Hans Spemann (; 27 June 1869 – 9 September 1941) was a German embryologist who was awarded a Nobel Prize in Physiology or Medicine in 1935 for his student Hilde Mangold's discovery of the effect now known as embryonic induction, an influence, exercised by various parts of the embryo, that directs the development of groups of cells into particular tissues and organs. Spemann added his name as an author to Hilde Mangold's dissertation (although she objected) and won a Nobel Prize for her work. Biography Hans Spemann was born in Stuttgart, the eldest son of publisher Wilhelm Spemann and his wife Lisinka, née Hoffman. After he left school in 1888 he spent a year in his father's business, then, in 1889–1890, he did military service in the Kassel Hussars followed by a short time as a bookseller in Hamburg. In 1891 he entered the University of Heidelberg where he studied medicine, taking his preliminary examination in 1893. There he met the biologist and psychologist Gustav Wolff who had begun experiments on the embryological developments of newts and shown that, if the lens of a developing newt's eye is removed, it regenerates. In 1892 Spemann married Klara Binder with whom he had a daughter (Margaret) and three sons (Fritz, Rudolph, Ulrich). In 1893–1894 he moved to the University of Munich for clinical training but decided, rather than becoming a clinician, to move to the Zoological Institute at the University of Würzburg, where he remained as a lecturer until 1908. His degree in zoology, botany, and physics, awarded in 1895, followed study under Theodor Boveri, Julius von Sachs and Wilhelm Röntgen. For his Ph.D. thesis under Boveri, Spemann studied cell lineage in the parasitic worm Strongylus paradoxus, for his teaching diploma, the development of the middle ear in the frog. Spemann advocated a holistic approach to biology. Experiments in ontogeny During the winter of 1896, while quarantined in a sanitarium recovering from tuberculosis, Spemann read August Weismann's book The Germ Plasm: A Theory of Heredity. He wrote in his autobiography: "I found here a theory of heredity and development elaborated with uncommon perspicacity to its ultimate consequences.....This stimulated experimental work of my own". Results in embryology had been contradictory: in 1888 Wilhelm Roux, who had introduced the experimental manipulation of the embryo to discover the rules of development, performed a series of experiments in which he inserted a hot needle into one