METHODS

1. Vitamin A was determined in small quantities of serum by the spectrophotometric method of Bessey, Lowry, Brock, and Lopez (5) utilizing the principle of destruction by exposureto ultraviolet light of the vitamin A present in a xylene-kerosene extract of serum. All samples were analyzed in triplicate for both carotene and vitamin A, in a Beckman model DU spectrophotom-eter, at wave lengths of 460 millimicrons for carotene and 328 millimicrons for vitamin A. 2. The test material consisted of clear solutions of synthetic vitaminA palmitate in corn oil, containing ap-proximately 10,000 micrograms vitamin A per ml. This was a very stable product, showing little or no deterioration in assayable vitamin A when kept in amber bottles in the refrigerator. A single dose of 10.5 ml. of this oil was administered by mouth or through rubbertubes as de-scribed below.