To William Turner 1 February 
Down. | Bromley. | Kent. S.E.
My dear Sir
I thank you cordially for all your full information, & I regret much that I have given you such great trouble at a period when your time is so much occupied.1 But the facts are so valuable to me that I cannot pretend that I am sorry that I did trouble you; & I am the less so, as from what you say, I hope you may be induced some time to write a full account of all rudimentary structures in man: it would be a very curious & interesting memoir. I shall at present give only a brief abstract of the chief facts which you have so very kindly communicated to me, & will not touch on some of the doubtful points.2 I have received far more information than I ventured to anticipate.
There is one point, which has occurred to me, but I suspect there is nothing in it. If, however, there shd. be, perhaps you will let me have a brief note from you; & if I do not hear I will understand there is nothing in the notion— I have included the down on the human body & the lanugo on the fœtus as a rudimentary representation of a hairy coat.3 I do not know whether there is any direct functional connection* between the presence of hair & the panniculus carnosus, but both are superficial & would perhaps together become rudimentary.4 I was led to think of this by the places, (as far as my ignorance of anatomy has allowed me to judge) of the rudimentary muscular fasciculi, which you specify.— Now some persons can move the skin of their hairy heads, & is this not effected by the panniculus? How is it with the eyebrows? You specify the axillæ & the front region of the chest & lower part of scapulæ: now these are all hairy spots in man.5 On the other hand the neck, and as I suppose the covering of the gluteus medius,6 are not hairy; so, as I said, I presume, there is nothing in this notion.— If there were, the rudiments of the Panniculus ought perhaps to occur more plainly in man than in woman.—
With very sincere thanks for all that you have done for me, & for the very kind manner, in which you granted me your favour, pray believe me | My dear Sir | Yours very sincerely | Ch. Darwin
*To put the question under another point of view: is it the primary or aboriginal function of the panniculus to move the dermal appendages or the skin itself?
P.S. If the skin on the head is moved by the Panniculus, I think I ought just to allude to it, as some men alone having power to move the skin, shows that the apparatus is generally rudimentary.
Thanks for information about rudimentary organs. Asks about rudimentary character of human hair and panniculus carnosus.