 Driesch’s experiments (see  Section 7)  demonstrated regulative development: the developing embryo compensated for experimental intervention rather than following a pre-determined plan. To account for this phenomenon without resorting to vitalism, a new theoretical approach was needed. One such was organicism, which Donna Haraway (1976) casts as a new Kuhnian paradigm for embryology in the first half of the twentieth century. Its tenets included: