Complex sentence: In the 1840s, with dermatologist Daniel Cornelius Danielssen (1815--1894), Boeck conducted research of leprosy, and the two physicians collaborated on an important treatise called "Om Spedalskhed" (On Leprosy).
Split into simpler sentences: In the 1840s, with dermatologist Daniel Cornelius Danielssen (1815--1894), Boeck conducted research of leprosy. From their studies, the two physicians collaborated on an important treatise called "Om Spedalskhed" (On Leprosy).