In order to facilitate comparison with previous work,1 the children chosen for this study were between 7 and 17 years of age. Fifty of each sex were chosen. All of the boys and forty-two of the girls were patients in Gillette Hospital; the remaining eight girls were patients in Shriners' Hospital.
The blood was drawn by venipuncture about two hours after breakfast. The sedimentation rate was determined by the Cutler graphic method,2 0.5 cc. of oxalate instead of citrate being used. Readings were taken at intervals of fifteen, thirty, forty-five and sixty minutes. The fibrin was determined in duplicate by the Wu3 colorimetric method, the precautions mentioned in earlier papers being observed.
The average sedimentation index (one hour reading) was 12.58 ± 0.83 mm. for the boys and 12.64 ± 0.67 mm. for the girls. The difference between the sexes is 0.06 ± 1.06 mm., which is