P.S.--I do not know how far you will care to hear, but I find Moquin-Tandon treats in his 'Teratologie' on villosity of plants, and seems to attribute more to dryness than altitude; but seems to think that it must be admitted that mountain plants are villose, and that this villosity is only in part explained by De Candolle's remark that the dwarfed condition of mountain plants would condense the hairs, and so give them the APPEARANCE of being more hairy. He quotes Senebier, 'Physiologie Vegetale,' as authority--Isuppose the first authority, for mountain plants being hairy.
If I could show positively that the endemic species were more hairy in dry districts, then the case of the varieties becoming more hairy in dry ground would be a fact for me.
CHARLES DARWIN TO J.D. HOOKER.
Down, June 3rd [1857].
My dear Hooker, I am going to enjoy myself by having a prose on my own subjects to you, and this is a greater enjoyment to me than you will readily understand, as Ifor months together do not open my mouth on Natural History. Your letter is of great value to me, and staggers me in regard to my proposition. Idare say the absence of botanical facts may in part be accounted for by the difficulty of measuring slight variations. Indeed, after writing, this occurred to me; for I have Crucianella stylosa coming into flower, and the pistil ought to be very variable in length, and thinking of this I at once felt how could one judge whether it was variable in any high degree. How different, for instance, from the beak of a bird! But I am not satisfied with this explanation, and am staggered. Yet I think there is something in the law; I have had so many instances, as the following: I wrote to Wollaston to ask him to run through the Madeira Beetles and tell me whether any one presented anything very anomalous in relation to its allies. He gave me a unique case of an enormous head in a female, and then I found in his book, already stated, that the size of the head was ASTONISHINGLYvariable. Part of the difference with plants may be accounted for by many of my cases being secondary male or FEMALE characters, but then I have striking cases with hermaphrodite Cirripedes. The cases seem to me far too numerous for accidental coincidences, of great variability and abnormal development. I presume that you will not object to my putting a note saying that you had reflected over the case, and though one or two cases seemed to support, quite as many or more seemed wholly contradictory. This want of evidence is the more surprising to me, as generally I find any proposition more easily tested by observations in botanical works, which Ihave picked up, than in zoological works. I never dreamed that you had kept the subject at all before your mind. Altogether the case is one more of my MANY horrid puzzles. My observations, though on so infinitely a small scale, on the struggle for existence, begin to make me see a little clearer how the fight goes on. Out of sixteen kinds of seed sown on my meadow, fifteen have germinated, but now they are perishing at such a rate that I doubt whether more than one will flower. Here we have choking which has taken place likewise on a great scale, with plants not seedlings, in a bit of my lawn allowed to grow up. On the other hand, in a bit of ground, 2 by 3 feet, I have daily marked each seedling weed as it has appeared during March, April and May, and 357 have come up, and of these 277 have ALREADY been killed chiefly by slugs. By the way, at Moor Park, I saw rather a pretty case of the effects of animals on vegetation: there are enormous commons with clumps of old Scotch firs on the hills, and about eight or ten years ago some of these commons were enclosed, and all round the clumps nice young trees are springing up by the million, looking exactly as if planted, so many are of the same age. In other parts of the common, not yet enclosed, I looked for miles and not ONE young tree could be seen. I then went near (within quarter of a mile of the clumps) and looked closely in the heather, and there I found tens of thousands of young Scotch firs (thirty in one square yard) with their tops nibbled off by the few cattle which occasionally roam over these wretched heaths. One little tree, three inches high, by the rings appeared to be twenty-six years old, with a short stem about as thick as a stick of sealing-wax. What a wondrous problem it is, what a play of forces, determining the kind and proportion of each plant in a square yard of turf! It is to my mind truly wonderful. And yet we are pleased to wonder when some animal or plant becomes extinct.
I am so sorry that you will not be at the Club. I see Mrs. Hooker is going to Yarmouth; I trust that the health of your children is not the motive.
Good-bye.
My dear Hooker, ever yours, C. DARWIN.
P.S.--I believe you are afraid to send me a ripe Edwardsia pod, for fear Ishould float it from New Zealand to Chile!!!
CHARLES DARWIN TO J.D. HOOKER.
Down, June 5 [1857].
My dear Hooker, I honour your conscientious care about the medals. (The Royal Society's medals.) Thank God! I am only an amateur (but a much interested one) on the subject.
It is an old notion of mine that more good is done by giving medals to younger men in the early part of their career, than as a mere reward to men whose scientific career is nearly finished. Whether medals ever do any good is a question which does not concern us, as there the medals are. Iam almost inclined to think that I would rather lower the standard, and give medals to young workers than to old ones with no ESPECIAL claims.