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Darwin Correspondence Project

From Moritz Schiff   8 May 1876

Dear Sir

To Mr Alessandro Garbi of Florence, who interests himself very much for the progress of natural science and especially for what you may allow to call Darwinism, I am indebted for the occasion he offers me, to send you this letter.

In first line many thanks for having sent me your most interesting researches on carnivorous plants.1

As in your book you insist repeatedly on the analogy of the interesting facts you have found concerning the laws of production of the digesting juice in Drosera with what I had found for the gastric juice of the dog, and had called saturation of the stomac by foregoing absorption, it would please you to hear that, notwithstanding the strong opposition my doctrine has found among many physiologists, I am after a carefull repitition of all the experiments fully satisfied that the facts induced by me are true and exact.2

But repeating the experiments under various circumstances and in varied conditions, seaking the source of the contradictions, I found that in one point I must modify my former opinion

I spoke in my lessons of a production of pepsine by absorbed matters.3 This is not quite exact. As I have indicated in the Journal la Nazione several years ago (and this has been confirmed by some researches made in the Laboratory of Heidenhain at Breslau) a substance which I shall call propepsine is constantly present and produced in the stomac, even after the digestion of a very copious meal, but this propesine without beeing modified has no digesting power and acquires it in the living body only by absorption of peptogeneous substances4

But the same modification of the propepsine can be obtained by decomposition produced by a maceration or infusion too much prolongated, or in water, or in some strong acids or in certain salts.— But other salts added in a due proportion to distilled water can hinder the decomposition and extract only the preformed pepsine.

The progress of this decomposition was the cause of some opinions differing from the results of our researches   In general it has been attributed to the stomac too high a digestive power, and some authors misled by theyr method of infusion, have gone so far as to deny that infusion may ever extract whole the pepsine contained in a stomac, even when it were continued for a very long period. Even those who deny the facts of saturation by absorption pretending that the quantity of pepsine never could be exhausted during the life, found theyr opinion on experiments in which they have artificially produced pepsine by maceration.

The best method for preventing all decomposition is the study of digestion in the living stomac by means of the fistula.5 This method, with the precautions I have indicated leads us unvariably to the same results and offers the great advantage of permitting the repetition of the same experiment in the same animal under various conditions.

I have begun some researches on the existence of a propepsine in Drosera, by extracting the leaf with glycerine. My experiments were but few and till now without result.

Another series of facts which has highly interested me is the indication of a sort of reflex action in the Drosera (pg 242 & 276 of your work.)6

As you justly observe we cannot be to cautious in judging this phenomen, which I wished to study in the living plant, by the method we use in animal physiologie7

I dont know wether I can procure me in Geneva the Drosera in a good state. During this last year in Florence my activity has been paralysed by the strong persecutions against the experimental physiology. Next July or towards the end of June I shall leave Florence for occupying the chair of physiology on the newly created school of medecine at Geneva8

I take leave to send to you and to your son Dr. G Darwin (whom they may especially interest) some of my last publications and an elder one by which you may judge how interesting it must be for me, to have a true and undoubtful prove of the existence of reflex action in a plant or rather in what till now we have called plants.9

Excuse the imperfect form of this letter. It is the first I venture to write in your language. | Believe me | Dear Sir | Yours truely | Maurizio10 Schiff

Florence 8/5 76

To Dr Charles Darwin

I hope you have received last year my essay on the method of experiments in living animals, which I sent you by Dr Fraser of Edinburgh11 | Schiff


