Phosvitin in the Serum of the Hen

A PHOSPHOPROTEIN fraction appears in the serum of the hen in association with the onset of laying 1,2 or in the serum of the immature bird on treatment with œstrogen 3 . It can be shown by zone electrophoresis on filter paper that two new major protein fractions appear in the serum on œstrogenization, one of these being specially rich in protein phosphorus 4 . The demonstration by Mecham and Olcott 5 of the existence of phosvitin in egg-yolk, and the view that yolk constituents are synthesized in the liver and transferred thence to the ovary in the blood plasma, prompted us to examine the blood of the hen for presence of phosvitin.