The development of blood plasma.—Part I. The genesis of coagulable material in embryo chicks

Abstract

Although much attention has been given to the embryonic development of blood corpuscles, the genesis of the coagulable constituents of the plasma has escaped notice. Knowledge of this subject appears to be limited to the observation of Boll (1) that the blood of chick embryos does not clot before the twelfth to fourteenth day of incubation; and of Emmel, Levison and Fisch (2) that the blood of late pig embryos clots more slowly than that of adult pigs. We shall describe the successive appearance in chick embryos of those constituents of the blood plasma which are associated respectively with the preservation of the fluidity of the blood and with its capacity to clot. We shall also briefly discuss the significance of the facts recorded.