To F. C. Donders 7 July 1874
Down. | Beckenham Kent.
July 7— 74—
My dear Prof Donders.
My son George writes to me that he has seen you, & that you have been very kind to him for which I return you my cordial thanks.—1 He tells me on your authority— of a fact which interests me in the highest degree, & which I much wish to be allowed to quote. It relates to the action of one millionth of a grain of Atropine on the eye.— Now will you be so kind whenever you can find a little leisure to tell me whether you yourself have observed this fact, or believe it on good authority— I also wish to know what proportion by weight the atropine bore to the water of solution, & how much of the solution, was applied to the eye— The reason why I am so anxious on this head is that it gives some support to certain facts repeatedly observed by me—with respect to the Action of Phosphate of Ammonia on Drosera— The of a grain absorbed by a gland clearly makes the tentacle which bears this gland become inflected; & I am fully convinced that of a grain of the Crystallized salt. (i e containing about of its weight of water of crystallization) does the same.2 Now I am quite unhappy at the thought of having to publish such a statement It will be of great value to me to be able to give any analogous facts in support.3 The case of Drosera is all the more interesting as the absorption of the salt or any other stimulant applied to the gland causes it to transmit a motor influence to the base of the tentacle which bears the gland—
Pray forgive me for troubling you, & do not trouble yourself to answer this until your health is fully reestablished—
Pray believe me. | your’s very sincerely— | Charles Darwin.
Footnotes
Bibliography
Insectivorous plants. By Charles Darwin. London: John Murray. 1875.
Summary
Asks about the effect of atropine on the eye. Is interested in parallel case: influence of phosphate of ammonia on glands of Drosera.
Letter details
- Letter no.
- DCP-LETT-9535
- From
- Charles Robert Darwin
- To
- Frans Cornelis (Franciscus Cornelius) Donders
- Sent from
- Down
- Source of text
- DAR 143: 417
- Physical description
- C 4pp
Please cite as
Darwin Correspondence Project, “Letter no. 9535,” accessed on 28 March 2024, https://www.darwinproject.ac.uk/letter/?docId=letters/DCP-LETT-9535.xml
Also published in The Correspondence of Charles Darwin, vol. 22