Think of 20 straight rays emanating from the center of the curves (which is the center of the only circular curve contained in the sequence of 15 closed curves).
Those rays are spread around the center in constant angular distance (of 18 degrees). On each of these rays, a point is chosen at random. However, the choice is not quite so random. Indeed, the first curve, i.e. the perfect circle, is determined by its radius only. From there to the outside, a point is chosen beyond the circle up to some maximum value. The first three of these new points determine a polynom of degree 2 (a parabolic arc). This arc defines the first piece of the new curve. The process is repeated around until the last arc returns to the start.

This procedure is repeated four times to the outside, and then nine times to the inside of the circle.

This description of the old scheme of 1965 contains a lot to be further parameterized. Generative art is always about parameters.