More Letters of Charles Darwin Volume I [259]
blow, and do not know what to think. Of late several facts have turned up leading me to believe more firmly that the Glacial period did affect the equatorial regions; but I can make no answer to your argument, and am completely in a cleft stick. By an odd chance I have only a few days ago been discussing this subject, in relation to plants, with Dr. Hooker, who believes to a certain extent, but strongly urged the little apparent extinction in the equatorial regions. I stated in a letter some days ago to him that the tropics of S. America seem to have suffered less than the Old World. There are many perplexing points; temperate plants seem to have migrated far more than animals. Possibly species may have been formed more rapidly within tropics than one would have expected. I freely confess that you have confounded me; but I cannot yet give up my belief that the Glacial period did to certain extent affect the tropics.
LETTER 354. TO J.D. HOOKER. Down, February 25th [1862].
I have almost finished your Arctic paper, and I must tell you how I admire it. (354/1. "Outlines of the Distribution of Arctic Plants" [Read June 21st, 1860], "Linn. Soc. Trans." XXIII., 1862, page 251. The author's remarks on Mr. Darwin's theories of Geographical Distribution are given at page 255: they are written in a characteristically generous spirit.) The subject, treated as you have treated it, is really magnificent. Good Heaven, what labour it must have cost you! And what a grand prospect there is for the future. I need not say how much pleased I am at your notice of my work; for you know that I regard your opinion more than that of all others. Such papers are the real engine to compel people to reflect on modification of species; any one with an enquiring mind could hardly fail to wish to consider the whole subject after reading your paper. By Jove! you will be driven, nolens volens, to a cooled globe. Think of your own case of Abyssinia and Fernando Po, and South Africa, and of your Lebanon case (354/2. See "Origin," Edition VI., page 337.); grant that there are highlands to favour migration, but surely the lowlands must have been somewhat cooled. What a splendid new and original evidence and case is that of Greenland: I cannot see how, even by granting bridges of continuous land, one can understand the existing flora. I should think from the state of Scotland and America, and from isothermals, that during the coldest part of Glacial period, Greenland must have been quite depopulated. Like a dog to his vomit, I cannot help going back and leaning to accidental means of transport by ice and currents. How curious also is the case of Iceland. What a splendid paper you have made of the subject. When we meet I must ask you how much you attribute richness of flora of Lapland to mere climate; it seems to me very marvellous that this point should have been a sort of focus of radiation; if, however, it is unnaturally rich, i.e. contains more species than it ought to do for its latitude, in comparison with the other Arctic regions, would it not thus falsely seem a focus of radiation? But I shall hereafter have to go over and over again your paper; at present I am quite muddy on the subject. How very odd, on any view, the relation of Greenland to the mountains of E. N. America; this looks as if there had been wholesale extinction in E. N. America. But I must not run on. By the way, I find Link in 1820 speculated on relation of Alpine and Arctic plants being due to former colder climate, which he attributed to higher mountains cutting off the warm southern winds.
LETTER 355. J.D. HOOKER TO CHARLES DARWIN. Kew, November 2nd, 1862.
Did I tell you how deeply pleased I was with Gray's notice of my Arctic essay? (355/1. "American Journal of Science and Arts," XXXIV., and in Gray's "Scientific Papers," Volume I., page 122.) It was awfully good of him, for I am sure he must have seen several blunders. He tells me that Dr. Dawson (355/2. A letter (No. 144) by Sir J.D. Hooker, dated November 7th, 1862, on this subject
LETTER 354. TO J.D. HOOKER. Down, February 25th [1862].
I have almost finished your Arctic paper, and I must tell you how I admire it. (354/1. "Outlines of the Distribution of Arctic Plants" [Read June 21st, 1860], "Linn. Soc. Trans." XXIII., 1862, page 251. The author's remarks on Mr. Darwin's theories of Geographical Distribution are given at page 255: they are written in a characteristically generous spirit.) The subject, treated as you have treated it, is really magnificent. Good Heaven, what labour it must have cost you! And what a grand prospect there is for the future. I need not say how much pleased I am at your notice of my work; for you know that I regard your opinion more than that of all others. Such papers are the real engine to compel people to reflect on modification of species; any one with an enquiring mind could hardly fail to wish to consider the whole subject after reading your paper. By Jove! you will be driven, nolens volens, to a cooled globe. Think of your own case of Abyssinia and Fernando Po, and South Africa, and of your Lebanon case (354/2. See "Origin," Edition VI., page 337.); grant that there are highlands to favour migration, but surely the lowlands must have been somewhat cooled. What a splendid new and original evidence and case is that of Greenland: I cannot see how, even by granting bridges of continuous land, one can understand the existing flora. I should think from the state of Scotland and America, and from isothermals, that during the coldest part of Glacial period, Greenland must have been quite depopulated. Like a dog to his vomit, I cannot help going back and leaning to accidental means of transport by ice and currents. How curious also is the case of Iceland. What a splendid paper you have made of the subject. When we meet I must ask you how much you attribute richness of flora of Lapland to mere climate; it seems to me very marvellous that this point should have been a sort of focus of radiation; if, however, it is unnaturally rich, i.e. contains more species than it ought to do for its latitude, in comparison with the other Arctic regions, would it not thus falsely seem a focus of radiation? But I shall hereafter have to go over and over again your paper; at present I am quite muddy on the subject. How very odd, on any view, the relation of Greenland to the mountains of E. N. America; this looks as if there had been wholesale extinction in E. N. America. But I must not run on. By the way, I find Link in 1820 speculated on relation of Alpine and Arctic plants being due to former colder climate, which he attributed to higher mountains cutting off the warm southern winds.
LETTER 355. J.D. HOOKER TO CHARLES DARWIN. Kew, November 2nd, 1862.
Did I tell you how deeply pleased I was with Gray's notice of my Arctic essay? (355/1. "American Journal of Science and Arts," XXXIV., and in Gray's "Scientific Papers," Volume I., page 122.) It was awfully good of him, for I am sure he must have seen several blunders. He tells me that Dr. Dawson (355/2. A letter (No. 144) by Sir J.D. Hooker, dated November 7th, 1862, on this subject