skip to content

Darwin Correspondence Project

From T. L. Brunton   28 February 1874

23 Somerset St. Portman Sq | London W.

Feby 28th. 1874

Dear Sir

I have delayed writing you because I was unwilling to do so until I could give you some definite information.1 I have been unable to find any experiments upon the digestion of chlorophyll & therefore have tried some myself. For some time I could not obtain any chlorophyll & have just finished my observations. The chlorophyll I used is that obtained during the manufacture of green extracts by the process given in the British Pharmacopœia.2 I placed a piece the size of a pea in each of 5 test tubes.

No 1 contained Glycerine extract of dogs pancreas and water
2 ........... dogs stomach with dilute HCl .02%
3 ........... glycerine & water
4 ........... dilute acid
5 ........... dilute acid alone

They remained for five days at a temperature of 37oC. The liquid acquired a slightly brown colour & the pieces of chlorophyll became swollen & ragged but they did not diminish in size   The chlorophyll in No. 1 fell to a powder but this was partly due to shaking. A second experiment with the glycerine extract of pancreas has given an entirely negative result. The glycerine extracts are both active. That of the stomach digests fibrine with extreme rapidity & had a piece of blood fibrin been used instead of chlorophyll it would have disappeared in less than ten minutes, instead of being unaltered after five days. Chlorophyll also seems to be little affected by the juices of the alimentary canal in the human subject for as far as my experience goes the chlorophyll of spinach communicates a green colour to the faeces. The same appears to me to be the case in cows, if one may judge from the appearance of the faeces & probably the black colour of the excreta in goats & sheep is also due to chlorophyll at least in part. Chlorophyll as obtained by me (from a friend) is of a very dark green, almost black colour.3

In regard to Chondrin I have succeeded in finding a few references. A. M. Thurn Moleschott’s Untersuchungen V. p 315–3184 finds that dried cartilage (or tendon) is dissolved by dilute hydrochloric acid either alone or with pepsin in 3 days gelatin is dissolved in 2–6 hours. Both are acted on in much the same time & way by dilute acid of .4 per cent when alone as when pepsin is also present (The acid is too strong)   Metzler, working under Heidenhaur’s direction finds that gastric juice with dilute acid dissolves cartilage & deprives the solution of its power to gelatinize.5 This action is due to the pepsin for it is destroyed

⁠⟨⁠    ⁠⟩⁠ Giessen quoted in Scu⁠⟨⁠  ⁠⟩⁠ ⁠⟨⁠    ⁠⟩⁠ p 110 & 153 Meissner & Ki⁠⟨⁠  ⁠⟩⁠ ⁠⟨⁠    ⁠⟩⁠ find that chondrin splits ap⁠⟨⁠  ⁠⟩⁠ ⁠⟨⁠    ⁠⟩⁠ sugar d⁠⟨⁠u⁠⟩⁠ring digestion Hen⁠⟨⁠  ⁠⟩⁠ ⁠⟨⁠    ⁠⟩⁠ Zeitschrift 3te Reihe XIV p. 31⁠⟨⁠6⁠⟩⁠6 ⁠⟨⁠    ⁠⟩⁠ I cannot find any experiments on the nutritive value of chondrin. I send a copy of the Me⁠⟨⁠dic⁠⟩⁠al Record containing an abstract of some experiments of Voit on gelatin but I do not know whether it will be of any service or not.7 I will keep a look out & if I meet with any experiments on the nutritive value of ⁠⟨⁠c⁠⟩⁠hondrin I ⁠⟨⁠3 lines missing⁠⟩⁠ example less striking ⁠⟨⁠    ⁠⟩⁠ ⁠⟨⁠re⁠⟩⁠marks is the countenance ⁠⟨⁠    ⁠⟩⁠ Holman Hunt’s picture of ⁠⟨⁠    ⁠⟩⁠ of Death now ⁠⟨⁠ex⁠⟩⁠hibiting ⁠⟨⁠    ⁠⟩⁠ side of the face it seems to me has an expression of weariness alone while the left side expresses little or no w⁠⟨⁠ear⁠⟩⁠iness but a curious mixture of longing & energy.8 The express⁠⟨⁠io⁠⟩⁠n of the two sides of the face can be voluntarily rendered quite different by some persons. I can do so to a considerable extent myself, and some tim⁠⟨⁠e⁠⟩⁠ ago I believe a man gave an en⁠⟨⁠tert⁠⟩⁠ain⁠⟨⁠ment⁠⟩⁠ ⁠⟨⁠    ⁠⟩⁠ Egyptian Hall9 or some ⁠⟨⁠    ⁠⟩⁠ of amusement by ex⁠⟨⁠  ⁠⟩⁠ ⁠⟨⁠    ⁠⟩⁠ in this respect. ⁠⟨⁠    ⁠⟩⁠ Russell, Deputy Surveyor General of Canada10 tells me that some years ago an acquaintance of his used greatly to torment the superior of his department by making odd faces at his comrades while the side of his face which was turned towards the superior maintained the profoundest gravity.

