In 1754, at the age of 25, soon after he was ordained he became professor of logic, metaphysics and Greek in the University of Reggio. In 1763, he was moved to the University of Modena, where he continued to teach with great assiduity and success, but devoted his whole leisure to natural science. There he also served as a priest of the Congregation Beata Vergine and S. Carlo. He declined many offers from other Italian universities and from St Petersburg until 1768, when he accepted the invitation of Maria Theresa to the chair of natural history in the University of Pavia, which was then being reorganized. He also became director of the museum, which he greatly enriched by the collections of his many journeys along the shores of the Mediterranean Sea. In June 1768 Spallanzani was elected a Fellow of the Royal Society and in 1775 was elected a foreign member of the Royal Swedish Academy of Sciences.