Saburo Maraoka: Studies on the Antimetabolites of Amino Acids, ‡] ‡U Effects of Argininosuccinic Acid and Canavaninosuccinic Acid on the Growth of Lactobacillus arabinosus 17-5. (Faculty of Pharmacy, Kyoto University*3) Lactobacillus arabinosus, strain 17-5, requires arginine or pyridoxal in the Henderson Snell medium. This lactobacillus grows in a pyridoxal-free medium by the addition of ornithine or citrulline in place of arginine and, therefore, arginine acitivity of arginino succinic acid was examined under this medium condition.