To William Ogle   13 April [1871]

My dear D^r. Ogle

I must tell you a little fact about the platysma. I made one of my sons try to shudder, & the platysma didnt act at all. The next morning he was standing quite undressed with his hand accidentally on the lower part of the throat & he shivered from cold. He then suddenly felt the platysma contract, & he said it felt just as if his hand was on another person’s body.

M^r. J. Wood, who has attended so closely to the muscular system, has written to me (making I believe the 5^th. communication) about my blunder in calling the platysma involuntary; & he incidentally says he has seen it contracting during vomiting & screaming, & under rage & disgust; also during a shudder.¹ I have begged him to observe whether it acts under extreme fear. In answer, he says he does not believe it does then act but will observe.²

Thus by your & his kind aid I think I shall get a pretty full history of the action of this abominable muscle.³

yours very sincerely | Ch. Darwin