In experiments of Kluver on monkeys and of Hertz on bees, observed reactions indicate the presence of a neural mechanism which serves to order geometric figures in a linear sequence, so that any given figure occupies a definite place in a one-dimensional array. In a theoretical mechanism described by Rashevsky, presentation of a visual stimulus-figure results in an excitation at a given center whose intensity is a function upon the curve is examined in some special cases, and the mode of variation is further described qualitatively.