To T. H. Huxley 16 February 1
Down. | Bromley. | Kent. S.E.
My dear Huxley
I called twice in Jermyn St. but unfortunately found you once lecturing & secondly out.—2 It is by no means the carpal or tarsal bones which are increased in number, but generally only the digits & metacarpals.3 Indeed until the whole hand becomes doubled or bifurcated, it appears that the carpal bones are not increased. This same doubling puzzles me; but yet, I think, the wonderfully strong inheritance & thrice repeated growth shows that there is something in the case.4 May I say that the digits, (divided by many joints in the rays) are indefinite in number & very generally more than five in the pectoral fins of Fishes? How are Sharks &c in this respect? These being one of oldest orders would be best.—5
Now there is one other point, for which I shd. be very glad of information & bears on a remark made by you: I am told that Roget (no good authority) says in Bridgewater Treatise that in Frogs or Toads there is a rudiment of a sixth digit.6 Have you any specimen in spirits? I think I remember a tubercle behind. If there is one, could you spare time to dissect this tubercle & see whether in bone or other respect there is any reason to suppose that this really is rudiment of 6th digit. I have heard vaguely of two cases of six-toed frogs on hinder limb. If it should turn out a rudiment, you will, I know, allow me to quote you.
Ever yours | C. Darwin
It is not carpal or tarsal bones that are increased [in six-fingered men] but generally only the digits and metacarpals.
Pectoral fins of fish and sharks.
Asks THH to check P. M. Roget’s statement that there is a rudiment of a sixth digit in frogs.
[P.S. missing from original.]
Please cite as
Darwin Correspondence Project, “Letter no. 3987,” accessed on 8 December 2016, http://www.darwinproject.ac.uk/DCP-LETT-3987