Tomatoes are a good source of both provitamin A (X-carotene) and vitamin C, and they are of greater value in human nutrition as a source of essential vitamins and minerals than as a source of energy. Studies here reported were made to determine the genetic variability in the contents of provitamin A and vitamin C of commercial varieties and related forms and species of Lycopersicon. According to MULLER (3), the genus Lycopersicon includes six species, five of which have been introduced into the United States by the Division of Plant Exploration and Introduction, U.S. Department of Agriculture. The species are widely divergent in fruit, vegetative, and growth characteristics, and it is reasonable to expect that considerable differences may exist also in their contents of provitamin A and vitamin C. The experiments were conducted at Lafayette during the summer of I942. At least five plants of each strain were grown, and usually a sample of fruit was collected for analysis from a single plant that appeared typical of that strain. Samples of fruit for analysis were collected from August i8 to September 28. A control variety, Baltimore (Indiana strain), was planted every fifth row and was analyzed at intervals throughout he season. This variety served as a control on variation in vitamin content arising from environmental differences in the plot and due to different dates of sampling. Carotenoid pigments were extracted with an acetone-hexane mixture. Carotenols (5) were removed by successive ex-