 He graduated "magna cum laude" with Harting in 1874 with a study on nermertine worms.In 1875–1882 he worked at the "Rijksmuseum van Natuurlijke Historie" in Leiden, where he was the curator of ichthyology and herpetology, and in 1882 became professor at Utrecht.In 1890–1891 he traveled in Java, Sumatra, and Borneo, where he made embryological studies, notably on the tarsier.