ABSTRACT In birds albumen represents a substantial part of the reserve material for their embryological development (Romanoff & Romanoff, 1949). In Gallus gallus albumen proteins form 50 % of non-incubated egg protein content (Romanoff & Romanoff, 1949). During incubation such material is absorbed and utilized, to a great extent, for the synthesis of embryonal proteins (Fiske & Boyden, 1926; Rupe & Farmer, 1955). It is not yet well understood how these processes (albumen absorption and utilization for the energetic and nutritional needs of the embryo) take place. The present available data indicate that the amount of albumen solids begins to diminish starting from 11 to 12 days of incubation (Romanoff & Romanoff, 1933; Rupe & Farmer, 1955). From 13 to 14 days, after the sero-amniotic connexion perforates, the protein content of the amniotic fluid shows a marked increase because of the passage of albumen (Needham, 1931 ; Romanoff, 1960). During the same development period albumen proteins can be recovered, in large amounts, in the yolk (Saito, Martin & Cook, 1965; Carinci, Wegelin & Manzoli-Guidotti, 1966).