Hans Spemann (German: [ˈhans ˈʃpeːˌman] ; 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, one of the first steps towards cloning. 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, from 1889 to 1890, he did military service in the Kassel Hussars followed by a short time as a bookseller in Hamburg. In 1891, he entered Heidelberg University 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). From 1893 to 1894, he moved to the Ludwig-Maximilians-Universität München 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. He was a protestant. 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 of two blastomeres to kill it. He then observed how the remaining blastomere developed, and found that it became a half embryo. In 1892, Hans Driesch performed similar experiments on sea urchin embryos, but instead of killing one of the two blastomeres he put many embryos in a tube and shook it to separate the cells. He reported that, contrary to Roux's findings, he ended up with completely formed but smaller embryos. The reason for this discrepancy has been widely attributed to Driesch separating the two blastomeres completely rather than just killing one as Roux had done. Others, including Thomas Hunt Morgan and Oscar Hertwig, attempted to separate the two cells, for the matter was of great importance, particularly to the arguments between proponents of epigenesis and preformation, but satisfactory results could not be achieved. As a master of micro-surgical technique, beginning with his continuing work on the amphibian eye, Spemann's papers in the early years of the 20th century on this vexed question were to be a great contribution to the development of experimental morphogenesis, causing him to be hailed in some quarters as the true founder of microsurgery. He succeeded in dividing the cells with a noose of baby hair. Spemann found that one half could indeed form a whole embryo, but observed that the plane of division was crucial. This dispatched the theory of preformation and gave some support to the concept of a morphogenetic field, a concept of which Spemann learned from Paul Alfred Weiss.
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