This was Hilde Mangold's thesis. Spemann designed the experiment, and Mangold performed the work, and was the co-discoverer of the "organizer," the chemical that directs the embryonic development of tissues and organs. Spemann added his name to Mangold's paper over her objections. Spemann was awarded the Nobel Prize in 1935 for discovery of the “organizer” in animal development. Because Mangold died at the early age of 26 when the gas heater in her apartment exploded, she was unable to share the Nobel Prize with Spemann. Digital facsimile of the English translation by Viktor Hamburger is available at www.ijdb.ehu.es/web/descarga/paper/11291841. See also Spemann's Experimentelle Beiträge zu einer Theorie der Entwicklung. Deutsche Ausgabe der Silliman Lectures gehalten an der Yale University im Spätjahr 1933 (Berlin: Julius Springer, 1936). Translated into English as Embryonic development and induction (New Haven: Yale University Press, 1938). See Hamburger, The heritage of experimental embryology: Hans Spemann and the organizer. New York: Oxford University Press, 1988.