The Story of Louis Pasteur (1936)
When Ann asks Clint if research scientists Pasteur or Ehrlich gave up on their work, Clint reponds that he doesn't know since he hadn't been to the movies recently.
Features outtakes from the film
clips are shown
The "must wash our hands" scene in A Day at the Races was a parody of this Louis Pasteur biography made two years earlier. Groucho even says "Crazy? That's what they said about Pasteur!".