On this day, 84 years ago, on September 12, 1941 (July 21, 1941 in the lunar calendar), the famous German embryologist Hans Spemann was persecuted to death by Hitler. On September 12, 1941, Hans Spemann, a famous German zoologist and embryologist, was persecuted to death by Hitler for not succumbing to fascism. Hans Spemann was born in Germany in 1869. After graduating from high school, he joined the army. After retiring, he helped in the family business. Later, he changed his ambition to study medicine. After graduation, he worked in the Department of Zoology at the University of Würzburg. He has served as a professor at the University of Rostock and the University of Freiburg, and won the 1935 Nobel Prize in Physiology and Medicine for discovering the "organizational center" in the embryo of salamander. The main achievement was his discovery of the fact that each cell nucleus in the early stage of the embryo was very similar in terms of growth and development functions. Later, he used experiments to prove that the back lip of the amphibian gastrula can promote its adjacent ectodermal cells to differentiate into nerve tissue., jointly forming a central structure composed of notochord, muscles, and nerve capsule. This scientific conclusion enabled embryology to develop in the right direction. He was the first to conduct an artificial monozygotic twin experiment.