This publication presents the results of a study of physical and physiological differences that exist between kernels of open-pollinated field corn harvested at different stages of development. Differences in physical characteristics of the kernels and in the rapidity of germination and of breakdown were found to be caused by physiological differences which, in turn, resulted largely from the stage of development at which the kernels were harvested. Studies of the effect of slow as compared with rapid drying, and of the value of selecting seed from plants grown on soil to which superphosphate was added are also reported. It is hoped that the results presented herein will help answer some of the questions pertaining to the effect of the time of gathering and methods of handling of seed corn upon its value as seed.