This article highlights the contradiction between theories of form in musicology (originating in the mechanistic and organicist definitions of the eighteenth and nineteenth centuries), and new forms created by contemporary composers since circa 1970. The initial discussion introduces various “traditional” definitions of form in aesthetics, semiotics and musicology. Following this, a critique of the mechanistic approach, drawing on the work of André Souris, is presented. The third part discusses some recent scientific theories which composers have drawn from. The remainder of the article provides examples of the manifestation of new musical forms based on scientific theories such as the spiral, morphogenesis, fractal geometry, psychological-literary analysis, and L-systems.