ANIMAL CHEMISTRY, the department of organic chemistry which investigates the composition of the fluids and the solids of ani mals, and the chemical action that takes place in animal bodies. There are four elements, sometimes distinctively named organic elements, which are invariably found in living bodies, namely, carbon, hydrogen, oxygen and nitrogen. To these,may be added, as frequent constituents of the human body, sulphur, phosphorus, lime, sodium, potassium, chlorine, iron and iodine. The four organic elements are found in all the fluids and solids of the body. Sulphur occurs in blood and in many of the secretions. Phos phorus is also common, being found in nerves, in the teeth and in fluids. Chlorine occurs al most universally throughout the body; lime is found in bone, in the teeth and in the secre tions; iron occurs in the blood, in urine, and in bile; and sodium, like chlorine, is of almost universal occurrence. Potassium occurs in muscles, in nerves, and in the blood corpuscles. Minute quantities of copper, silicon, manganese, lead and lithium are also found in the human body. The compounds formed in the human organisms are divisible into the organic and inorganic. The most frequent of the latter is water, of which two-thirds (by weight) of the body are composed. The organic compounds may, like the foods from which they are formed, be divided into the nitrogenous and non-nitrogenous. Of the former the chief are
albumen (found in blood, lymph and chyle), casein (found in milk), myosin (in muscle), gelatin (obtained from bone), and others. The non-nitrogenous compounds are represented by organic acids, such as formic, acetic, buty ric, stearic, etc.; by animal starches, sugars; by fats and oils, as stearin and olein, and by alcohols (two compounds, cholesterin and glyc erin).
Bibliography.— Aberhalden, (Lehrbuch der physiologischen Chemie' (1906) ; Bunge, (Text Book of Physiological and Pathological Chem istry' (Leipzig 1894) Chittenden, (Physiolog ical Economy of Nutrition' (New York 1909) ; Cohnheim, (Chemie der Eiweisskiirper' (Leip zig 1904) ; Hammarsten, of Physi ological Chemistry' (New York 1904) ; Hoppe Leyler, (Handbuch der physiologisch- und pathologisch-chemischen Analyse ftir Aerzte und Studirende' (Berlin 1893) ; Lea, The Chemical Basis of the Animal Body' (in ap pendix to Foster's New York 1896) ; Mann, (Chemistry of the Proteids' (1906) ; Salkowski, (Practicum der physio logischen Chemie' (Berlin 1893) ; Schryver, (Chemistry of the Albumens' (1906) ; Waller and Lynes, (Elementary Physiological Chemis try' (1897) ; Wurtz, (Traite de chimie biolog ique' (Paris 1885).