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( Originally Published Early 1900's )

The establishment of the theory of evolution is generally conceded to be the scientific achievement of the age. It is the natural outcome of modern scientific research and speculation, proceeding as it does from the rapid advance of the physical sciences. Evolution has been defined as a natural history of cosmos including organic beings, ex-pressed in physical terms as a mechanical process.

Primarily evolution is the act of enfolding or unrolling or, in the process of growth, development, as of a flower from a bud or of a bird from an egg. But the term has grown to have other and much larger meanings. It is applied to a system which undertakes to explain the existence of all things inorganic and organic, physical and psychical, including the arts and institutions.

Dim foreshadowings of a theory of evolution were put forth by the early Greek philosophers. Anaximander, Empedocles and Anaxagoras are credited with having caught faint glimmerings of the truth, and it has been maintained that Aristotle, the father of natural history, held opinions as to the causes of diversity in organic beings not unlike those entertained by the geologists of today. However this may be, in the long ages between the days of these speculative Greeks and modern times, there was no development of the theory anticipated by them.

In the Eighteenth Century Linnaeus and Buff on formed conceptions of a progressive organic development, but did little to throw light on the idea. Immanuel Kant; in 1755, published a theory of the mechanical origin of the universe, which was a true nebular cosmogony. Dr.

Erasmus Darwin, the grandfather of Charles Darwin, about 1794, put forth remarkable suggestions pointing to evolution, and the poet Goethe evidently believed evolution to have occurred in the organic world. LaPlace, in 1796, published his "Exposition du Systeme du Monde," in which in a footnote appears his celebrated "nebular hypothesis." But his explanation of his views as to the evolution of the stellar universe and solar and planetary systems belongs to the Nineteenth Century. Thus it was not until this Century that a definite statement of the theory of Evolution appeared. In 1809, Lamarck published his "Philosophie Zoölogique," and in 1815 his "Histoire Naturelle des Animaux sans Vetèbres." In these he framed a distinct hypothesis of the progressive development of animals and plants, setting it forth with an elaborate exposition. Like conclusions were drawn by Geoffrey Saint-Hillaire in his work "Sur le principe de l'unite de composition organique," which appeared in 1828. But the theory of evolution gained few converts. Between the "Philosophie Zoölogique" and the "Origin of the Species" only one volume was devoted entirely to evolution. This was the "Vestiges of the Natural History of Creation," which was published anonymously in England in 1844. Yet in the interval botanists, embryologists and geologists were approaching the theory which astronomy had done so much to prepare men's minds to receive.

The authorship of "Vestiges" is attributed to Robert Chambers. Adopting the Nebular Hypothesis, he passes in review the development of stars and solar systems, presenting a scholarly and skillful exposition of a whole philosophy of cosmic evolution. After outlining the geological history of the earth, he treats of the origin of life from inorganic matter and the development of the animal kingdom through many stages to man, adopting the Aristotelian idea of an internal impulse or tendency towards progression. With much care he shows the reasonableness of his view, arguing that it agrees much better with the known facts of nature in every department of her work than does the idea of a special creation of each distinct species of plant and animal. The book made a great sensation, not unlike that which greeted "The Origin of the Species," fifteen years later. Four editions were issued in the first seven months, and, in nine years, ten editions were exhausted. By 1860 about 24,000 copies were sold.

Early in the Eighteenth Century Linnaeus had announced the result of his study of the stamens and pistils of plants, and by his sexual system opened a new era in the history of botany. He divided plants into sexual and asexual, the former being Phanerogamous or flowering, and the latter Cryptogamous or flowerless. But Linnaeus paid little attention to the functions of plants, and did not advance the study of the embryogenic process. His followers busied themselves with classifying and describing. These branches of botany made great strides and, during the early years of the present Century, the "natural system" gradually displaced the "artificial system" of Linnaeus. The opening up of America, Australia, South Africa and New Zealand to naturalists gave them vast treasures to classify and arrange, and so fully occupied their attention, that it is little to be wondered at that the physiological study of plants was comparatively neglected. In 1815 Trevirnanus called the attention of botanists to the embryo, and in 1823 Amici discovered the existence of pollen tubes. Brogniart and Brown followed in their footsteps, Brown tracing the tubes as far as the nucleus of the ovule. These discoveries laid the foundation of the present science of the embriology of plants.

