From James Dixon   7 May 1880

Sir,—

May I take the liberty of drawing your attention to a trifling—very trifling—inaccuracy which occurs in your Descent of Man? (1871, i, 19)— You say “the platysma myoides … cannot be voluntarily brought into action.” In my own case this muscle is as much under control as any other in my body.¹ I can use either lateral portion separately, or both portions together. The contraction influences the skin as far upwards as the angles of the mouth, both of which become slightly depressed; and in a downward direction the action extends far enough to move the nipples very slightly. I have known several persons who had the platysma under control, but I never met with anyone in whom this was the case to so great an extent as in myself.

I may observe that I know something about muscles inasmuch as I was Demonstrator of Anatomy at S^t Thomas’s Hospital during ten years.² I was a standing wonder to my pupils, who were highly amused at my ability to use many muscles over which they had not the slightest control. I could—and can—move everyone of my facial muscles; and my palmaris brevis is as active now, when I am past 60, as it was 40 years ago.³

I hope these confessions will not cause you to regard me as the “missing link.”

Excuse my thus addressing you, and believe me to be very faithfully y^rs. | James Dixon

Charles Darwin Esq. F.R.S. | &c &c