Freud entered the University of Vienna at age 17. He had planned to study law, but joined the medical faculty at the university, where his studies included philosophy under Franz Brentano, physiology under Ernst Brücke, and zoology under Darwinist professor Carl Claus. In 1876 Freud spent four weeks at Claus's zoological research station in Trieste, dissecting hundreds of eels in an inconclusive search for their male reproductive organs. He graduated with an MD in 1881.