At 15, Peter glimpsed some modern German art at an odd venue: a Munich police station, where he saw paintings by Wassily Kandinsky, Paul Klee and Max Beckmann — a small sampling of the 20,000 works that the Nazis, then newly in power, would remove from state museums and declare degenerate art.

As the Nazis’ persecution of Jews increased, including measures that forced Dr. Selz to treat only Jewish patients, Peter left Germany in 1936 on his own and went to America through the help of family members who owned the Rheingold brewery in Brooklyn.

After attending high school and then Columbia University for a year, he went to work at the brewery scrubbing beer vats to help support his parents, who had arrived with his brother Edgar in 1940. (Peter also had a half brother.)

While miserable at the brewery — he was beaten by German-American co-workers, who were Nazi sympathizers — he furthered his art education by spending time in Manhattan with Alfred Stieglitz, the photographer and art gallery owner, who was a distant relative.

“He sort of took me on and showed me what modern art was about,” Mr. Selz said.

Mr. Selz served in the Army infantry and the Office of Strategic Services, the United States’ wartime intelligence agency, before enrolling in the University of Chicago, where he took an accelerated course of studies on the G.I. Bill that allowed him to bypass undergraduate work. There, he earned a master’s in art history and a Ph.D in modern art history.

Mr. Selz later turned his doctoral dissertation into a book, “German Expressionist Painting” (1957). By then he had been chairman of the art department at Pomona College, near Los Angeles, since 1955. The book’s publication coincided with an exhibition on German Expressionism that he organized at the college. He remained there until MoMA hired him.