FEA&. CHAP. XII. cle sometimes contracts, perhaps for the sake of opening the mouth widely, when the breathing is rendered diffi- cult by disease, and during the deep inspirations of cry- ing-fits before an operation. Now, whenever a person starts at any sudden sight or sound, he instantaneously draws a deep breath; and thus the contraction of the platysma may possibly have become associated with the sense of fear. But there is, I believe, a more efficient relation. The first sensation of fear, or the imagination of something dreadful, commonly excites a shudder. I have caught myself giving a little involuntary shudder at a painful thought, and I distinctly perceived that my platysma contracted; so it does if I simulate a shudder. I have asked others to act in this manner; and in some the muscle contracted, but not in others. One of my sons, whilst getting out of bed, shuddered from the cold, and, as he happened to have his hand on his neck, he plainly felt that this muscle strongly contracted. He then voluntarily shuddered, as he had done on former occasions, but the platysma was not then affected. Mr. J. Wood has also several times observed this muscle con- tracting in patients, when stripped for examination, and who were not frightened, but shivered slightly from the cold. Unfortunately I have not been able to ascertain whether, when the whole body shakes, as in the cold stage of an ague fit, the platysma contracts. But as it cer- tainly often contracts during a shudder; and as a shud- der or shiver often accompanies the first sensation of fear, we have, I think, a clue to its action in this latter case.23 Its contraction, however, is not an invariable 23 Duchenne takes, in fact, this view (ibid. p. 45), as he attributes the contraction of the platysma to the shiver- ing- of fear (frisson de la peur); but he elsewhere compares the action with that which causes the hair of frightened quadrupeds to stand erect; and this can hardly be consid- ered as quite correct.