The association of iron with Mars probably influenced the early chemical physicians in their adoption of iron salts in anæmic complaints, and as general tonics. The undoubted effect of iron remedies in chlorotic disease was naturally observed, and the reputation of the metal was established for the treatment of this condition long before it was discovered that iron is an invariable constituent of the human body. When this physiological fact came to be recognised it was supposed that the action of iron salts was explained; but, in fact, the investigations of the last century have only tended to make this theory doubtful. It is known that in health the proportion of iron in the body is fairly constant. An average man’s blood contains about 38 grains, almost all of which is contained in the hæmoglobin. He requires from one to two grains every day to make up for waste, and this he gets in the meat and vegetable food which he absorbs. The vegetables obtain iron from the soil, and animals acquire it from the corn, roots, or grasses which they eat. So far as is known it is from these sources only that human beings assimilate the iron they require. It is very doubtful whether a particle of the iron administered in any of the multitudinous forms which pharmacy provides is retained. A noted modern physiologist, Kletzinsky, says “From all the hundredweights of iron given to anæmics and chlorotics during centuries not a single blood corpuscle has been formed.” For all that there is no medical practitioner of any considerable experience who has not found directly beneficial results follow the administration of these medicines in such cases.