The Association of Vitamin A with the Lipochromes of Plant Tissues

Abstract

DURING the investigation of the conditions of formation of vitamin A in seedlings reported in the preceding paper, the association of vitamin A with lipochromes in plant tissues already emphasised by Steenbock and his co- workers (subsequent references) was being kept in view. Much of the earlier work on vitamin A consisted of the examination of such plant tissues as were commonly in use as' food for human beings and farm stock. Steenbock and Gross [1919] found that, of all the roots and underground stems examined by them, the carrot and sweet potato were the only two that contained this -vitamin; the other seven they described as a "complete failure." These latter included rutabaga, dasheen, red beet, parsnip, potato, mangold and sugar beet. In each experiment the root formed 15 % of the diet of the test animals, andin the case of the carrot and sweet potato, gave good growth. The minimum dose for growth of each of these was not determined, so that no exact comt parison between the two was ever drawn. A rather more quantitative examina-