In 1897 he became an assistant to Max Jaffé in the laboratory of medicinal chemistry and experimental pharmacology at the University of Königsberg.
In 1914 he was appointed professor of pharmacology at the newly established University of Frankfurt.
[1] He is remembered for his extensive biochemical research of several amino acids, especially tryptophan.
[2] In 1904 he isolated kynurenic acid from the urine of dogs that had been fed tryptophan.
[3] His other work included studies on the water exchange between body tissues and blood, on the formation on lymph,[1] and with chemist Karl Spiro, he conducted investigations of blood coagulation.