[Magnus Hirschfeld and monism: mutual fertilization or exchange of errors?].

When Ernst Haeckel was buried in Jena on February 12th, 1919, some of his supporters and followers were allowed to make speeches. One of them was the sexologist Magnus Hirschfeld, although he had entered the German-Monist-Club only six years after its foundation in 1906. He became one of the most important monists, because he worked in the fields of sexuality and eugenics, and was head of discourse for many years. But he imported some ideas of his colleagues for his own studies, especially the neolamarckism. The failure of this theory had decisive consequences for monism and sexology, as well.