Abstract
The following results were obtained by observations on the content of riboflavin and other fluorescent substances of feces in men loaded with riboflavin. (1) When an excessive amount of riboflavin was loaded to men once a day for 5 days, the riboflavin content of feces increased remarkably on the 1st day, but it underwent no further changes. (2) A violet fluorescent substance having Rf 0.41 appeared always in human feces. It is likely that this violet fluorescent substance is an intermediate substance of riboflavin formation.
