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 having used a “variety of animals,” whose living breasts and pericardia he opened, and if he had lived in these days he would, perhaps, have met with scant mercy from a Royal Commission on Vivisection. And yet, without that, would the circulation have been discovered? But the work on Generation shows even still more his power of really intense and continuous observation. What marvellous industry and indefatigable search after facts! And this disposition must have commenced extremely early, for he had made all his numerous experiments on the circulation before he was thirty-seven, and must have lasted to extreme old age, for he was still observing the movements of the stars or the growth of plants up to the time of death, when he was nearly eighty years of age. A usual peculiarity of this class of mind is the great ingenuity and imagination men show in arranging their experiments and in devising new ones. Every one must have admired the ingenious mechanism by which physical hypotheses are tested or proved; we may