of Leyden to accommodate them.” His fame extended not only all over Europe but to Asia, North America, and even into South America. A letter sent him from China was addressed to ”Boerhaave in Europe.” His teachings represent the best medical knowledge of his day, a high standard of morality, and a keen appreciation of the value of observation; and it was through such teachings imparted to his pupils and advanced by them, rather than to any new discoveries, that his name is important in medical history. His arrangement and cla.s.sification of the different branches of medicine are interesting as representing the att.i.tude of the medical profession towards these various branches at that time.