 An important spur to gradient and field theories was the phenomenon of “the organizer”, demonstrated by Hilde Mangold’s experiments transplanting newt tissue. She moved a small piece from the dorsal lip of a developing Triton cristatus embryo into the early gastrula of another newt species (Triton taeniatus). Donor tissue thus came in contact with undifferentiated ectoderm of another species. The result: two conjoined embryos with different body axes. This indicated that dorsal lip tissue somehow “organized” host cells and tissues into another embryonic body. Spemann designated the dorsal lip of the embryo “the organization-center” or “organizer”. But how did this work? The proposed answer suggested that body axes result from a gradient of some chemical substance emanating from cells of the organizer. This was the starting-point for “field theories”; e.g.,