Bacon (1561-1626) pointed out the evidence for variation in animals and the bearing of this upon the production of new species and upon the gradations of life forms. Descartes (1596 1650) advocated a strong mechanistic concep tion of the physical universe and all life within it. Leibnitz (1646-1716) advocated a doctrine of continuity of life forms, and said that the different classes of animals are so connected by gradatory forms that it was practically impos sible either by observation or imagination to determine where any one begins or ends. These ideas of continuity in nature were also reiterated and strengthened by Spinoza, Pascal and New ton. It is interesting to note that all these con tributions to the establishment of the evolution idea came from the speculative natural philoso phers rather than from the naturalists.
Chief among all the natural philosophers who have attempted to express the early idea of evolution was Kant (1724-1804), but he was staggered by the thought that any human in vestigation could ever reach an understanding of the laws which have governed the derivation of all organic beings from the lowest up to man. °It is quite certain," he wrote, °that we cannot become sufficiently acquainted with organized creatures and their hidden potentialities by the aid of purely mechanical natural principles, much less can we explain them; and this is so certain, that we may boldly assert that it is absurd for man even to conceive such an idea, or to hope that a Newton may one day arise .even to make the production of a blade of grass comprehensible, according to natural laws ordained by no intention. Such an insight we must absolutely deny to man." However, certain naturalists of the 17th and 18th centuries did make their contribu tions of fact, or alleged fact, to the evolu tion idea. For example Bonnet (1720-93), who is reputed to be the author of the term °Evolution" in connection with the de velopment of life, is famous for his extraor dinary °encasement theory" of embryology, ac cording to which all the future progeny and successive after-generations derived from a female animal existed in miniature in the eggs in her body, with lesser eggs within the minia ture young, containing the next generation, and so on ad infinitum.
But it is with the great French naturalist Buffon (1707-88) that the real contribution of naturalists to and participation in the develop ment of the evolution idea importantly begins. He has, indeed, been called by Osborn the naturalist founder of the modern applied form of the evolution theory. But with other his torians of evolution, he has no such standing. Radl, for example, says that "the best thing about Buffon is his style." However it may truthfully be said of him that he was the first great naturalist to point out on a broad scale the mutability of species in relation to changes of environment. Very early in his studies of comparative anatomy he found difficulty in the special creation theory. "The pig does not ap pear to have been formed upon an original special and perfect plan since it is a compound of other animals. It has evidently useless parts, or rather parts of which it cannot make any use, toes, the bones of which are perfectly formed and which nevertheless are of no service to it. Nature is far from subjecting herself to final causes in the formation of her creatures." Buffon believed in the direct modi fying influence of environment. "How many species, being perfected or degenerated by the great changes in land and sea, by the favors or disfavors of nature, by food, by the pro longed influence of climate, are no longer what they formerly were." He also fairly clearly expressed the conception of a struggle for ex istence, an elimination of the least-perfected species and a contest between the fecundity of certain species and their constant destruction.
This is anticipating more or less definitely the prodigality of production ideas of Malthus, and the natural selection doctrine of Darwin. But he was not of the stuff of which martyrs are made. When the authorities of the Church called for an explanation of his views he said: "I declare that I have had no intention of denying the Holy Writ; I declare that I firmly believe all that is written there concerning crea tion, as well concerning the time as the pro cedure; and I willingly retract whatever is in my book that in any way is contradictory of the Mosaic relation, as I hold my hypothesis concerning the formation of the earth and other planets as a purely philosophical It is interesting to note the fact that another great naturalist, Linnzus, exactly contemp0 raneous with Buffon, a botanist, and the first great systematist or classifier of organisms, was an absolute believer in the fixity of species. Species were, in his mind, the units of direct creation; each species bore the impression of the thought of the Creator in all its structure and functions. Later in his life Linnnus did give up, in some little measure, this idea of the special Divine creation and absolute fixity of species. "All the species of one genus," he wrote before his death, "constituted at first a single species, but this subsequently became multiplied by hybrid generations, that is, by in tercrossing with other original species." Following Buffon, the next two most im portant names to be mentioned in connection with the history of evolution are those of Erasmus Darwin (1731-1802), and Lamarck (1744-1829). Erasmus Darwin was a poet and naturalist, and the grandfather of Charles Dar win. He was, in his late years at least, a firm evolutionist, with conceptions concerning the factors or causes of evolution strangely like those afterward proclaimed by Lamarck, and quite opposed to those chiefly insisted on by Charles Darwin. After stating his belief that all organisms have been produced by "one and the same kind of living filament," and setting out strong arguments for the mutability of species, he says: All animals undergo transformations which are in part produced by .their own exer tions, in response to pleasures and pains, and many of these acquired forms or propensities are transmitted to their posterity." This, ac cording to Osborn, is the first clear and defi nite statement of the theory of the transmission of acquired characters as a factor of evolution. He provides against the charge of irreverence in substituting evolution for special creation by saying: "If we may compare infinities, it would seem to require a greater infinity or power to cause the causes of effects, than to cause the effects themselves: that is to establish the laws of creation rather than to directly create." Lamarck may fairly be called the first to set out in detail a full and logical theory of descent with explanations of the causes of this descent. With full justice he is referred to as the most prominent figure in the history of evolution be tween the Greeks and Charles Darwin. But no one has been more misunderstood nor judged with more partiality by over or under praise. He had as contemporaneous antagonist the great anatomist Cuvier (1769-1832) who gave all the heavy weight of his name and position to the attack on the Lamarckian doctrines in particular and evolution in general. Indeed, Cuvier, though he added enormously to our knowledge of comparative anatomy, almost as enormously hindered the progress and post poned the acceptance of the evolution theory, which actually finds a large part of its proof in the facts of comparative anatomy.