As the dark events foreshadowing World War II pushed eminent Jewish scientists out of Europe, Clarke opened his laboratory to refugee biochemists, among them E. Brand, Erwin Chargaff, Zacharias Dische, K. Meyer, David Nachmansohn, Rudolph Schoenheimer, and Heinrich Waelsch [REF].
As head of Columbia's Biochemistry Department, Clarke took a personal interest in graduate students, of whom he demanded rigorous qualifications prior to admission.