The iron needed for the making of hæmoglobin is obtained both from meat and vegetables. The constituents of an ordinary diet provide from 2 to 3 centigrammes of iron a day. The whole of the blood contains about 4·5 grammes. When corpuscles are being destroyed in the spleen, the iron which their pigment contains is largely reabsorbed and rendered available for further use. The iron in a mixed diet is more than sufficient to counterbalance any loss. Milk contains extremely little iron. Before birth the liver and spleen accumulate a store of iron which lasts until the end of the nursing period, unless this be unduly prolonged. If it be prolonged, the child is apt to become anæmic. Iron has been administered in the treatment of anæmia ever since its presence in the red clot of blood was recognized a hundred and fifty years ago. Physicians are agreed that in the anæmia of young people it is of value; but observations made with a view to obtaining definite data as to the increase in number of blood-corpuscles which results from the administration of iron, without any other alteration in the diet or the habits of the patient, have not given accordant results. Some observers have obtained an increase with organic compounds of iron, others with inorganic compounds; some are in favour of small doses, others of very large ones. As in the treatment by drugs of other abnormal conditions, it is difficult to isolate the effect of the drug from the effects of improvements in the general regimen. Yet physicians agree that iron accentuates the beneficial effects of fresh air and improved diet.