My dear Gray

I have a multitude of things to thank you for; & hardly know how to begin. I forward & stamped letter to Grisebach in yours of Sept. 2^d.² Always use me this way, when convenient; as a scrap from you, I consider very good payment. With respect to Von Baer’s statement about Guinea-pig; I sh^d. much like to know where it is;³ but it can hardly be trusted unless he has brought forward some quite new evidence with respect to the unknown wild type of Guinea-pig. I have seen some of the Hybrids of Rabbit & Hare;⁴ & believe case is to be trusted; but I do not know that the exact half-bloods are perfectly fertile inter se: it is a particularly curious case, because many have perseverinly tried & utterly failed even to unite these 2 species.

Your letter of the 2^d. was very pleasant, & so was that to Hooker, (just received from Lady Hooker)⁵ which made us all (ie my family) laugh heartily. I have received the Dialogue from Silliman’s October no^r.⁶ Also the Proofs of the 3^d. Atlantic Article.⁷ These both seem to me very good; but if forced to choose, I think I sh^d pick out the 2^d article as best.— (I don’t know though)    I do not pretend to be a good judge, as I have never attended to Logic, Philosophy &c; but it is my opinion that you are best reasoner, of any man, let him who he may, that I ever read. As for your metaphors & similes, they make me envious: I sh^d like to steal a few: yet you never are tempted to use them prodigally. The two last essays are far the best Theistic essays I ever read. But I must return to the metaphors— I like specially that of the woman & the cloth;⁸ and that of the rain-drops on the ocean.—⁹ I believe my chief difference with you, is that I (unfortunately) think more of the rain-drops on the ocean than on those on the land. All your arguments about Design seem to me excellent; but I must hereafter read all again. I have a feeling that the existence of the multitude of Stars & the motion of the planetary system &c are equally good with living beings to prove a First Cause; & yet if there were no living things, there could hardly be design.— But I well know that I am muddled-headed on this subject.—

I have sent the August no^r of Atlantic to Annals & Mag. of N. History; & offered to pay for its printing, if its length prevented its insertion: I have affixed your name, as Lyell agreed that it so greatly added to its value:¹⁰ I do most sincerely hope that I have not done wrong. The Saturday Review has lately been discussing Design; so I will send the Dialogue to it, of course without your name; whether they will print, I doubt.—¹¹ I wish I could think of any Journal to print the October number.—¹²

I have had a letter of 14 folio pages from Harvey against my Book, with some ingenious & new remarks; but it is an extraordinary fact that he does not understand at all what I mean by Nat. Selection.¹³ I have begged him to read the Dialogue in next Silliman, as you never touch the subject without making it clearer.¹⁴ I look at it as even more extraordinary that you never say a word or use an epithet which does not express fully my meaning. Now Lyell, Hooker & others, who perfectly understand my book, yet sometimes use expressions to which I demur. If I had to write my book again I would use “Natural Preservation” & drop “Selection”, but it is too late now. D^r. Gray of B. Museum says to me “it is, you know, obviously impossible that there can be any Selection in case of Plants”.¹⁵ I made no answer; for it is hopeless. Well, your extraordinary labour is over; if there is any fair amount of truth in my views, I am well assured that your great labour has not been thrown away. I am perfectly convinced that had it not been for yourself, Hooker, Huxley & Lyell; my Book would Scientifically have been a complete failure. You have been most generous & disinterested in your exertions; & I thank you from my heart.

Farewell, my dear Gray | Yours most truly | C. Darwin

P.S. Please observe that if the Appletons lose by the 2^d Edition never selling, I sh^d. prefer repaying the money they have paid me.—¹⁶

I am writing this at Eastbourne, where we have come to sea-side for my girls health, & she has certainly profited by it.—   Consequently I shall not see Clark (Agassiz’s man).¹⁷

I have been infinitely amused by working at Drosera: the movements are really curious; & the manner in which the leaves detect certain nitrogenous compounds is marvellous.—   You will laugh; but it is at present, my full belief (after endless experiment) that they detect (& move in consequence of) the $\frac{1}{2880}$ part of a single grain of Nitrate of Ammonia; but the Muriate & Sulphate of Ammonia bother their chemical skill, & they cannot make anything of the nitrogen in these salts!¹⁸

I began this work on Drosera in relation to gradation as throwing light on Dionæa.—¹⁹

Does Spiranthes (or any odd genus of Orchids) grow near you; if so, I would ask you next summer to make a few observations, which would not take 10 minutes for me. There is very curious contrivance in our S. autumnalis for insect fertilisation; viz a decked boat-full of viscid matter & on a touch the deck splits & leaves viscid matter exposed. But I would explain if you have a Spiranthes.—

I yet hope, & almost believe, that the time will come when you will go further in believing a very large amnt of modification of species, than you did at first or do now. Can you tell me whether you believe further or more firmly than you did at first? I sh^d really like to know this. I can perceive in my immense correspondence with Lyell, who objected to much at first, that he has, perhaps unconsciously to himself converted himself very much during last six months.— & I think this is case even with Hooker.—   This fact gives me far more confidence than any other fact.—

P.S. 2^d | How does Dana get on? I wrote to him, a month or two ago.—²⁰