III.—MONISTIC BIOGENY
The third phase of the evolution of the world opens with the advent of organisms on our planet, and continues uninterrupted from that point until the present day. The great problems which this most interesting part of the earth’s history suggests to us were still thought insoluble at the beginning of the nineteenth century, or, at least, so difficult that their solution seemed to be extremely remote. Now, at the close of the century, we can affirm with legitimate pride that they have been substantially solved by modern biology and its theory of transformism; indeed, many of the phenomena of the organic world are now interpreted on physical principles as completely as the familiar physical phenomena of inorganic nature. The merit of making the first important step in this difficult path and of pointing out the way to the monistic solution of all the problems of biology must be accorded to the great French scientist, Jean Lamarck; it was in 1809, the year of the birth of Charles Darwin, that he published his famous Philosophie Zoologique. In this original work not only is a splendid effort made to interpret all the phenomena of organic life from a monistic and physical point of view, but the path is opened which alone leads to the solution of the greatest enigma of this branch of science—the problem of the natural origin of organic species. Lamarck, who had an equally extensive empirical acquaintance with zoology and botany, drew the first sketch of the theory of descent; he showed that all the countless members of the plant and animal kingdoms have arisen by slow transformation from simple, common ancestral types, and that it is the gradual modification of forms by adaptation, in reciprocal action with heredity, which has brought about this secular metamorphosis.
I have fully appreciated the merit of Lamarck in the fifth chapter, and of Darwin in the sixth and seventh chapters, of the Natural History of Creation. Darwin, fifty years afterwards, not only gave a solid foundation to all the essential parts of the theory of descent, but he filled up the lacunae of Lamarck’s work by his theory of selection. Darwin reaped abundantly the success that Lamarck had never seen, with all his merit. His epoch-making work on The Origin of Species by Natural Selection has transformed modern biology from its very foundations, in the course of the last forty years, and has raised it to a stage of development that yields to no other science in existence. Darwin is the Copernicus of the organic world, as I said in 1868, and E. du Bois-Reymond repeated fifteen years afterwards.[27]