Most of them have their origin in a nucleus, the nucleus of the posterior commissure (nucleus of Darkschewitsch), which lies in the central gray substance of the upper end of the cerebral aqueduct, in front of the oculomotor nucleus.

He is remembered for his description of the nucleus of the posterior commissure, also known as the "nucleus of Darkshevich", defined as a cell group located in the central gray substance of the upper end of the cerebral aqueduct, in front of the oculomotor nucleus.