Dear Sir

Your very obliging note to me on a former occasion & your present of your Souvenirs (every word of which I have read with much interest) makes me think that perhaps you would oblige me this once with a little information.² I am slowly preparing a work on the variation of Species, & a statement by M. Flourens has interested me greatly, namely that the hybrid offspring of Dogs, wolves, & Jackalls are sterile inter se in the 3^d. generation. This is stated in his “Longévité Humaine”; but no details of his experiments are given.—³ Now I want to know whether details are published in any other work, or if not, (if you are at all intimate with M. Flourens)⁴ whether you would inquire for me, whether the sterility of these hybrids in the 3^d generation was ascertained in several cases, & whether they were sterile with the pure species, or only sterile one hybrid with another.— One more favour, M. Dureau de la Malle has published a pamphlet “sur les races des Chevaux,” which I have ordered, & am answered that it is not for sale.⁵ Could you find out for me whether it was published in any Transactions, & if not do you think you could procure me a copy.— I am well aware that it is mere chance whether you can so far oblige me, & could spare the time to take so much trouble.

With many apologies & with much respect, I remain | Dear Sir | Yours very faithfully | Ch. Darwin

I do not know whether you read English fluently, but if you do, I should be proud to send you a Copy of my “Journal of Researches into the Natural History of the countries visited by the Beagle”: parts of which, I think, might interest you; though having no pretension to compete in popularity with your Souvenirs.—⁶