The tendency for drawings of men and animals when used as decorative designs to degenerate, in the course of time and repetition, into more and more simple lines, to become more and more "grammatized" and simplified, till at last their origin is hardly recognizable, is both a very remarkable and a very usual thing. The process of degeneration, step by step, can often be traced, and curious remnants of important parts of the original drawing are found surviving in the final simplified design. The paddles and other carvings of some of the South Sea Islanders show very curious "degenerations" of this kind. A carved human head with open mouth becomes by repeated copying and simplification a mere crescent or hook, which is the vastly enlarged mouth of the original face. It alone survives, and is of enormous size, when all other features and detail have been abandoned. In some carvings of a face the tongue is shown projecting as an indication of defiance. In course of simplification in successive reproductions the face becomes a mere curved surface with a large pointed piece standing out from it; it is the tongue. That one significant thing–suggesting defiance–alone persists. The study of this process in human art covers a very wide field, including all races and all times. An excellent example is that given in Fig. 51. It shows the step by step "grammatizing" of a favourite decorative drawing–that of an alligator, as painted by the Chiriqui Indians of Panama on pottery. We start in Fig. 51, A, with an alligator, already considerably "schematized" or conventionalized. The Indians could do better than that, but it served for pottery decoration. The figures B, C, D show three stages of further "grammatizing" of the design (from different parts of the surface of a pot) till, in D, we get the alligator reduced to a yoke-like line and a dot! [Illustration: FIG. 51.–Four stages in the simplification of a decorative design–the Alligator–as painted on pottery by the Chiriqui Indians. (Holmes.)]