Concerning the process of biological synthesis of riboflavin, the author picked up barbituric acid, alloxan, uric acid, o-xylidine, dimethylbenzimidazole and dimethylphenvlendiamine as presumable intermediates, and the effect of these substances on riboflavin synthesis was tested following a method which was divised by the author. But it was not able to obtain the positive results on these substances.
