Correspondence of Dr. George M. Mackenzie with friends and associates of Karl Landsteiner; memoranda of conversations; notes and recollections of Landsteiner by Thomas M. Rivers, 1944-1952, and by Max Neuberger; Landsteiner's departmental reports at Rockefeller Institute, 1923-1943; correspondence on publications. There is much material on immunology, the study of blood, the Nobel award, 1930, antisemitism, and the Vienna medical schools.