The present study explores some of the mechanisms at work in the award of the Nobel Prize in medicine or physiology during the period 1901-1950. In his will, Nobel mentioned three explicit criteria for the Nobel Committees, but an examination of the fate of German biochemist Carl Neuberg reveals how implicit criteria came to be added. For example, the Nobel Committees in Medicine and Chemistry were challenged by the emergence of new disciplines such as biochemistry, and in response began to rotate awards around different specialities.