In May, 1928, Hart, Steenbock, Waddell and Elvehjem1 reported a series of observations on the rat in which they showed that iron was inadequate to bring about regeneration of hemoglobin, but on the addition of a small amount of copper regeneration took place rapidly. The importance of the rôle of copper as an adjunct to iron was discovered only after careful elimination of other possible factors. Since then they2 have shown conclusively that copper plays a unique part in hemoglobin response.
McHargue, Healy and Hill3 state that copper has an important function in the formation of hemoglobin.
Elden, Sperry, Robscheit-Robbins and Whipple4 admit that certain metals and their salts when added to the standard diet have a distinct influence and increase the production of hemoglobin. The feeding of copper and iron combined may at times have an unusually favorable effect or again may not exceed the