Background

Hans Spemann was born on June 27, 1869, in Stuttgart, Baden-Wurttemberg, Germany. He was the eldest of four children of a well-known book publisher Johann Wilhelm Spemann and the former Lisinka Hoffman. The family, which was socially and culturally active, lived in a large home that was well stocked with books, which helped shape the young Spemann’s intellect.

Education

Upon entering the Eberhard Ludwig Gymnasium, Spemann first wished to study the classics. Although he later turned to embryology—the branch of biology that focuses on embryos and their development—he never relinquished his love of artistic endeavors.

Before entering the University of Heidelberg in 1891 to study medicine, Spemann left Heidelberg in the mid-1890s to continue his studies at the University of Munich; he then transferred to the University of Wurzberg’s Zoological Institute to study under the well-known embryologist Theodor Boveri. Spemann quickly became Boveri’s prize student and completed his doctorate in botany, zoology and physics in 1895.

Career

Early in his career, Spemann worked at his father’s business and served a tour of duty in the Kassel hussars. His strict interest in medicine lasted only until he met German biologist and psychologist Gustav Wolff at the University of Heidelberg. Only a few years older than Spemann, Wolff had begun experiments on the embryological developments of newts and had shown how, if the lens of an embryological newt’s eye is removed, it regenerates. Spemann remained interested and intrigued by both Wolff’s finding and also in the newt, on which he based much of his future work. But more than the regeneration phenomenon, Spemann was interested in how the eye develops from the start. He devoted his scientific career to the study of how embryological cells become specialized and differentiated in the process of forming a complete organism.

In 1908 Spemann accepted a post as professor at the University of Rostock. During World War I, he served as director of the Kaiser Wilhelm Institute of Biology (now the Max Planck Institute) in Berlin-Dahlem, and following the war, in 1919, he took a professorship at the University of Freiburg.

By the time Spemann began research at the Zoological Institute in Wurzburg, he had already developed a keen facility and reputation for conducting well-designed experiments that centered on highly focused questions. His early research followed Wolff’s closely. The eye of a newt is formed when an out-growth of the brain, called the optic cup, reaches the surface layer of embryonic tissue (the ectoderm). The cells of the ectoderm then form into an eye. In removing the tissue over where the eye would form and replacing it with tissue from an entirely different region, Spemann found that the embryo still formed a normal eye, leading him to believe that the optic cup exerted an influence on the cells of the ectoderm, inducing them to form into an eye. To complete this experiment, as well as others, Spemann had to develop a precise experimental technique for operating on objects often less than two millimeters in diameter. In doing so, he is credited with founding the techniques of modern microsurgery, which is considered one of his greatest contributions in biology.

In another series of experiments—conducted in the 1920s—Spemann used a method somewhat less technically demanding to make an even more critical discovery. By tying a thin hair around the jelly-like egg of a newt early in embryogenesis (embryo development), he could split the egg entirely, or squeeze it into a dumbbell shape. When the egg halves matured, Spemann found that the split egg would produce either a whole larva and an undifferentiated mass of cells, or two whole larva (although smaller than normal size). The split egg never produced half an embryo. In the case of the egg squeezed into a dumbbell shape, the egg formed into an embryo with a single tail and two heads. Spemann’s primary finding in these experiments was that if an egg is split early in embryogenesis, the two halves do not form into two halves of an embryo; they either become two whole embryos, or an embryo and a mass of cells.

This led Spemann to the conclusion that at a certain stage of development, the future roles of the different parts of the embryo have not been fixed, which supported his experiments with the newt’s eye. In an experiment conducted on older eggs, however, Spemann found that the future role of some parts of the embryo had been decided, meaning that somewhere in between, a process he called “determination” must have taken place to fix the “developmental fate” of the cells.

In experimenting with transplanting tissue, Spemann found that when an area containing an organizer is transplanted into an undifferentiated host embryo, this transplanted area can induce the host embryo to develop in a certain way, or into an entirely new embryo. Spemann called these transplanted cells organizers, and they include the precursors to the central nervous system. In vertebrates, they are the first cells in a long series of differentiations of which the end product is a fully formed fetus.

Spemann remained at the University of Freiburg until his retirement in the mid-1930s.

Achievements

• Spemann's name will always be associated with his work on experimental embryology. He made himself a master of micro-surgical technique and, working on the relatively large eggs of amphibians he discovered in 1924, the existence of an area in the embryo, the portions of which, upon transplantation into an indifferent part of a second embryo there organized (induced) secondary embryonic primordia. The name «organizer centre» or «organizer» was therefore given by him to those parts. For this discovery of the organizer effect in embryonic development, he was awarded the Nobel Prize in 1935. Some of his methods and instruments are still used by embryologists and neurobiologists today.

Works

More photos

• book

  • Embryonic Development and Induction 1938

Personality

When not busy with his scientific endeavors, Spemann cultivated his love of the liberal arts.

Connections

Spemann married Clara Binder in 1895. The couple eventually had two sons - Fritz and Rudo.

Father:

Johann Wilhelm Spemann

Mother:

Lisinka Hoffmann Spemann

Wife:

Clara Binder

Son:

Fritz Spemann

Son:

Rudo Spemann

References

• The Heritage of Experimental Embryology: Hans Spemann and the Organizer Here is a critical account of the experimental work of German biologist and Nobel laureate Hans Spemann, one of the founders of experimental embryology.
  1988