[Odón de Buen: forty-five years of commitment to the university]

The aragonese naturalist Odón de Buen y del Cos for twenty-two annual academic courses professor of natural history at the University of Barcelona and for twenty-three of the University of Madrid. Strong supporter of Darwin's evolutionary theory, experimental work in the field and laboratory, in this paper puts the value of their efforts, as an educator, to popularize the natural sciences and thus separated from the concerns, superstition and fanaticism, which they were basic reasons of the moral and material backwardness in which Spain was found.