More Letters of Charles Darwin — Volume 1. Darwin Charles

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СКАЧАТЬ (excluding thallogens and acrogens) that the genera include each 10.46 species (how near by chance to the Curculionidae), and I find 21 orders including single genera, and these 21 genera have on average 7.95 species; but if Lindley is right that Erythroxylon (with its 75 species) ought to be amongst the Malpighiads, then the average would be only 4.6 per genus.

      But here comes, as it appears to me, an odd thing (I hope I shall not quite weary you out). There are 29 other orders, each with 2 genera, and these 58 genera have on an average 15.07 species: this great number being owing to the 10 genera in the Smilaceae, Salicaceae (with 220 species), Begoniaceae, Balsaminaceae, Grossulariaceae, without which the remaining 48 genera have on an average only 5.91 species.

      This case of the orders with only 2 genera, the genera notwithstanding having 15.07 species each, seems to me very perplexing and upsets, almost, the conclusion deducible from the orders with single genera.

      I have gone higher, and tested the alliances with 1, 2, and 3 orders; and in these cases I find both the genera few in each alliance, and the species, less than the average of the whole kingdom, in each genus.

      All this has amused me, but I daresay you will have a good sneer at me, and tell me to stick to my barnacles. By the way, you agree with me that sometimes one gets despondent — for instance, when theory and facts will not harmonise; but what appears to me even worse, and makes me despair, is, when I see from the same great class of facts, men like Barrande deduce conclusions, such as his "Colonies" (41/3. Lyell briefly refers to Barrande's Bohemian work in a letter (August 31st, 1856) to Fleming ("Life of Sir Charles Lyell," II., page 225): "He explained to me on the spot his remarkable discovery of a 'colony' of Upper Silurian fossils, 3,400 feet deep, in the midst of the Lower Silurian group. This has made a great noise, but I think I can explain away the supposed anomaly by, etc." (See Letter 40, Note.) and his agreement with E. de Beaumont's lines of Elevation, or such men as Forbes with his Polarity (41/4. Edward Forbes "On the Manifestation of Polarity in the Distribution of Organised Beings in Time" ("Edinburgh New Phil. Journal," Volume LVII., 1854, page 332). The author points out that "the maximum development of generic types during the Palaeozoic period was during its earlier epochs; that during the Neozoic period towards its later periods." Thus the two periods of activity are conceived to be at the two opposite poles of a sphere which in some way represents for him the system of Nature.); I have not a doubt that before many months are over I shall be longing for the most dishonest species as being more honest than the honestest theories. One remark more. If you feel any interest, or can get any one else to feel any interest on the aberrant genera question, I should think the most interesting way would be to take aberrant genera in any great natural family, and test the average number of species to the genera in that family.

      How I wish we lived near each other! I should so like a talk with you on geographical distribution, taken in its greatest features. I have been trying from land productions to take a very general view of the world, and I should so like to see how far it agrees with plants.

      LETTER 42. TO MRS. LYELL.

      (42/1. Mrs. Lyell is a daughter of the late Mr. Leonard Horner, and widow of Lieut. — Col. Lyell, a brother of Sir Charles.)

      Down, January 26th {1856}.

      I shall be very glad to be of any sort of use to you in regard to the beetles. But first let me thank you for your kind note and offer of specimens to my children. My boys are all butterfly hunters; and all young and ardent lepidopterists despise, from the bottom of their souls, coleopterists.

      The simplest plan for your end and for the good of entomology, I should think, would be to offer the collection to Dr. J.E. Gray for the British Museum on condition that a perfect set was made out for you. If the collection was at all valuable, I should think he would be very glad to have this done. Whether any third set would be worth making out would depend on the value of the collection. I do not suppose that you expect the insects to be named, for that would be a most serious labour. If you do not approve of this scheme, I should think it very likely that Mr. Waterhouse would think it worth his while to set a series for you, retaining duplicates for himself; but I say this only on a venture. You might trust Mr. Waterhouse implicitly, which I fear, as {illegible} goes, is more than can be said for all entomologists. I presume, if you thought of either scheme, Sir Charles Lyell could easily see the gentlemen and arrange it; but, if not, I could do so when next I come to town, which, however, will not be for three or four weeks.

      With respect to giving your children a taste for Natural History, I will venture one remark — viz., that giving them specimens in my opinion would tend to destroy such taste. Youngsters must be themselves collectors to acquire a taste; and if I had a collection of English lepidoptera, I would be systematically most miserly, and not give my boys half a dozen butterflies in the year. Your eldest has the brow of an observer, if there be the least truth in phrenology. We are all better, but we have been of late a poor household.

      LETTER 43. TO J.D. HOOKER. Down {1855}.

      I should have less scruple in troubling you if I had any confidence what my work would turn out. Sometimes I think it will be good, at other times I really feel as much ashamed of myself as the author of the "Vestiges" ought to be of himself. I know well that your kindness and friendship would make you do a great deal for me, but that is no reason that I should be unreasonable. I cannot and ought not to forget that all your time is employed in work certain to be valuable. It is superfluous in me to say that I enjoy exceedingly writing to you, and that your answers are of the greatest possible service to me. I return with many thanks the proof on Aquilegia (43/1. This seems to refer to the discussion on the genus Aquilegia in Hooker and Thomson's "Flora Indica," 1855, Volume I., Systematic Part, page 44. The authors' conclusion is that "all the European and many of the Siberian forms generally recognised belong to one very variable species." With regard to cirripedes, Mr. Darwin spoke of "certain just perceptible differences which blend together and constitute varieties and not species" ("Life and Letters," I., page 379).): it has interested me much. It is exactly like my barnacles; but for my particular purpose, most unfortunately, both Kolreuter and Gartner have worked chiefly on A. vulgaris and canadensis and atro-purpurea, and these are just the species that you seem not to have studied. N.B. Why do you not let me buy the Indian Flora? You are too magnificent.

      Now for a short ride on my chief (at present) hobbyhorse, viz. aberrant genera. What you say under your remarks on Lepidodendron seems just the case that I want, to give some sort of evidence of what we both believe in, viz. how groups came to be anomalous or aberrant; and I think some sort of proof is required, for I do not believe very many naturalists would at all admit our view.

      Thank you for the caution on large anomalous genera first catching attention. I do not quite agree with your "grave objection to the whole process," which is "that if you multiply the anomalous species by 100, and divide the normal by the same, you will then reverse the names..." For, to take an example, Ornithorhynchus and Echidna would not be less aberrant if each had a dozen (I do not say 100, because we have no such cases in the animal kingdom) species instead of one. What would really make these two genera less anomalous would be the creation of many genera and sub-families round and radiating from them on all sides. Thus if Australia were destroyed, Didelphys in S. America would be wonderfully anomalous (this is your case with Proteaceae), whereas now there are so many genera and little sub-families of Marsupiata that the group cannot be called aberrant or anomalous. Sagitta (and the earwig) is one of the most anomalous animals in the world, and not a bit the less because there are a dozen species. Now, my point (which, I think is a slightly new point of view) is, if it is extinction which has made the genus anomalous, as a general rule the same causes of extinction would allow the existence of only a few species in such genera. Whenever we meet (which will be on the 23rd {at the} Club) I shall much like to hear whether this strikes you as sound. I feel all the time on the borders of a circle of truism. Of course I could not think of such a request, but you might possibly: — if Bentham does not think the whole subject rubbish, СКАЧАТЬ