Courtesy Valeriy
The X-Ray plates used for recording were rectangular sheets. They would be cut into a circle shape with scissors. To be played on a gramophone or record player, they would need a central spindle hole. Often this was made by applying a lit cigarette - the perfect size.
Courtesy Yuriy Boyarintsev
The lower example shown below ('Don't Wake Me' from the opera Werther) has two holes - the second was to keep the plate in place during the writing process on certain devices provided with a second spindle for the purpose.