Taking the example of the renowned German surgeon of the bile ducts Hans Kehr (1862-1916) and two cases published by him, the possibilities and limitations of neurosurgical activity within the frame of general surgery at the turn of the 19th to the 20th century at a private surgical hospital are outlined. A typical factor of the early history of specialised medical fields can be considered to be the successful autodidactic performance of almost all major interventions in all parts of the body and at the same time the turn to a topographically or pathophysiologically determined field of working. Here, peak performances in a partial field could still be well connected with a maintenance of the shole field. Kehr's actions in the practical-surgical treatment of the lesions of the skull corresponded in their basic conceptions to our present ideas. The further development, however, showed that the responsible and successful surgery in a special field-in the case of Kehr the surgery of the bile ducts-could only be performed with a far-reaching renunciation of other surgical activities.