AbstractsChemistry

Knowledge o£ the importance or a nutritional factor in the etiology of rickets may be said to date from the pioneer work of Mellanby in 1919. The therapeutic value of fish oils tor rickets. although recognized for centuries~ was shown to be due to a factor quite distinct from vitamin A. The exact identity of the factor. however~ was obscured for some time when it was found that sunlight and ultraviolet irradiation also had curative effects. In 1926 accidental discovery of the role of cholesterol and related sterols made it possible to conclude that sunlight and cod liver oil cure rickets because sunlight produces in the skin the sarne (or a similar) vitamin which cod liver oil provides ready made.