It will be necessary, in the first place, to examine briefly the normal tendencies of color combination while still under the direct domination of constructive elaboration. In the way of illustration, let us take first a series of filaments, say in the natural color of the material, and pass through them in the simplest interlaced style a second series having a distinct color. A very simple geometric pattern is produced, as shown in Fig. 315. It is a sort of checker, an emphasized presentation of the relievo pattern shown in Fig. 291, the figures running horizontally, vertically, and diagonally. Had these filaments been accidentally associated in construction, the results might have been the same, but it is unnecessary to indicate in detail the possibilities of adventitious color combinations. So far as they exhibit system at all it is identical with the relievo elaboration. [Illustration: FIG. 315. Pattern produced by interlacing strands of different colors.] [Illustration: FIG. 316. Pattern produced by modifying the alternation of fillets.] [Illustration: FIG. 317. Isolated figures produced by modifying the order of intersection.] Assuming that the idea of developing these figures into something more elaborate and striking is already conceived, let us study the processes and tendencies of growth. A very slight degree of ingenuity will enable the workman to vary the relation of the parts, producing a succession of results such, perhaps, as indicated in Fig. 316. In this example we have rows of isolated squares in white which may be turned hither and thither at pleasure, within certain angles, but they result in nothing more than monotonous successions of squares. [Illustration: FIG. 318. Pattern produced by simple alternations of light and dark fillets. Basketry of the Indians of British Guiana.] Additional facility of expression is obtained by employing dark strands in the vertical series also, and large, isolated areas of solid color may be produced by changing the order of intersection, certain of the fillets being carried over two or more of the opposing series and in contiguous spaces at one step, as seen in Fig. 317. With these elementary resources the weaver has very considerable powers of expression, as will be seen in Fig. 318, which is taken from a basket made by South American Indians, and in Fig. 341, where human figures are delineated. The patterns in such cases are all rigidly geometric and exhibit stepped outlines of a pronounced kind. With impacting and increased refinement of fillets the stepped character is in a considerable measure lost sight of and realistic, graphic representation is to a greater extent within the workman's reach. It is probable, however, that the idea of weaving complex ideographic characters would not occur to the primitive mind at a very early date, and a long period of progress would elapse before delineative subjects would be attempted.