To Mary Treat 5 January 1872
Down, | Beckenham, Kent.
Jan 5. 1872
Your observations & experiments on the sexes of butterflies are by far the best, as far as known to me, which have ever been made.1 They seem to me so important, that I earnestly hope you will repeat them & record the exact numbers of the larvæ which you tempt to continue feeding & deprive of food, & record the sexes of the mature insect.
Assuredly you ought then to publish the result in some well-known scientific journal.2 I am glad to hear that your observations on Drosera will be published.3
I have attended to this subject during several years, & have almost M.S enough to make a volume; but have never yet found time to publish it.
I am very much obliged for yr courteous letter & remain dear Madam | yours faithfully | Charles Darwin
Praises MT’s observations and asks her to repeat experiments on the the relation of sexes of butterflies to the nutrition of the larvae.
Is glad she will publish her observations on Drosera.