Seeks the assistance of a professional chemist in securing a qualitative analysis of the fluid secreted by the glands of Drosera which have the power of dissolving animal matter out of the bodies of insects. [See 8979.]
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The Charles Darwin Collection
The Darwin Correspondence Project is publishing letters written by and to the naturalist Charles Darwin (1809–1882). Complete transcripts of letters are being made available through the Project’s website (www.darwinproject.ac.uk) after publication in the ongoing print edition of The Correspondence of Charles Darwin (Cambridge University Press 1985–). Metadata and summaries of all known letters (c. 15,000) appear in Ɛpsilon, and the full texts of available letters can also be searched, with links to the full texts.
Seeks the assistance of a professional chemist in securing a qualitative analysis of the fluid secreted by the glands of Drosera which have the power of dissolving animal matter out of the bodies of insects. [See 8979.]
Thanks EF for his offer of assistance. Could the viscid secretions [in glands of Drosera] contain pepsin? Will the sodium carbonate render the testing of organic matter difficult? [See 8979.] Will send the fluid in a fortnight.
Agrees to delay sending the fluid [from the glands of Drosera] until early October. Will try suggestion about pepsin. [See 8981.]
Although CD’s experiments with pepsin were unsuccessful, he observed that the glands [of Drosera] as far as acid is concerned act just as the stomach of a mammal. Further experiments detailed. The secretion must contain something analogous to pepsin. [See 9062.]
Will follow EF’s suggestions as to securing purity of fibrin.
Is sending washings of 445 leaves in EF’s distilled water with 20 grains of carbonate of soda. Details of the difficulties and complications involved.
Requests a piece of the most sensitive litmus paper in order to test the secretions of minute hairs of plants which catch minute flies. [See 9098.]
Finds the negative information sent by EF of great interest [see 9094].
More on his own experiments and the perplexing results when using the sensitive litmus paper.
Apologises for his ignorance in interpreting the results secured in his testing with blue litmus paper.
Requests permission to call upon EF either Friday or Saturday morning [14 or 15 November].
Sends sodium carbonate for Drosera experiments. Will try to determine what the solvent is.
Is going to Switzerland, so analysis of Drosera washings will be delayed. Agrees with CD that solvent is probably pepsin.
CD’s discovery of acidity of Drosera secretion is interesting. EF explains how hydrochloric acid can be detected and identified. [See Insectivorous plants, p. 88.]
Has sent CD some pure distilled water for his Drosera experiments.
The results of EF’s tests for acids in the secretion of Drosera are largely negative [see Insectivorous plants, p. 88].
Sends some litmus paper for CD.