Came to replace descriptive embryology in the middle of the 19th century as means of trying to identify experimentally the ‘mechanics’ of growth and development (the causal-analytic approach). Experimental manipulations included the selective destruction of tissues (Wilhelm Roux, 1850-1924; Hans Driesch, 1867-1941) or the transplantation of one body part to another part of the body (Hans Spemann, 1869-1941). The latter manipulation was aimed at finding the organiser or organising center that induced the formation of the neural tube. In general terms, an organiser is a part of the embryo that provides a stimulus for the direction of morphogenesis and the differentiation of other parts.
See Developmental biology, Differentiation (embryology), Embryology, Induction (embryology), Equipotentiality, Morphogenesis, Neural tube, Organizer (embryology)