The expression of the two sides of the face is also different under certain pathological conditions such as hemicrania. This I have ⁠⟨⁠    ⁠⟩⁠ obser⁠⟨⁠ved⁠⟩⁠ in myself⁠⟨⁠    ⁠⟩⁠ face app⁠⟨⁠  ⁠⟩⁠ed by the ⁠⟨⁠    ⁠⟩⁠ appearance of ⁠⟨⁠    ⁠⟩⁠ ⁠⟩⁠ other side was perfectly ⁠⟨⁠n⁠⟩⁠ormal. The recurrence of a different expression on the two sides of the face as an indication of mixed emotions is noticed by Dumas in his Memoirs of a Physician where he describes Rousseau as listening to the performance of one of his pieces by the king & queen. Delighted at the favour done him by these royal personages but disgusted by the miserable execution of his piece he was like a monkey eating11 ⁠⟨⁠several words⁠⟩⁠ one side of ⁠⟨⁠several words⁠⟩⁠ other. Althoug⁠⟨⁠h⁠⟩⁠ ⁠⟨⁠several words⁠⟩⁠ that Dumas is ⁠⟨⁠several words⁠⟩⁠ of a popular expression which is to be heard I think in England as well as France, yet the expression seems to indicate that the facts have been observed by somebody & probably by many. Indeed the difference of expressions on the two sides of the face seems to me to appear in sneering. A one-sided sneer is much more irritating than a double one, if I may judge from practice ⁠⟨⁠several words⁠⟩⁠ one ⁠⟨⁠several words⁠⟩⁠ disgust ⁠⟨⁠several words⁠⟩⁠ ⁠⟨⁠t⁠⟩⁠hat expression ⁠⟨⁠2 or 3 words⁠⟩⁠ which distinguishes the single sneer.

The portrait of Locke, Fig 60 in Piderit’s Mimik und Physiognomik (1867)12 shows a combination which I have frequently observed in my own face when looking at it in the mirror full in front so that the expression was not due to one side of the face being seen partially & the other completely. The one side the right is contented & placid, the other the left restless anxious & even pained. I am left handed & it is the right side of my face which is restless. I see that ⁠⟨⁠several words⁠⟩⁠ as an example ⁠⟨⁠several words⁠⟩⁠ with a low f⁠⟨⁠  ⁠⟩⁠ ⁠⟨⁠several words⁠⟩⁠ know the eye ⁠⟨⁠several words⁠⟩⁠ I am inclined to think that the expressions of the two side of the face differ most frequently in persons with small heads & of a nervous temperament. The Christ in Holman Hunt’s picture is a typical example of the temperament I mean. I have no portrait of Byron13 at hand but he also belongs to the class & ought to show a difference of expression unless at perfect rest.

⁠⟨⁠several words⁠⟩⁠ ⁠⟨⁠s⁠⟩⁠ome interest ⁠⟨⁠several words⁠⟩⁠ serpent worship ⁠⟨⁠several words⁠⟩⁠ struck with your ⁠⟨⁠several words⁠⟩⁠ of the horr⁠⟨⁠or⁠⟩⁠ monkeys [have of] snakes. I supp⁠⟨⁠ose⁠⟩⁠ this horror would become the basis of a religion in any race of monkeys which developed far enough to have one & is probably the origin of the worship which was formerly so extensively diffused among mankind. The tree as the representative of good is easy to understand & the serpent, almost the only enemy the arboreal monkeys need dread, as the type of evil; but the serpt as the healer I cannot make out. When monkeys learned the use of fire & (thus?) became elevated to the rank of men they would worship fire ⁠⟨⁠several words⁠⟩⁠ descent of ⁠⟨⁠several words⁠⟩⁠ his creeds ⁠⟨⁠several words⁠⟩⁠ troubling you with ⁠⟨⁠t⁠⟩⁠his long letter a great part of which I find is taken up with speculations new to me but the last of them at any rate probably old & well known to others but your former kind letter has emboldened me to mention my ideas to you and in return for your valuable time which I have consumed I shall be ⁠⟨⁠several words⁠⟩⁠ for you ⁠⟨⁠several words⁠⟩⁠ such infor⁠⟨⁠mation⁠⟩⁠ ⁠⟨⁠2 or 3 words⁠⟩⁠ want & the opportunities of consulting libraries &c in London enable me to secure.

