I have often speculated on antiquity of islands, but not with your precision, or at all under the point of view of Natural Selection NOThaving done what might have been anticipated. The argument of littoral Miocene shells at the Canary Islands is new to me. I was deeply impressed (from the amount of the denudation) [with the] antiquity of St. Helena, and its age agrees with the peculiarity of the flora. With respect to bats at New Zealand (N.B. There are two or three European bats in Madeira, and Ithink in the Canary Islands) not having given rise to a group of non-volant bats, it is, now you put the case, surprising; more especially as the genus of bats in New Zealand is very peculiar, and therefore has probably been long introduced, and they now speak of Cretacean fossils there. But the first necessary step has to be shown, namely, of a bat taking to feed on the ground, or anyhow, and anywhere, except in the air. I am bound to confess I do know one single such fact, viz. of an Indian species killing frogs. Observe, that in my wretched Polar Bear case, I do show the first step by which conversion into a whale "would be easy," "would offer no difficulty"!! So with seals, I know of no fact showing any the least incipient variation of seals feeding on the shore. Moreover, seals wander much; I searched in vain, and could not find ONE case of any species of seal confined to any islands. And hence wanderers would be apt to cross with individuals undergoing any change on an island, as in the case of land birds of Madeira and Bermuda. The same remark applies even to bats, as they frequently come to Bermuda from the mainland, though about 600 miles distant. With respect to the Amblyrhynchus of the Galapagos, one may infer as probable, from marine habits being so rare with Saurians, and from the terrestrial species being confined to a few central islets, that its progenitor first arrived at the Galapagos; from what country it is impossible to say, as its affinity I believe is not very clear to any known species. The offspring of the terrestrial species was probably rendered marine. Now in this case I do not pretend I can show variation in habits;but we have in the terrestrial species a vegetable feeder (in itself a rather unusual circumstance), largely on LICHENS, and it would not be a great change for its offspring to feed first on littoral algae and then on submarine algae. I have said what I can in defence, but yours is a good line of attack. We should, however, always remember that no change will ever be effected till a variation in the habits or structure or of both CHANCE to occur in the right direction, so as to give the organism in question an advantage over other already established occupants of land or water, and this may be in any particular case indefinitely long. I am very glad you will read my dogs MS., for it will be important to me to see what you think of the balance of evidence. After long pondering on a subject it is often hard to judge. With hearty thanks for your most interesting letter. Farewell.
My dear old master, C. DARWIN.
CHARLES DARWIN TO J.D. HOOKER.
Down, September 2nd [1860].
My dear Hooker, I am astounded at your news received this morning. I am become such an old fogy that I am amazed at your spirit. For God's sake do not go and get your throat cut. Bless my soul, I think you must be a little insane. Imust confess it will be a most interesting tour; and, if you get to the top of Lebanon, I suppose extremely interesting--you ought to collect any beetles under stones there; but the Entomologists are such slow coaches. Idare say no result could be made out of them. [They] have never worked the Alpines of Britain.
If you come across any Brine lakes, do attend to their minute flora and fauna; I have often been surprised how little this has been attended to.
I have had a long letter from Lyell, who starts ingenious difficulties opposed to Natural Selection, because it has not done more than it has.
This is very good, as it shows that he has thoroughly mastered the subject;and shows he is in earnest. Very striking letter altogether and it rejoices the cockles of my heart.
...How I shall miss you, my best and kindest of friends. God bless you.
Yours ever affectionately, C. DARWIN.
CHARLES DARWIN TO ASA GRAY.
Down, September 10 [1860].
...You will be weary of my praise, but it (Dr. Gray in the 'Atlantic Monthly' for July, 1860.) does strike me as quite admirably argued, and so well and pleasantly written. Your many metaphors are inimitably good. Isaid in a former letter that you were a lawyer, but I made a gross mistake, I am sure that you are a poet. No, by Jove, I will tell you what you are, a hybrid, a complex cross of lawyer, poet, naturalist and theologian! Was there ever such a monster seen before?
I have just looked through the passages which I have marked as appearing to me extra good, but I see that they are too numerous to specify, and this is no exaggeration. My eye just alights on the happy comparison of the colours of the prism and our artificial groups. I see one little error of fossil CATTLE in South America.
It is curious how each one, I suppose, weighs arguments in a different balance: embryology is to me by far the strongest single class of facts in favour of change of forms, and not one, I think, of my reviewers has alluded to this. Variation not coming on at a very early age, and being inherited at not a very early corresponding period, explains, as it seems to me, the grandest of all facts in natural history, or rather in zoology, viz. the resemblance of embryos.
[Dr. Gray wrote three articles in the 'Atlantic Monthly' for July, August, and October, which were reprinted as a pamphlet in 1861, and now form chapter iii. in 'Darwiniana' (1876), with the heading 'Natural Selection not inconsistent with Natural Theology.']
CHARLES DARWIN TO C. LYELL
Down, September 12th [1860].