Robert Brown, Sir William Hooker, John Lindley, and George Bentham are among those who did so much to establish the natural system of classification. In 1830 appeared Lindley's "Introduction to the Natural System of Botany." Sir William Hooker was the author of several works dealing with cryptogamic plants. This investigation was of peculiar importance, for among the various mosses, ferns arid other plants described collectively as "cryptogamic" were numerous types showing intermediate structures bridging over gulfs of difference in organization which might well be thought impassable. Such discoveries were of much value in paving the way for biological evolution.

The man who did more than any other geologist to further the doctrine of evolution was Charles Lyell. In the first part of the Century it was maintained that the earth had undergone a series of catastrophes and revolutions, through the agency of which mountain and vale strata and rock had been formed. As late as 1830 Cuvier's "Essay on the Theory of the Earth" was the accepted authority on geology, and it was generally believed that, as he taught, mountain peaks and ridges "are indications of the violent manner in which they have been elevated." "It is in vain," announced this apostle of the catastrophists, "we search among the powers which now act at the surface of the earth for causes sufficient to produce the revolutions and catastrophes, the traces of which are exhibited in its crust." Thus it was believed that the "revolutions and catastrophes" had been extremely violent, perhaps fatal to all organic life on the globe, and followed by new exercise of creative force. In 1830 appeared the first volume of Lyell's "Principles of Geology," a work which undermined the very foundation of the catastrophe theory. Clearly and convincingly the author showed that the position of Cuvier and his followers was wholly untenable when viewed in the light of the facts of nature. The most ancient formations of the earth were proved to have been formed, ages ago, in the same way and by means of the same physical agencies that are at work to-day.

The views of evolutionists were placed on a scientific basis by the patient labors of biologists, who applied them-selves to the question of the mutability or immutability of species and the extent of variation, as shown by observation. There was a sort of scientific dogma to the effect that species were immutable and, as no tenable account of transmutation was put forward, naturalists refused to relinquish it.

In 1858, two essays were read before the Linnaean Society, one by Charles Darwin, entitled, "On the Tendency of Species to Form Varieties, and on the Perpetuation of Species and Varieties by Means of Natural Selection," and the other by Alfred Russell Wallace, entitled, "On the Tendency of Varieties to Depart from the Original Type." Although these two papers setting forth the same discovery were given to the world at the same time, to Darwin belonged the prior claim. Through years he had been perfecting his theory of Natural Selection. A voyage around the world on the "Beagle," with Captain Fitz-Roy's expedition (1831-1836) gave him remarkable opportunities for pursuing his investigations in natural history, the love for natural history being in his case innate.

He says : "During the voyage of the 'Beagle' I had been deeply impressed by discovering in the Pampean formation great fossil animals covered with armor like that on the existing armadillos; secondly, by the manner in which closely allied animals replace one another in proceeding southwards over the continent ; and, thirdly, by the South American character of most of the productions of the Galapagos Archipelago, and more especially by the manner in which they differ slightly on each island of the group, none of the islands appearing to be very ancient in a geological sense. It was evident that such facts as these, as well as many others, could only be explained on the supposition that species gradually became modified; and the subject haunted me. But it was equally evident that 'none of the evolutionary theories then current in the world' could account for the innumerable cases in which organisms of every kind are beautifully adapted to their habits of life. . . . I had always been much struck by such adaptations, and until these could be explained, it seemed to me almost useless to endeavor to prove by indirect evidence that species have been modified."

This was the starting point. Soon after his return from the voyage Darwin opened, as he says, "his first note-book for facts in relation to the origin of the species, about which I had long reflected, and never ceased working for the next twenty years." By "printed inquiries, by conversations with skillful breeders and gardeners, and by extensive reading," he collected facts, seeming to know intuitively what was necessary to the solving of the problem. Stock breeders were more or less consciously, by selection, improving the domesticated animals and forming new races. Nature must by "selection" form new species, but how did such selection become possible?

