The Blood-Plasma holds in solution two albuminous substances, namely, serum albumen and fibrinoplastin or serum globulin, besides a variety of nitrogenous substances in small quantity, most of which are in process of excretion, such as urea, uric acid, kreatin, etc. There are besides, as constant constituents, fats, sugar, and various salts, of which the chief are sodium chloride and phosphate.