ABSTRACT
Because he found copper, manganese, and zinc to be widely distributed in tissues of plants and animals, McHargue (1) attempted to assess the role played by these elements in the nutrition of animals. Rats were maintained in glass cages and fed a semipurified diet containing ingredients selected for low mineral content. It was concluded that “manganese definitely and possibly copper and zinc have important biological functions in animal metabolism.” Subsequent research at Wisconsin by Kemmerer et al. (2) and by Orent and McCollum (3) at Johns Hopkins confirmed these observations. The recognition of the need for vitamin supplementation by these latter investigators provided stronger evidence than that provided by McHargue.
