Correlation between physical retardance of photographic gelatine and its absorbance at 260mμ as a measure of RNA content is studied with many photographic gelatines. Apparently there exists no correlation between these properties, never-the-less physical retardance of an inert gelatine increases linerarly with the amount of RNA addition to some extent. Possible causes of the controversy between these facts are examined. A method of correction of the contribution of tyrosine absorption is tried with a result of a little improved correlation. Addition of adenine or thymine increases absorption at 260 mμ but does not affect physical retardance. With IAG gelatines which contain no artificial addition, the correlation becomes more apprent. As there are several gelatines that have similar absorbance at 260mμ but differ much in physical retardance, there must be another factor that affects physical retardance.