Struck by Wegner's observations on bone-changes under phosphorus, and following up the paper of Maas, "On the Influence of Arsenic in Bone-growth, and its Value in Surgical Therapeutics" (1872), Th. Gies has recently published some careful and interesting experiments which well illustrate such influence (Archiv fur Exper. Path., etc., Bd. viii., Hft. iii., December, 1877). Using at first young rabbits badly nourished, he found that arsenic destroyed them without causing bone-change; but having, by careful food, secured for fresh animals apparently more resisting power, the same daily doses (0.005 to 0.002 gramme arsenious acid) continued for nineteen to thirty-four days, seemed to improve their condition, as compared with rabbits from the same litter, and fed in the same manner (but without arsenic): the former were larger, heavier, with clearer skin, and healthier-looking than the latter, and after death the respective bones could be at once distinguished. In the long bones of the arsenic-eaters was a special thick layer (arsen-schichte) of bone between the epiphysis and the shaft; the shaft also was thicker, and in bones, such as the ribs and the vertebrae, the structure was much more dense, and harder to divide, than in normal animals; the new structure was true bone, but the bone-corpuscles and Haversian canals were smaller than the average. Comparative experiments were made with many rabbits, cocks, and pigs, and in such manner as to leave no doubt whatever that increased growth and condensation of bony tissue were traceable to the action of arsenic. In old animals, where epiphyseal growth had ceased, increase of thickness of bones occurred: on the other hand, if the doses were increased beyond a certain point, resorption of bone occurred, and symptoms of poisoning set in. Bones purposely fractured had not united under the treatment, for their small size made it impossible to keep them in position, but a false joint formed, and much callus was round the broken ends; there was fatty degeneration of all internal organs. Gies does not adopt Wegner's view of increased stimulus given to bone-formation, but rather that of Cunze and Lolliot, that arsenic diminishes tissue-change, especially as regards carbohydrates, and hence follow increased deposit and insufficient removal of organic particles.