The Phosphorus of Caseinogen

the isolation from caseinogen of a pure phosphorus-containing peptone has been described. This substance, which has been named phosphopeptone, and whose composition is represented by the formula C37H62033N9P3, has been isolated in a yield corresponding to 50 % of the organic phosphorus of the original tryptic digest. In the present paper evidence is adduced to show that the remaining organic phosphorus is present in similar if not identical form, and an account is given of the isolation and identification of the individual units of phosphopeptone, together with a suggested structure.