 She examines these elements in the work of the paradigm’s principal architects in twentieth-century developmental biology: Ross Harrison, Joseph Needham, and Paul Weiss. Organicists sought mathematical yet autonomously biological laws to account for emergent order in developmental processes. Although such laws did not materialize, Haraway argues that metaphors (principally those of crystals and fields) played significant theoretical roles in their stead. More abstract theoretical concepts—of polarity, gradients, and fields—were also used to explain organismal form in the first half of the twentieth century. For example, Hans Spemann (1936 [1938]) proposed that