The first thorough attempt at a scientific establishment of transformism was made at the beginning of the nineteenth century by the great French scientist Jean Lamarck, the chief opponent of his colleague, Cuvier, at Paris. He had already, in 1802, in his _Observations on Living Organisms_, expressed the new ideas as to the mutability and formation of species, which he thoroughly established in 1809 in the two volumes of his profound work, _Philosophie Zoologique_. In this work he first gave expression to the correct idea, in opposition to the prevalent dogma of fixed species, that the organic "species" is an _artificial abstraction_, a concept of only relative value, like the wider-ranging concepts of genus, family, order, and class. He went on to affirm that all species are changeable, and have arisen from older species in the course of very long periods of time. The common parent forms from which they have descended were originally very simple and lowly organisms. The first and oldest of them arose by abiogenesis. While the type is preserved by _heredity_ in the succession of generations, _adaptation_, on the other hand, effects a constant modification of the species by change of habits and the exercise of the various organs. Even our human organism has arisen in the same natural manner, by gradual transformation, from a group of pithecoid mammals. For all these phenomena--indeed, for all phenomena both in nature and in the mind--Lamarck takes exclusively mechanical, physical, and chemical activities to be the true efficient causes. His magnificent _Philosophie Zoologique_ contains all the elements of a purely monistic system of nature on the basis of evolution. I have fully treated these achievements of Lamarck in the fourth chapter of my _Anthropogeny_, and in the fourth chapter of the _Natural History of Creation_.