 In 1867 he married Nadezhda Suslova, and two years later relocated to St. Petersburg as an ophthalmologist.His interests soon turned to issues such as public health and conditions of the poor.In the early 1870s he studied hygiene and physiology in Munich, where his instructors were Max von Pettenkofer (1818-1901) and Carl von Voit (1831-1908).