Although the philosophical writers of classical times obtained a few glimpses of the action of law in nature regulating its successive changes, nothing satisfactory could be effected till the actual facts had been better ascertained by the whole body of workers who, during the last five centuries, have penetrated ever more and more deeply into nature’s mysteries and laws. By their labors we became possessed of such a body of carefully observed facts that, towards the end of the eighteenth century, such thinkers as Laplace and Hutton were enabled to give us the first rudiments of theories of evolution as applied to the solar system and the earth’s crust, both of which have been greatly developed and rendered more secure during the century just passed away. In like manner Buffon and Goethe may be said to have started the idea of organic evolution, more systematically treated a little later by Lamarck, but still without any discovery of laws adequate to produce the results we see everywhere in nature. The subject then languished, till, after twenty years of observation and research, Charles Darwin produced a work which at once satisfied many thinkers that the long-desired clew had been discovered. Its acceptance by almost the whole scientific world soon followed: it threw new light on almost every branch of research, and it will probably take its place, in the opinion of future generations, as the crowning achievement of the nineteenth century. ALFRED RUSSEL WALLACE. CHEMISTRY