My dear M^r Bowman

It is extremely kind of you to take so much trouble for me. I will copy out all that Bell says, so that you need take no trouble in referring to his works.— In the Anatomy of Expression 3^rd Ed. page 105 he says “During every violent act of expiration (as in cases quoted in my last note) the eyeball is firmly compressed by the fibres of the orbicularis; & this is a provision for supporting & defending the vascular system of the interior of the eye from a retrograde impulse communicated to the blood in the veins at that time .... the blood is even regurgitated into the minute branches. Were the eye not properly compressed at that time, & a resistance given to the shock, irreparable injury might be inflicted on the delicate textures of the interior of the eye— Hence we see reason for the closed state of the eyelids & the wrinkling of the surrounding skin” &c. He then quotes from his own Nervous System p. 175, as follows “If we separate the eyelids of a child to examine the eye, while it cries & struggles with passion, by taking off the natural support to the vascular system of the eye, & the means of guarding it against the rush of blood then occurring, the conjunctiva becomes suddenly filled with blood & the eyelids everted.’ The Nervous System is not his 4^to publication, but an Essay appended to the 2^nd Ed. of the Anat. of Exp. which I have not as yet been able to see.²

I remember noting more than 20 years ago with one of my own infants, that sometimes the first sign of a fit of passion was its naked head becoming red just before even a frown commenced.³ I am very anxious to have some confirmation of Bell’s statement of the cause of the contraction of the orbicularis during screaming &c, as it is the key-stone of a whole class of expressions, & I am unwilling to trust to a single observer however good he may be.⁴

I shall hereafter be very curious to hear whether you believe that the whiteness of the eyes in scrofulous ophthalmia is any way caused by the strong pressure of the orbicularis.⁵

I shall be equally curious to learn y^r conclusion in regard to the relation between the contraction of the orbicularis & the secretion of at least some few tears.

With cordial thanks for your most kind assistance—I remain yours very sincerely | Charles Darwin.

P.S. | Perhaps it is worth notice that hard voluntary contraction of the Orbicularis does not cause secretion of tears.

At least several of my children contracted this muscle till their eyes ached, & their eyes were hardly moist; whilst a good yawn &c will make the tears almost overflow.⁶ Can different muscular fibrils act or is it difference of a voluntary & involuntary contraction?