German embryologist who was awarded the Nobel Prize for Physiology or Medicine in 1935 for his discovery of the effect now known as embryonic induction, (induction) the influence exercised by various parts of the embryo that directs the development of groups of cells into particular tissues and organs.

Spemann, initially a medical student, attended the universities of Heidelberg, Munich, and Würzburg and graduated in zoology, botany, and physics. He worked at the Zoological Institute of Würzburg (1894–1908), held a professorship at Rostock (1908–14), was director of the Kaiser Wilhelm Institute for Biology in Berlin (1914–19), and occupied the chair of zoology at Freiburg (1919–35).

Spemann's concept of induction was based upon a lifetime of research into the early development of the newt. His work showed that, in the earliest stages, the fate of the embryonic parts has not been determined: if a piece of presumptive skin tissue is excised and transplanted into an area of presumptive nervous tissue, it will form nervous tissue, not skin. These results illuminated not only normal processes of development but also the origin of congenital abnormalities. Spemann summarized his researches in Experimentelle Beiträge zu einer Theorie der Entwicklung (1936; Embryonic Development and Induction).