Far abler men than myself may confess, that they have not that untiring patience in accumulating, and that wonderful skill in using, large masses of facts of the most varied kind, — that wide and accurate physiological knowledge, — that acuteness in devising and skill in carrying out experiments, — and that admirable style of composition, at once clear, persuasive and judicial, — qualities, which in their harmonious combination, mark out Mr. Darwin as the man, perhaps of all men now living, best fitted for the great work he has undertaken and accomplished.