[2] 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.

[4] 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.

[5] 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".

[6] 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.

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.

[3] 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 micro-surgery.

Spemann was appointed Professor of Zoology and Comparative Anatomy at Rostock in 1908 and, in 1914, associate director of the Kaiser Wilhelm Institute of Biology at Dahlem, Berlin.

Drawing upon the recent work of Warren H. Lewis[3] and Ethel Browne Harvey,[7] he turned his skills to the gastrula, grafting a "field" of cells (the Primitive knot) from one embryo onto another.

Despite his modern reputation, Spemann continued to entertain neo-vitalist "field" analyses similar to those of Hans Driesch, Gurwitsch and Harold Saxton Burr.