FAT TISSUE, or ADIPOSE TISSUE, the deposits of fat in various parts of the animal organism. Fat tissue consists of a specific form of cells which occur usually in groups. When fully developed the distended cell walls filled with fat are connected by a special delicate form of connective tissue, in which is a network of blood-capillaries en closing each cell. In the living tissue the fat is liquid, but after death it congeals to a solid or semi-solid condition. The fats found in animal fatty tissue are mainly the triglycerides of stearic acid, palmitic acid and oleic acid. In the fat of man oleic acid is the largest con stituent, making up 65 to per cent of the fatty deposit. The proportion of palmitic acid ranges from 8 to 25 per cent; and of stearic acid, from 2 to 6 per cent, according to the part of the body from which the fat is derived. Other components of fat tissue are smallr centages of lecithin, cholesterin and free acids and of a yellow lipochrome which gives its hue to the fat. Fat is found in the young of
vertebrate mammals from the moment of their birth, and under normal conditions continues to increase till puberty, when a marked diminu tion usually takes place. In middle life fat commonly increases and sometimes is acquired to gross excess. The origin of fat in the tissues has not been accounted for. It has been proved that while some of it is transferred from the fat eaten as food, other deposits seem to be due to a transformation of albuminous substance which is not understood. The function of fat in the body is not known, but it has been ob served that fat in a proper quantity acts as a protective shield against atmospheric changes; serves as a lubricant to several organs and, above all, stores up the heat energy so essential to animal vitality.