Of course the 'Origin of Species' was largely translated at once into all the civilised languages of Europe, Russian as well as French, Dutch as well as German, Swedish as well as Italian, Spanish as well as Hungarian, nay even, at last, transcending narrow continental limits, Japanese as well as Hindustani. The revolution which it was rapidly effecting was indeed a revolution in every mode of thought and feeling as well as a revolution in mere restricted biological opinion. But all this time, the modest, single-minded, and unassuming author was working unmoved among his plants and pigeons in his home at Down, regardless of the European fame he was so quickly acquiring, and anxious only to bring to a termination the vast work which he still contemplated. A little more than eleven years intervened between the publication of the 'Origin of Species,' in 1859, and the first appearance of the 'Descent of Man,' in 1871. The interval was occupied in carrying out in part the gigantic scheme of his original collections for the full treatment of the development theory. The work published in 1859 Darwin regarded merely as an abstract and preliminary outline of his full opinions: 'No one can feel more sensible than I do,' he wrote, 'of the necessity of hereafter publishing in detail all the facts, with references, on which my conclusions have been grounded.' The marvellously learned work on the 'Variation of Animals and Plants under Domestication,' which came out in two volumes in 1867, formed the first instalment of this long-projected treatise. The second part, as he told Mr. Fiske, was to have treated of the variation of animals and plants through natural selection; while the third part would have dealt at length with the phenomena of morphology, of classification, and of distribution in space and time. But these latter portions of the work were never written. To say the truth, they were never needed. So universal was the recognition among the younger men of Darwin's discovery, that before ten years were over innumerable workers were pushing out the consequences of natural selection into every field of biology and palæontology. It seemed no longer so necessary as it had once seemed to write the larger and more elaborate treatise he had originally contemplated.