Helen Hayes was the celebrity mystery challenger on "What's My Line?" on April 14, 1957. After the panel correctly guessed her identity, the cast began praising her son, James "one-day-to-be-Danno" MacArthur, who was only beginning his acting career at the time.
Panelist Bennett Cerf, who, by the way, founded Random House publishers, said, "I bet Miss Hayes would like to say something about her son."
Miss Hayes replied, "Oh, I would. He wanted so much to be here tonight, but he has a natural science exam at Harvard tomorrow, so he had to skip it."
At that point, the show's moderator, John Charles Daly, said, "I think this holds only, for those who might not quite understand the reference, James MacArthur, Mr. MacArthur and Miss Helen Hayes' son, is getting to be as famous in the movies as his mother is in the movies and the theater, and I know it must be a source of great pride to you . . ."
Before she left the stage, Miss Hayes asked for donations from the audience to a fund the family established in memory of their daughter, Mary MacArthur, who died of polio in 1949. The fund provided respirators to other victims of polio, as well as to people suffering from other respiratory illnesses.
Mary MacArthur gave James his start in acting when she asked that he appear with her in "The Corn is Green" on stage in Olney, Maryland (1949).