Page:Popular Science Monthly Volume 12.djvu/192

180 a time when there was no life on the earth; that of the strata some are of marine, some of fresh-water formation; that they are often intercalated like leaves in a book, and therefore cannot be referred to any single cataclysm such as the deluge.

From considerations connected with the primary rocks, Leibnitz (1680) had inferred that the earth was once at a far higher temperature than now, and in fact must have been in an ignited state; that it had undergone a gradual cooling. Werner subsequently introduced the Neptunic theory, and Hutton the Plutonic. These cosmographical theories were, however, of less importance than what was done in paleontology. It was discovered that while similar fossil remains extend over vast horizontal surfaces, different fossils are found to succeed each other very rapidly when a vertical examination is made. There is a geological as well as a geographical distribution of plants and animals—geological as to time, geographical as to surface.

In the works of Maillet (1748), and again in those of Buffon, the old doctrine of evolution reappears. A more formal presentment was, however, made by Lamarck in his "Philosophic zoologique," published in 1809. He advocated the doctrine of descent, and announced the propositions now known as Darwinism. According to him, organic forms originated by spontaneous generation, the simplest coming first, and the complex being evolved from them. Variations and transmutations occur through external influences, the environment modifying the organism, and as these in the lapse of time become essential differences, new species arise. Moreover, wants experienced cause the will to develop new organs by the modification of previously-existing ones, and these are transmitted by heredity or generation. Organisms are developed out of one another; so far from being permanent, they have only a temporary existence.

Though an organism tends to be like its progenitor, it will undergo changes by the use or disuse of its parts; by the former it is developed, by the latter deteriorated. The changes produced thus, or by the environment, always have been, and always will be, continuous, not catastrophic.

Lamarck recognized the struggle of each against all. He saw plainly the influence of heredity, and understood the relation of environment and adaptation. He defined in the clearest manner the doctrine of transmutation and theory of descent. According to him, if time enough be allowed, any modification may take place.

So far from meeting with acceptance, the ideas of Lamarck brought upon him ridicule and obloquy. He was as much misrepresented as in former times the Arabian Nature-philosophers had been. The great influence of Cuvier, who had made himself a champion of the doctrine of permanence of species, caused Lamarck's views to be silently ignored, or, if by chance they were referred to, denounced. They were