2018 Surratt Society Conference

[ReignetteC]

I am glad to have returned to the Surratt Conference after a three-year hiatus (not planned). The presentations were all enjoyable and some were thought-provoking. I am sure that after I review my notes I will have several questions for the experts here. But for now, here is one:
The gentleman who gave the engaging presentation called, "Dr. Samuel Mudd: The Man, the Martyr, and the Movies," said that Mudd charged Booth the grand sum of $25 to set his leg. When someone in the audience asked about the evidence of such, I believe the speaker attributed it to oral provenance. Any thoughts?