He subsequently worked as a military physician, reaching the rank of Generaloberarzt, including as a researcher at the Robert Koch Institute for Infectious Diseases in Berlin (1902–1905) and as an adviser on hygiene and epidemiology at the Prussian Ministry of War.
He obtained the Habilitation in 1914 at Leibniz University Hannover and became a Professor in 1916.
From 1920 he worked at the National Institute for Experimental Therapy as a researcher and head of department.
His research focused on many areas of microbiology, particularly immunology.
He was noted especially for his research on cholera and typhus vaccines.