German biologist Hilde Mangold studied the process by which part of an embryo--sometimes called an organizer--causes other parts of the embryo to form specific types of tissues and organs. This process is called embryonic induction. Working under the direction of German biologist Hans Spemann (1869-1941), Mangold helped discover the location of the organizer in amphibians.

Mangold had attended the University of Frankfurt, where she had once been to a lecture by Hans Spemann. Spemann was studying the processes that control the development of amphibian embryos, and Mangold was intrigued by his experiments. After she graduated, she moved to Freiburg, Germany, where Spemann was head of the Zoological Institute. Mangold began working on an advanced degree, and Spemann suggested a series of experiments for her doctoral thesis.

Spemann proposed that Mangold should work with early embryos of two species of newts. Her experiments would involve transplanting a portion of...