I received this morning your "Unite de l'Espece Humaine" [published in 1861], and most sincerely do I thank you for this your very kind present. I had heard of and been recommended to read your articles, but, not knowing that they were separately published, did not know how to get them. So your present is most acceptable, and I am very anxious to see your views on the whole subject of species and variation; and I am certain to derive much benefit from your work. In cutting the pages I observe that you have most kindly mentioned my work several times. My views spread slowly in England and America; and I am much surprised to find them most commonly accepted by geologists, next by botanists, and least by zoologists. I am much pleased that the younger and middle-aged geologists are coming round, for the arguments from Geology have always seemed strongest against me. Not one of the older geologists (except Lyell) has been even shaken in his views of the eternal immutability of species. But so many of the younger men are turning round with zeal that I look to the future with some confidence. I am now at work on "Variation under Domestication," but make slow progress-- it is such tedious work comparing skeletons.

With very sincere thanks for the kind sympathy which you have always shown me, and with much respect,...

P.S.--I have lately read M. Naudin's paper (126/1. Naudin's paper ("Revue Horticole," 1852) is mentioned in the "Historical Sketch" prefixed to the later editions of the "Origin" (Edition VI., page xix). Naudin insisted that species are formed in a manner analogous to the production of varieties by cultivators, i.e., by selection, "but he does not show how selection acts under nature." In the "Life and Letters," II., page 246, Darwin, speaking of Naudin's work, says: "Decaisne seems to think he gives my whole theory."), but it does not seem to me to anticipate me, as he does not show how selection could be applied under nature; but an obscure writer (126/2. The obscure writer is Patrick Matthew (see the "Historical Sketch" in the "Origin.") on forest trees, in 1830, in Scotland, most expressly and clearly anticipated my views--though he put the case so briefly that no single person ever noticed the scattered passages in his book.

(127/1. The following letter was in reply to one from Mr. Hindmarsh, to whom Mr. Darwin had written asking for information on the average number of animals killed each year in the Chillingham herd. The object of the request was to obtain information which might throw light on the rate of increase of the cattle relatively to those on the pampas of South America. Mr. Hindmarsh had contributed a paper "On the Wild Cattle of Chillingham Park" to the "Annals and Mag. Nat. Hist." Volume II., page 274, 1839.)

I thank you sincerely for your prompt and great kindness, and return the letter, which I have been very glad to see and have had copied. The increase is more rapid than I anticipated, but it seems rather conjectural; I had hoped that in so interesting a case some exact record had been kept. The number of births, or of calves reared till they followed their mothers, would perhaps have been the best datum. From Mr. Hardy's letter I infer that ten must be annually born to make up the deaths from various causes. In Paraguay, Azara states that in a herd of 4,000, from 1,000 to 1,300 are reared; but then, though they do not kill calves, but castrate the young bulls, no doubt the oxen would be killed earlier than the cows, so that the herd would contain probably more of the female sex than the herd at Chillingham. There is not apparently any record whether more young bulls are killed than cows. I am surprised that Lord Tankerville does not have an exact record kept of deaths and sexes and births: after a dozen years it would be an interesting statistical record to the naturalist and agriculturist.

(128/1. The death of Professor Henslow (who was Sir J.D. Hooker's father- in-law) occurred on May 16th, 1861.)

Thanks for your two notes. I am glad that the burial is over, and sincerely sympathise and can most fully understand your feelings at your loss.

I grieve to think how little I saw of Henslow for many years. With respect to a biography of Henslow, I cannot help feeling rather doubtful, on the principle that a biography could not do him justice. His letters were generally written in a hurry, and I fear he did not keep any journal or diary. If there were any vivid materials to describe his life as parish priest, and manner of managing the poor, it would be very good.