Ɛpsilon

To R. A. Vance   4 December 1877

Down, | Beckenham, Kent. | Railway Station | Orpington. S.E.R.

Dec 4 1877

Dear Sir,

I am obliged for your long & valuable letter.1 I am too ignorant of anatomy to form any decided opinion on the subject; but if I had met with your statements I should have been inclined to attribute the spiral folds to reversion & the valves to the partial abortion of the fold. I should have formed this opinion from the analogous structure in fishes of the most generalised kind, & to the great variability of the parts in question.2 Could you not procure an oppossum & examine the lower intestine; for if it presents no trace of the structure in question I should hesitate if I were in your place to allude to reversion.3 If marsupials do exhibit any vestige I would examine one of the lower placental mammals a rabbit for instance & afterwards a monkey. If you could satisfactorily prove the nature of these remnants it would be a conclusion of much interest4

As I have already referred to my ignorance of anatomy you will of course not refer to the remark which I have hazarded—

Dear Sir | Yours faithfully | Ch. Darwin

LS

2
CD refers to the scroll or spiral valves of some fishes, such as sharks, with very short intestines; the valves increase the absorptive surface of the organ. Vance had suggested that the valves of Houston in the human rectum were rudimentary features and noted that the structure and number of valves was variable, based on his observations of several human specimens (see letter from R. A. Vance, 12 November 1877 and n. 2).
3
Opossums are the only marsupials native to North America (family Didelphidae); the range of the Virginia opossum (Didelphis virginiana) extends into Ohio, the state in which Vance lived.
4
Vance had quoted John Houston’s report noting similar structures in the caecum of rabbits and large intestine of snakes and dogfish (see letter from R. A. Vance, 12 November 1877 and nn. 4 and 5). Vance was evidently unaware that in the only other study where human and mammalian rectal organs were compared, ‘Ueber die Falten des Mastdarms’ (On the folds of the rectum; Baur 1863, pp. 27–8), no similar valves were found in any of the observed animals, which ranged from the wombat (a marsupial), wolf, and bear to the lemur and chimpanzee.

Please cite as “DCP-LETT-11269,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-11269