each day the work which seemed most necessary, and which he could best do, Darwin managed, in spite of his infirmity of constitution, to complete a larger body of original work, both in experiment and in thought, together with a greater quantity of bibliographical study and collation of observed facts, than any Englishman perhaps has ever done. The valuable book on "Variation" records and systematises a vast number of facts respecting all our principal domestic animals and cultivated plants. It gives evidence of wide reading, as well as great diligence in writing letters of inquiry to all living authorities who could give accurate information. Very many visits were paid to zoological gardens, breeders' establishments, nursery grounds, &c.; and the preparation of skulls, skins, &c., was a frequent occurrence in the Darwinian laboratory. To take the case of rabbits alone, which occupied but a fraction of the time devoted to pigeons: over twenty works are quoted for historical facts, skeletons of various rabbits were prepared and exhaustively compared, the effects of use and disuse of parts traced, most careful measurements are given, and a list of the modifications which domestic rabbits have undergone, with the probable causes, concludes the chapter. As to pigeons, no pigeon-fancier ought to be without the book, for never assuredly was a sporting topic treated by so great a thinker and so admirably. The numerous experiments in crossing different breeds, and the results obtained, make this one of the most instructive books for all breeders. It would seem desirable that this portion of the book should be issued in a separate form. Again, when we turn to the sections on plants we see how indefatigable Darwin was, for he tells us that he cultivated fifty-four varieties of gooseberries alone, and compared them throughout in flower and fruit.