To Frederick Capes   23 November 1881

Dear Sir.

I thank you much for your letter which has interested me exceedingly—¹ I happen to have been working lately on the structure of Euphorbia peplus. and was thus led to wonder what could be the use of the Marvellous Milk ducts & milky fluid—² Indeed this is not known to any botanist, Now it seems to me not improbable that it serves merely as a protection,—as I believe to be the case with the various Alkaloids & essential oils in so many plants— I hope before long to get time to try some experiments on worms & whenever I publish on Euphorbia will quote your statements, with any remarks which I may be able to add,—

Again thanking you I remain— | Dear Sir. | Yours faithfully. | Ch. Darwin

PS. My gardener³ declares that he killed as a boy a wart on his hand with the milk of some Spurge or Euphorbia!—