The story takes place at the turn of the last century (when indoor plumbing was a luxury). The 18th-century ancestor of spinster cousins Susan & Amy, Cuthbert Frush, whistles "Yankee Doodle." ("Sweet Sue" was from "An Identical Murder.") This is the only instance I know of music playing during E.G. Marshall's remarks. (Instrumental "Yankee Doodle" after Act 1.)