Manganese was introduced into practice mainly by M. Hannon, of Brussels, with special reference to the treatment of these conditions. He argued that, during digestion, sulphuretted hydrogen is formed, and reacts on the ferrous and manganic compounds contained in the intestines, changing them into insoluble sulphides, and thus removing essential elements of haematosin. This happens especially (he supposes) in chlorosis, and the remedy is to supply more of a metal which can form such sulphides, and prevent the removal of essential elements of the organism. Hence, bismuth, lead, and copper are said to prove as serviceable as iron or manganese, though the latter are better assimilated (Presse Medicale Belge, 1850, and Guibert). M. Hannon goes even further than this, and describes three forms of chlorosis, according as there is a deficiency in the blood of iron only, of manganese only, or of both metals. Thus, in the first case, there are "earthy tint of skin, weakness of locomotor system, slow, regular pulse, diarrhoea, and fluid menstrual discharge." In the second case, "color of skin and mucous membranes normal, pain in muscles, constipation, amenorrhoea." In the third case, "waxy tint, bluish sclerotics, oedema, serious nerve-disturbance, derangement of circulation, dyspnoea, low temperature, uterine pain." According to such symptoms does he recommend either iron alone, manganese alone, or a combination of both metals. It is evident that these statements are largely theoretical; and, apart from the fact that even the necessary presence of manganese in the blood of healthy persons is doubtful, an appeal to clinical results does not bear out the suggestion of its great importance as a haematinic remedy - rather the contrary. M. Hannon himself reported very good effects from it, and Dr. Steer (Cheltenham) saw benefit in chlorotic anaemia, traumatic anaemia, and in phthisis, and in anaemia of children; but he used saccharated carbonate of manganese with iron, not manganese alone. In uterine leu-corrhoea of pale weakly subjects, he gave it with ergot; for constipation, with aloes; for dyspepsia, with soda and rhubarb (Medical Times, ii., 1853). Sir J. Simpson found the phosphate sometimes useful in amenor-rhoea, given either with or without iron, but says very little about it (Medical Times, i., 1861, p. 517). Dr. Broadbent, using the chloride and sulphate, reported some favorable, some negative, results. Mr. Carter used it with no good effect ("Clinical Society's Transactions"), while Dr. Garrod failed to cure every case of anaemia in which he employed the manganese salts alone, and the subsequent administration of iron was always followed by rapid improvement. It is true that M. Petrequin was an enthusiastic advocate for the remedy in all forms of impaired blood-condition, including intermittent fever, phthisis, and cancer, but the general experience of the profession is not with him or M. Hannon. All we can at present say is, that in obstinate cases of chlorosis not cured by iron, the conjunction with manganese should receive further trial.