"In October, 1838, that is, fifteen months after I had begun my systematic inquiry," says Darwin, "I happened to read for amusement 'Malthus on Population,' and, being well prepared to appreciate the struggle for existence which everywhere goes on, from long continued observations of the habits of plants and animals, it at once struck me that under these circumstances favorable varieties would tend to be preserved and unfavorable ones destroyed. The result of this would be the formation of new species."

Although he now had the clue to the whole subject, not until 1842 did he allow himself to sketch his theory. In the meantime he accumulated pertinent facts with patience and industry, working on the true Baconian principle. In 1842 he made a brief sketch of his theory, elaborating it two years later into an essay of 230 pages. He showed this sketch to Lyell, Hooker and others, but still did not make known to the world his discoveries and conclusions. A letter to his wife, written at this time, charges her, in case he should die, to devote £400 to publishing the essay. But it was long before Darwin, living, was ready to publish it. From 1846 to 1854 he busied himself with preparing an extensive monograph on recent and fossil cirripedes, but in 1856 he began to write out on a large scale a work dealing with the origin of the species. He was interrupted by the arrival of a paper from Alfred Russell Wallace who, far away in the Malay Archipelago, had solved independently the problem to which his friend Dar-win was devoting so much attention.

In 1855 there had appeared an article by Wallace, "On the Law Which Has Regulated the Introduction of New Species." He had deduced the law or generalization that "Every species has come into existence coincident both in Space and Time with a pre-existing closely allied Species," and showed that much was explained by this hypothesis, and that no important facts contradicted it. Three years later, while ill with intermittent fever, he fell to considering the problem of the origin of species. He had read "Malthus on Population" about ten years before, and, recollecting what this author said about the "positive checks" war, disease, accident, famine, etc., which have the effect of keeping savage populations nearly stationary, it flashed upon him that kindred checks must act upon animals, since they increase so rapidly that otherwise their numbers soon would be immense, instead of there being but little variation from year to year. Vaguely pondering on the matter in the intervals of the fever, then came, as if by inspiration, the idea of the survival of the fittest that it must be the weak that perish, while the strongest and best survive. As soon as he was able, Wallace sketched out this theory and sent it by the next post to Darwin.

But for the persuasions of his friends, Hooker and Lyell, Darwin would have generously published Wallace's freshly completed manuscripts, holding back his own, the fruit of so many years of patient investigation and thought. But, yielding to solicitation, "in the interests of science," he accompanied Wallace's essay with one of his own, and the joint communication was read before the society. Thus was the theory of the survival of the fit-test, or of Natural Selection, given to the world.

Before this there had been anticipations of the theory, but they had attracted little attention, and do not seem to have come to the notice of either Wallace or Darwin. The latter, in after years, made a collection of these expressions of thought, giving full credit where credit was due. In 1813 Dr. W. C. Wells read a paper before the London Royal Society, entitled "An Account of a White Female, Part of Whose Skin Resembles That of a Negro." In this he recognizes the principle of Natural Selection as applied to the races of men. In 1831 Patrick Matthew published a work called "Naval Timber and Arboriculture." In the appendix was a brief statement of a theory of the origin of the species, of which Darwin says : "The difference of Mr. Matthew's views from mine are not of much importance," and, "He clearly saw the full force of the principle of Natural Selection." Not contented with this generous acknowledgment of his work, Matthew is said to have gotten out an edition of his book bearing on the title page, after his name, "Discoverer of the Principle of Natural Selection." As Darwin whimsically says, he may be excused for not discovering a theory of Natural Selection in a work on naval timber. In 1822 the Reverend William Herbert, afterwards dean of Westminster, advanced the opinion that "botanical species are only a higher and more permanent class of varieties," and that the same fact is true of animals. Others who expressed views pointing to Natural Selection are Leopold von Buch in 1825, Professor Grant, of Edinburgh; in 1825, Karl Ernst von Baer, in 1828, J. d'Omalius d'Halloy, of Brussels, in 1846, Isidore Geoffroy Saint-Hillaire, in 1850, Franz Unger, in 1852, and Charles Naudin and Herbert Spencer, also in 1852.

