The system of the acanthus leaf is based entirely on radiation, the tines and veinings being arranged in consistently diverging directions from a common base or start-point. Whether the whole leaf be displayed or merely the half leaf used, the shape should be bounded by general lines controlling the lobes and their serrations--the mass shape forming a satisfactory silhouette. The length of the lobes should be relative to the breadth of the leaf, the maximum length agreeing with the maximum width, and the others in proportion. The edges or outlines of serrations and lobes should also be controlled by radial lines from the base. [Illustration: No. 253. Construction of the Acanthus Leaf.] In turn-overs and curling or twisting lobes the silhouette shape and composing line must be considered. The apex of leaf terminates with a central lobe balanced by side lobes repeated throughout. In treatment these may be displayed clear of each other, or they may overlap, but care must be taken to avoid confusion in effect. CHAPTER VII TREATMENT IN DESIGN Appreciation of design by the individual is largely a matter of temperament, though it may be due to some extent to acquired knowledge. Generally, few are conscious of any guiding principle, and selection in their case is mostly the result of fashion or custom. To others certain colours and forms have an appeal, though they may be quite unconscious of, or unable to explain the attraction other than it suits their taste. In the last few years it has been recognised that colour may be employed beneficially in curative treatment, but the normal healthy individual is often indifferent to environment other than that of material gratification. When any artistic work creates pleasurable emotion, it is purely a matter of cause and effect. To design successfully involves some understanding of the causes or factors which constitute the appeal. _Natural Attraction_ The attraction of colour and form is undoubtedly universal, and may be generally understood, though there are delicate degrees of proportion and association in both that may only be appreciated by the cultivated eye. Early essays in drawing generally exhibit an undesirable redundancy in curves, and in many instances the student is slow to realise that those that approximate to the elliptic form are proportionately of more interest than those obviously composed of segments of circles. Undoubtedly this subtlety of line is one of the predominant factors in appreciation of form. A factor in pattern that is largely responsible for the charm is the presence of small detail in juxtaposition with larger forms. This is entailed in instances by technical conditions, such, for instance, as in some tapestries where inhabited pattern is essential to the process of production. _Decorative Materials_