Studies on "Trace Elements" in the Blood, especially with Regard to the Occurrence of Copper and Zinc (a preliminary paper)

By far the majority of studies and speculations on metabolism in man and animals have been concerned with the fate of proteins, fats, and carbohydrates. Even when interest was awakened in enzymes and vitamins, the transformation of the organic substances was still studied. Gradually, however, various methods of the analysis and measuring instruments used have been so perfected that other problems can now be included in the field of biological and medical researches, namely, the significance of inorganic substances for the living organism.