my scientific work, such as solving the problem of coral islands, and making out the geological structure of certain islands, for instance, St. Helena. Nor must I pass over the discovery of the singular relations of the animals and plants inhabiting the several islands of the Galapagos Archipelago, and of all of them to the inhabitants of South America. As far as I can judge of myself, I worked to the utmost during the voyage from the mere pleasure of investigation, and from my strong desire to add a few facts to the great mass of facts in natural science. But I was also ambitious to take a fair place among scientific men—whether more ambitious or less so than most of my fellow-workers I can form no opinion."
Among the spoils brought home from the voyage were a number of specimens of fossil edentata, the discovery of which, says Mr. Francis Darwin, "has a special importance as a point in his own life, since it was the vivid impression produced by excavating them with his own hands that formed one of the chief starting-points of his speculation on the origin of species." Recording in July, 1837, the opening of the first note-book on transmutation of species, Darwin refers to the character of the fossils in the Galapagos Archipelago as the origin of all his views. In the early fall of 1837 he made his first observations on earth-worms, on which he based a paper in the Geological Society.
In September, 1838, while busy on his book on volcanoes and coral reefs, he wrote to Mr. Lyell concerning what was to be the grand achievement of his life: "I have lately been sadly tempted to be idle—that is, as far as pure geology is concerned—by the delightful number of new views which have been coming in thickly and steadily—on the classification and affinities and instincts of animals—bearing on the question of species. Note-book after note-book has been filled with facts which begin to group themselves clearly under sub-laws"; and to his cousin, W. D. Fox: "I am delighted to hear you are such a good man as not to have forgotten my questions about the crossing of animals. It is my prime hobby, and I really think some day I shall be able to do something in that most intricate subject, species and varieties." In another letter to Fox, he says: "The smallest contributions thankfully accepted; descriptions of offspring of all crosses between all domestic birds and animals, dogs, cats, etc., very valuable. Don't forget, if your half-breed African cat should die that I should be very much obliged for its carcass sent up in a little hamper for the skeleton; it, or any cross-bred pigeons, fowl, duck, etc., will be more acceptable than the finest haunch of venison or the finest turtle."
His eldest child was born in 1839, and he began upon him the observations which grew into the book on the "Expression of the Emotions." In October, 1846, Darwin informed Hooker that he was about to prepare some papers on the lower marine animals, after which he should begin looking over his ten-year-long accumulation of notes