That Darwin had the application of his theory to the origin of the human species clearly in his mind in 1859, is obvious from a passage in the first edition of "The Origin of Species." (Ed. I, p. 488.) "In the distant future I see open fields for far more important researches. Psychology will be based on a new foundation, that of the necessary acquirement of each mental power and capacity by gradation. Light will be thrown on the origin of man and his history." It is one of the curiosities of scientific literature, that, in the face of this plain declaration, its author should have been charged with concealing his opinions on the subject of the origin of man. But he reserved the full statement of his views until 1871, when the "Descent of Man" was published. The "Expression of the Emotions" (originally intended to form only a chapter in the "Descent of Man") grew into a separate volume, which appeared in 1872. Although always taking a keen interest in geology, Darwin naturally found no time disposable for geological work, even had his health permitted it, after he became seriously engaged with the great problem of species. But the last of his labours is, in some sense, a return to his earliest, inasmuch as it is an expansion of a short paper read before the Geological Society more than forty years before, and, as he says, "revived old geological thoughts" (I, p. 98). In fact, "The Formation of Vegetable Mould through the Action of Worms," affords as striking an example of the great results produced by the long-continued operation of small causes as even the author of the "Principles of Geology" could have desired. In the early months of 1882 Darwin's health underwent a change for the worse; attacks of giddiness and fainting supervened, and on the 19th of April he died. On the 24th, his remains were interred in Westminster Abbey, in accordance with the general feeling that such a man as he should not go to the grave without some public recognition of the greatness of his work. Mr. Darwin became a Fellow of the Royal Society in 1839; one of the Royal Medals was awarded to him in 1853, and he received the Copley Medal in 1864. The "Life and Letters," edited with admirable skill and judgment by Mr. Francis Darwin, gives a full and singularly vivid presentment of his father's personal character, of his mode of work, and of the events of his life. In the present brief obituary notice, the writer has attempted nothing more than to select and put together those facts which enable us to trace the intellectual evolution of one of the greatest of the many great men of science whose names adorn the long roll of the Fellows of the Royal Society. XI ON OUR KNOWLEDGE OF THE CAUSES OF THE PHENOMENA OF ORGANIC NATURE [_Six Lectures to Working Men_.--1863.] I. THE PRESENT CONDITION OF ORGANIC NATURE