I remain truly dear Sir | Yours very faithfully | T. Lauder Brunton

CD annotations

4.1 In regard … destroyed 4.8] crossed blue crayon
5.1 ⁠⟨⁠    ⁠⟩⁠ Giessen … ⁠⟨⁠c⁠⟩⁠hondrin 5.00] scrossed blue crayon
8.00 the opportunities … secure 8.00] crossed blue crayon
Top of letter: ‘Chlorophyll’ blue crayon


Brunton had offered to carry out experiments on the digestibility of chlorophyll and chondrin for CD (Correspondence vol. 21, letter from T. L. Brunton, 2 December 1873).
Brunton refers to a process for producing extracts from green-leaved plants. The leaves were bruised in a stone mortar and the juice pressed out; the juice was heated gradually to 130oF (54oC); and the ‘green colouring matter’ separated out using a calico filter. See, for example, British pharmacopœia (1867), p. 112.
CD reported Brunton’s findings in Insectivorous plants, pp. 126.
Brunton refers to A. Im Thurn and Im Thurn 1858, published in Jacob Moleschott’s periodical Untersuchungen zur Naturlehre des Menschen und der Thiere. A. Im Thurn has not been identified.
Brunton refers to Eduard Metzler’s dissertation, Beiträge zur Lehre von der Verdauung des Leims, der leimgebundenen Gewebe und des Knorpels (Contributions to the theory of digestion of collagen, collagenous tissue, and cartilage; Metzler 1860), and to Rudolf Heidenhain.
Georg Meissner’s experiments on digestion were published in the Zeitschrift für rationelle Medicin, also known as Henle und Pfeufer’s Zeitschrift (Meissner et al. 1859–62). His speculation that chondrin split into gluten and sugar appears in the Zeitschrift für rationelle Medicin 14 (1862): 316–19.
In Insectivorous plants, p. 112 n., CD cited Brunton’s article, ‘Voit on the nutritive value of gelatin’ in Medical Record, 22 January 1873, pp. 36–7. CD’s copy is in DAR 58.2: 19.
Hunt’s The shadow of death was exhibited in a Bond Street gallery from December 1873 to August 1874; it depicted Christ and his mother in a carpenter’s workshop. Two versions of the painting exist; the larger one was the one exhibited in Bond Street and is now in the Manchester City Galleries. (ODNB s.v. Hunt, William Holman). The other is in the collection of Leeds Museums and Galleries.
The Egyptian Hall was in Piccadilly, London.
Alexandre Dumas, père, wrote in Dumas 1847, 3: 85: ‘Rousseau, half flattered by the monarch’s good memory, half wounded by his detestable execution, looked like a monkey nibbling an onion—crying on one side of his face and laughing on the other.’ Brunton refers to Jean Jacques Rousseau, Louis XV of France, and Louis’s wife, Marie Leszczyńska.
There is an annotated copy of Theodor Piderit’s Mimik und Physiognomik (Piderit 1867) in the Darwin Library–CUL (Marginalia 1: 675–7). The illustration is of John Locke.


British pharmacopœia (1867). London: Spottiswoode & Co. 1867.

Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 29 vols to date. Cambridge: Cambridge University Press. 1985–.

Dumas, Alexandre. 1847. Memoirs of a physician. Part I, Joseph Balsamo. 3 vols. London and Belfast: Simms & M’Intyre.

Im Thurn, A. 1858. Physiologisch-chemische Studie über Leim und Leimbildner. Untersuchungen zur Naturlehre des Menschen und der Thiere 5: 315–18.

Insectivorous plants. By Charles Darwin. London: John Murray. 1875.

Marginalia: Charles Darwin’s marginalia. Edited by Mario A. Di Gregorio with the assistance of Nicholas W. Gill. Vol. 1. New York and London: Garland Publishing. 1990.

Metzler, Eduard. 1860. Beiträge zur Lehre von der Verdauung des Leims, der leimgebundenen Gewebe und des Knorpels. (Inaugural dissertation.) Giessen: Keller.

ODNB: Oxford dictionary of national biography: from the earliest times to the year 2000. (Revised edition.) Edited by H. C. G. Matthew and Brian Harrison. 60 vols. and index. Oxford: Oxford University Press. 2004.

Piderit, Theodor. 1867. Wissenschaftliches System der Mimik und Physiognomik. Detmold: Klingenberg’sche Buchhandlung.


Reports negative results of his experiments on digestion of chlorophyll by Drosera and by animals. [See Insectivorous plants, p. 126.]

Sends references for chondrin.

Letter details

Letter no.
Thomas Lauder Brunton, 1st baronet
Charles Robert Darwin
Sent from
London, Somerset St, 23
Source of text
DAR 58.1: 47–8, DAR 160: 340
Physical description
AL inc †

Please cite as

Darwin Correspondence Project, “Letter no. 9322,” accessed on 23 May 2024,

Also published in The Correspondence of Charles Darwin, vol. 22