SKELETON

(Yunanca köken — orijinale bakınız.) The desicca ted support or framework of an animal body, which, usually consisting of different parts, may be joined together by the dried natural ligaments, when it is termed " a natural skeleton;"or may be articulated artificially, when it is termed "an artificial skeleton." In the lowest-oreanized animals, as the Poly gas tri a and Polypi, the skeleton, when it exists, commonly consists of a single piece. In the Poly gas tri a it is external, in the form of a case, and consists of pure silex. In the Polypi it is sometimes external, sometimes internal; and is composed of either pure carbonate of lime, or with a small additional proportion of phosphate of lime, and these earths are combined with a greater or le proportion of ge latino us animal matter. In tho lsis the skeleton consists of numerous separate calcareous joints, connected together by portions of uncalcified gelatin. In many of the Litho phytous Polypes innumerable minute spicula;, of various but definite forms, are scattered through the fleshy investment of the main internal skeleton. In the Echinoderms the skeleton is external, as regards the viscera, but is covered by an organized skin. It is chiefly remarkable for the great number of pieces of which it is composed, and the regular and beautiful forms In which they are combined; it likewise supports numerous tubercles or spines: it is composed of carbonate and phosphate of lime, with a gelatinous basis. in Insects the skeleton is partly internal, but chiefly exter nal; and Its hardening material is a peculiar animal princl pie, called " chitine." In cabinets of dried insects it is the natural skeleton that is preserved. In Crustacea the skele ton, which bears the same relative position to the animal as in insects, is rendered denser and more brittle by being consolidated with the carbonate and phosphate of lime. In the Mollusca the skeleton is generally external, but some times internal: it is hardened by the carbonate 1139of lime, with [s. 1143]