ABSTRACT
In recent years, pattern formation in chaotic systems has become a great theme among mathematicians and their computers. We have already come across examples in crystal structures growing within the vesicular cavities of oyster shells (Pl. 2.5). Some of them resemble snowflakes, the regular shapes of which Johannes KePler (1571-1630), better known as an astronomer, mused over. Only recently have they become understood as kinds of dissipative systems, in which the crystal lattice and the rules of fractal growth result in extremely regular, yet unpredictable, details.
