The contractility of 64 rat scroti were measured by submerging anesthetized rats in a water bath and recording the scrotal movements which accompanied temp. change on a kymograph drum. Significant decreases in height of contraction occurred during the 1st 4 wks. following castration. Scrotal sac weight decreased significantly during the 1st 2 wks. after gonadectomy and a coefficient of correlation of .915 between height of contraction and scrotal sac wt. was demonstrated. Coefficients of correlation of .801 and .843 were demonstrated between contraction height and seminal vesicle wts. and between scrotal sac and seminal vesicle wts. respectively.