Larry Poons (b. 1937) shot to fame while still in his twenties, on the strength of his "dot paintings," in which dots or ellipses were meticulously arranged on brightly colored fields, creating a rhythmic, pulsating effect. But within a few years, Poons first loosened the hard-edged precision of the dot paintings and then abandoned them entirely for an organic mode of abstraction based on vertical drips of flung paint. This marked the beginning...