Cxxiv. the Alkaline Hydrolysis of Lecitho-vitellin with Particular

MIESCHER [1870] observed that after prolonged peptic digestion of egg-yolk an insoluble substance separated out. This substance was foundby Bunge [1885] to contain iron in organic combination and was named by him " haematogen" because of its close resemblance to haemoglobin, at least so far as empirical composition was concerned. The chemical nature of this substance was investigated in more detail by Hugounenq and Morel [1905, 1, 2; 1906]. Again, Posternak [1927] has studied a similar iron-containing enzyme-resisting substance. The inconsistent results obtained for the iron content of this material indicate that haematogen is not a pure compound. Haematogen was regarded by these workers as a prosthetic group in the vitellin molecule and as being a precursor of the haemoglobin formed during avian embryonic development. A more detailed discussion of their findings is given by McFarlane, Fulmer and Jukes [1930] and by Jukes and Kay [1932]. Levene and Alsberg [1900] have obtained from vitellin an iron-containing substance, vitellinic acid, by the action of strong ammonium hydroxide. It is probable that vitellinic acid is a purer substance than haematogen since these workers avoided enzymic hydrolysis and employed the protein, vitellin, instead of egg-yolk. All these investigations were, however, carried out without knowledge of the presence of a second protein in egg-yolk. Livetin, this second protein [Plimmer, 1908], was first prepared by Kay and Marshall [1928] in pure form. The constitution of the egg-yolk-protein has long been considered to resemble that of the milk-proteins. Rimington and Kay [1926] found that very mild hydrolysis of caseinogen with 1 % sodium hydroxide liberates the organic phosphorus from the protein molecule as inorganic phosphorus. We were therefore interested in determining what action dilute sodium hydroxide would have on lecitho-vitellin. In the course of this investigation we obtained results which indicated that the lecitho-vitellin molecule contained copper as well as