On November 24, 1859, Darwin's "Origin of the Species" appeared "an epoch-making book," it is justly called. Its full title is "The Origin of Species by Means of Natural Selection; or the Preservation of Favoured Races in the Struggle for Life." It was received by an outburst of antagonism, and controversy, both scientific and popular, at once began. A month before its publication, Darwin had written to Hooker, "I remember thinking, above a year ago, that if I ever lived to see Lyell, yourself, and Huxley come around, partly by my book and partly by their own reflections, I should feel that the subject is safe, and all the world might rail, but that ultimately the theory of Natural Selection (though, no doubt, imperfect in its present condition, and embracing many errors) would prevail."

Lyell, Hooker and Huxley all "came round." Said Huxley, voicing the sentiment of scientists like himself :

"That which we were looking for and could not find till Darwin and Wallace published their views, was a hypothesis respecting the origin of known organic forms, which involved the operation of no causes but such as could be proved actually at work The 'Origin' provided us with the working hypothesis we sought." So simple was the solution, the key to the "long sought hypothesis," that after mastering it, Huxley exclaimed : "How extremely stupid not to have thought of that be-fore." Huxley's acceptance and advocacy of Darwin's theory did much to influence the public and advance popular opinion. That Darwin appreciated Huxley's indorsement of his work is shown by what he said after his adoption of the theory. "Like a good Catholic who has received extreme unction, I can now sing 'nunc Dimittis.' "

Seven years before the appearance of the "Origin of Species," Herbert Spencer published a skillful and logical essay contrasting the creation and development theories, removing from evolution much of its former vagueness. In 1855, three years before Darwin's and Wallace's essays were read before the Linnaean Society, appeared his "Principles of Psychology," which is based on the theory of evolution. Darwin, Wallace, Spencer, Huxley and Tyndall are called the five great apostles of evolution. Their services to the establishment of the theory were performed in essentially different ways, although Wallace's work, in many respects, resembled that of Darwin. Darwin was an indefatigable collector of facts, with an infinite capacity for taking pains. Little by little he collected data from which might be deduced logically and connectedly the laws and generalizations which he sought. We have seen this in the patience and unwearying labor with which through years he verified his conclusions in biological evolution. Not content with confining himself to the collection of facts testifying to the truth of biological evolution, Wallace was a self-constituted champion of evolution as a whole, valiantly defending it against the attacks of conservatism, making use of his acquaintance with geological phenomena, appreciating the confirmatory evidence found in every field of exploration, and anticipating the new psychology.

Spencer brought to the battle-ground a true philosophical mind and a fund of information justly characterized by John Stuart Mill as "encyclopedic." Gifted with a remarkable power of analysis, a vivid grasp of far-reaching principles, and independence of opinion, Spencer constructed a philosophy of evolution built on a solid basis and covering all things both concrete and abstract.

Huxley was not so broad-minded as his co-laborers, being dogmatic and singularly lacking in spiritual imagination. But he lived up to his creed of "veracity of thought," and never hesitated to avow unpopular conclusions if convinced of their truth.

Tyndall was the orator and physicist of evolution. An Irishman, he was born with intense imagination, a fiery zeal and an eloquent tongue. When Darwin announced his discovery of the cardinal truth of organic evolution, Tyndall championed the cause with all his eloquence and zeal at a time when his support was of especial value, for his brother physicists were standing aloof, as though the question of evolution were no wider in its scope than that of the famous one over which .its battle was first fought —the origin of species. With his scientific knowledge Tyndall combined the ,ability to speak and write plainly to the general public. He was the interpreter of the laws of light and heat and other physical and chemical phenomena, revealing their mysteries to the non-scientific world. His imagination emphasized the spiritual side of his nature and led him to place a value on the unseen which was not felt by Huxley.

