Which actor did the initial change from Dr. Jekyll to Mr. Hyde without make-up?

Dr. Jekyll and Mr. Hyde is a 1920 horror silent film, produced by Famous Players-Lasky and released through Paramount/Artcraft. The film is based upon Robert Louis Stevenson's novella The Strange Case of Dr Jekyll and Mr Hyde and starring actor John Barrymore.

The early part of Jekyll's initial transformation into Hyde was achieved with no makeup, instead relying solely on Barrymore's ability to contort his face. In one scene, as Hyde reverts to Jekyll, one of Hyde's prosthetic fingers can be seen to fly across the screen, having been shaken loose by Barrymore's convulsions. The character of Millicent Carew does not appear in Stevenson's original story, but in the 1887 stage version by Thomas Russell Sullivan starring Richard Mansfield. This 1920 film version used the play's concept of Jekyll being engaged to Carew's daughter, and Hyde beginning a dalliance with a dance-hall girl.