Events of the past few years have accustomed us to the knowledge that the position of "non-Aryan" scientific colleagues in official positions in the German Reich has become intolerable, even in the few cases where they have not been expelled from office.^[1] Now a new situation is developing which may be fraught with considerable danger to the continued co-operation of workers in other countries with their German colleagues. This new development carried to the limit can only result in the isolation of German men of science in all matters of international organisation.