We have seen how the term evolution, as used to-day, has two significations, one the widely philosophical, embracing the whole cosmical process, and the other, that of the biologist, expressing the development of organic life. Herbert Spencer, to whom we owe the modern use of the word evolution, insists on a distinction, applying "evolution" to the all-embracing philosophy and "development" to biological processes. Besides his use of "evolution" we are indebted to Spencer for the happy phrase "survival of the fittest," which Darwin adopted and some-times used as an alternative for his own expression, "Natural Selection."

It will be well to review briefly what the, theory and practice of evolution have revealed in various sciences.

In astronomy, the oldest of the sciences, instead of the fixed systems of bygone ages, evolution presents the beautiful nebular hypothesis with its suns and worlds beginning, continuing, disintegrating in the infinitude of space exactly as they have been doing through wons of time. The astronomer watches these vast phenomena and knows he beholds embryonic, existing or dying stars or planets all conforming to physical laws which govern equally stars and atoms. The meteoric hypothesis, which has been revived by Lockyer of late years, substitutes diffused solid meteoric matter at first without heat for the gaseous nebulae of Laplace's hypothesis, and assumes that the heavenly bodies have been formed from the condensations of meteoric clouds; but from a mechanical point of view, if this were true, the evolution of the universe would have taken place very much as though the beginning were gaseous nebulae.

Geology takes our planet and shows how, through millions of years, through gradual and natural agencies, sea and land, mountain and valley, strata and rocks, gravel and clay have been formed; how fire and water and ice performed their part in this wonderful world making; and how kindred processes are going on all around us. She proves that life has existed on the earth for untold ages, exhibiting relics of organic beings buried in rocky layers several miles in thickness. In the lowest strata traces of only the lowest types of life are found. Gradually the fossils of higher forms appear. Fishes follow invertebrates, amphibious animals come after fishes, reptiles succeed mammals and last of all appears man.

Biology studies these fossil forms and finds that the law of growth is from low to high and from simple to complex in accordance with the general principle of evolution.

When classified by the taxonomist all the plant and animal life of the globe resembles a great genealogical tree branching out into infinite ramifications, and it is no insignificant confirmation of the theory of evolution to observe how some fresh light is thrown upon each ramification that has been developed, by each new fossil which is discovered. It is interesting to note that from 1831 to 1881 the number of animals known and described increased from 70,000 to 320,000. At the time of Linnaeus' death only 11,800 species of plants were known; now the number cannot fall short of 100,000.

The study of function has familiarized the student with the phenomena of sex and embryology, of heredity and environment showing the countless modifications under-gone and "the continuous adjustment of internal relations to external relations." It was not until after Darwin's theory of the origin of species and of natural selection had been accepted in its extreme conclusion by Huxley, Spencer, Lyell, Lubbock, Rolle, Haeckel, Canestrini, Francesco, and others that Darwin published "The Descent of Man in Relation to sex." In America Asa Gray was one of the first to support Darwin's theory.

Gathering data from every available source, studying the adult as well as the infant mind, the mind diseased and the mind in perfect health, the psychology of to-day, tentative and speculative though it may be, shows that its phenomena are governed by the same laws as the concrete world. The psychologists find the same difficulty in bridging over the gulf between the psychic and the physical life and functions that biologists have in deriving the organic from the inorganic. But Herbert Spencer has demonstrated that the preliminary sciences of physics and biology furnish many suggestions for the study of psychology.

Anthropology shows man developing from a rude and untutored savage, covered with fur, with canine teeth, and bestial habits, living on raw meat and uncooked roots which he dug from the earth with his hands, hiding from his enemies in a cave or roosting in a hollow tree, with no language save inarticulate cries of rage, pain or passion, a creature compared to whom the bushman of South Africa or Digger Indian of the West is a civilized human being. It shows the gradual growth of customs, institutions, arts and sciences, and the history of races, nations and individuals all conforming to the laws of evolution.

And so in every science has evolution lent its aid, for while many authorities refuse to accept it in all its details, it is none the less used universally as a working basis.

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