Schiff’s name appears on CD’s presentation list for Insectivorous plants (see Correspondence vol. 23, Appendix IV).
Schiff’s work on the physiology of digestion (Schiff 1867) was based on his experiments on the digestive processes of dogs: it is cited extensively in Insectivorous plants. In Insectivorous plants, p. 129, CD suggested that mechanical irritation of the glands of Drosera (sundews) stimulated the production of acid, but that the ferment necessary for digestion was secreted only after the absorption of nitrogenous matter.
Schiff made this point in his Leçons sur la physiologie de la digestion (Schiff 1867, 2: lesson 28).
La Nazione was a daily newspaper published in Florence. The Heidenhain laboratory in Breslau in Prussia (now Wrocław in Poland) was under the direction of Rudolf Heidenhain, who carried out research on the inactive precursor of the digestive ferment (Heidenhain 1870). Peptogenous substances (peptogenes) are those substances that transform the precursor that Schiff named propepsin into the digestive agent pepsin.
Schiff’s research on digestive processes, reported in Schiff 1867, was based on observations made by means of surgically produced fistulas in the stomachs of dogs.
In Insectivorous plants, pp. 242–3 and 276–7, CD suggested that the aggregation of protoplasm in the cells of first the glands and then the tentacles of Drosera caused by the presence of carbonate of ammonia or raw meat was a reflex response analogous to that of a nervous system, but different in action from the sensory nerves of animals. He noted that insectivorous plants were the only plants to exhibit this phenomenon. In 1875, Ferdinand Julius Cohn described CD’s discovery of the process of aggregation as ‘the most important in biology of our time’, although he doubted that the aggregated matter was protoplasm (see Correspondence vol. 23, letter from F. J. Cohn, 28 August 1875).
In animal physiology, digestion was studied by means of a surgical fistula in the stomach; CD had earlier suggested to Joseph Dalton Hooker that Hooker should study the digestive processes of Nepenthes (tropical pitcher-plants) by cutting a square hole or fistula in the side of the pitcher (see Correspondence vol. 21, letter to J. D. Hooker, 3 November [1873]). This is probably how Schiff proposed to observe plant digestion. In vivo work ensured that no substances or conditions (such as temperature) were excluded from the experimental set up.
From 1864, Schiff had made clear in La Nazione that he was in favour of vivisection, providing that experiments were conducted on whole animals, and that anaesthetic was used; in 1876, however, Frances Power Cobbe travelled to Florence, where she campaigned against Schiff’s animal experiments, leading him to resign his post and move to the school of medicine in Geneva, which had been opened in 1872 (Feinsod 2011, p. 4).
Schiff probably meant Francis Darwin, not George Howard Darwin; Francis was writing a paper on the process of aggregation in the tentacles of Drosera rotundifolia (the common or round-leaved sundew) in order to test Cohn’s claim that the aggregated matter was not protoplasm (see n. 6, above). There are no articles by Schiff in the Darwin Pamphlet Collection–CUL, nor are any referred to in F. Darwin 1876b.
Schiff used the Italian form of his first name during the years he worked at the University of Florence, and in his Italian publications.
Probably Thomas Richard Fraser, although some time between 1874 and 1877 he left Edinburgh to serve as medical officer of health for mid-Cheshire (ODNB). In 1874, Schiff had published Sopra il metodo sequito negli esperimenti sugli animali viventi nel laboratorio di fisiologia di Firenze (On the method used in experiments on living animals in the physiological laboratory of Florence; Schiff 1874), a revised and augmented edition of his articles on vivisection that had first appeared in La Nazione in 1864 (Dreifuss 1985, p. 291).


Correspondence: The correspondence of Charles Darwin. Edited by Frederick Burkhardt et al. 27 vols to date. Cambridge: Cambridge University Press. 1985–.

Dreifuss, Jean Jacques. 1985. Moritz Schiff et la vivisection. Gesnerus 42: 289–303.

Feinsod, Moshe. 2011. Moritz Schiff (1823–1896): a physiologist in exile. Rambam Maimonides Medical Journal 2: 1–6.

Heidenhain, Rudolf. 1870. Untersuchungen über den Bau der Labdrüsen. Archiv für mikroskopische Anatomie 6: 368–406.

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

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.

Schiff, Moritz. 1867. Leçons sur la physiologie de la digestion, faites au Muséum d’histoire naturelle de Florence. 2 vols. Florence: Hermann Loescher.

Schiff, Moritz. 1874. Sopra il metodo seguito negli esperimenti sugli animali viventi nel laboratorio di fisiologia di Firenze. 2d edition. Florence: Andrea Bettini.


Has repeated his observations and experiments used in Insectivorous plants; finds them sound.

Revises his reference to production of pepsin.

Letter details

Letter no.
Moritz Schiff
Charles Robert Darwin
Sent from
Source of text
DAR 86: B8–9
Physical description

Please cite as

Darwin Correspondence Project, “Letter no. 10500,” accessed on 16 May 2021,

Also published in The Correspondence of Charles Darwin, vol. 24