FETTEINE AND TIIE PROTEINE BODIES, Under the term proteine bodies, chemists include the following substances: Albumen. fibrine, syntonine or muscle-filaine, caseine, globulins, and laemato-crystalline. Albumen, fihriue, and caseine are common both to the animal and vegetable kingdom; while the three others occur only in the animal king. door (namely, 'in muscular tissue, in the crystalline lens of the eye, and in the blood cells). The most careful analyses have shown that in their composition, these substances arc almost identical, and that they all contain about 53.6 per cent of carbon, 7.1 of hydrogen, 15.6 of nitrogen, and 22.1 of oxygen, with a varying quantity of sulphur not exceeding 1.6 per cent. These substances are as similar in many of their properties, and in the products of their decomposition, as in their ultimate composition, and hence chemists were naturally led to entertain the view that they possessed a common radical. Mulder (q.v.) announced. in 1838, that he had discovered this radical, which, from its importance, he named RIZOTEINE (Gr. proteup, I hold the first place), and that he had found that albumen, fibrine, caseine, etc. (which at that period were known as the albuminous bodies, the albaminoid group, or the albuminates), were combinations of this proteine with sulphur and phosphorus, or simply with sulphur. The composition of this proteiue is represented. according to the discoverer, by the formula Liebig and several of his pupils have, however, shown that 3lulder'sproteine always con tains a small but variable amount of sulphur; and they deny, on what are generally deemed sufficient grounds, the existence of proteine as a separate body. The term pro teine bodies, or proteine compaulid3, is, however, commonly retained both by physiologists and chemists, as being the most convenient one for representing a class of compounds, which, whether Mulder's theory is correct or not, deserve their name front their con stituting the group which form the most essential articles of food.
The PROTEINE BODIES may be generally described as nearly colorless, neutral, nitrog enous bodies, soluble in potash solution, and not yielding gelatine when boiled with water. They all present two modifications, differing essentially from one another; in one of which they are soluble, and in the other nearly or quite insoluble. They exist naturally only in the soluble modification, although not necessarily in a state of solution. Most of them are transformed into the insoluble state by boiling, by the mineral acids, and by numerous salts; and one of them, fibrine, undergoes this modification on simple removal of the blood, or other fluid containing it, from the organism. This passage from the soluble into the insoluble form, is temed coagulation, but we do not know what chemical change takes place in the process.
The soluble proteine bodies, in their dried state, form pale yellow, translucent masses, devoid of smell and taste, which are soluble in water, but insoluble in alcohol and ether. They ate precipitated from their watery solutions by alcohol, by the mineral :wit's, by tannic acid, but not by the vegetable generally; and by tunny mineral oxides and salts. The insoluble proteine bodies, when freshly precipitated. are of a white color, in flakes or small clots, or viscid and glue-like; when dried, they may be reduced to a whitish powder.
The products of the decomposition of the proteine bodies are very numerous, and the study of those products is of great importance. as tending to elucidate the changes which the tissues undergo in the body during their disintegration.
PROTEL'IDiE. See