Computer simulation of a mulluscan pigmentation pattern.

The formal characteristics of a colour pattern of complex appearance on a molluscan shell were studied by developing a computer program which produces an acceptable simulation of it. The pattern clearly involves a random factor determining points of initiation of diverging lines of pigment. The programme contained parameters controlling the density of random initiation points in different sectors of the growing edge of the shell, and the angle of divergence of the lines. In order to produce a satisfactory simulation, it was necessary to introduce another rule, by which new initiation points arising within a certain distance of an existing pigmentline are drawn on to that line. It is shown that the formal rules of the program can be given a plausible physiological interpretation.