To J. D. Hooker 3 June 1
Down Bromley Kent
My dear Hooker
I am going to enjoy myself by having a prose on my own subjects to you, & this is a greater enjoyment to me than you will readily understand; as I for months together do not open my mouth on Nat. History.— Your letter is of great value to me & staggers me in regard to my proposition. I daresay the absence of Bot. facts may in part be accounted for by the difficulty of measuring slight variations.2 Indeed after writing this occurred to me; for I have Crucianella stylosa coming into flower & the pistil ought to be very variable in length, & thinking of this I at once felt how could one judge whether it was variable in any high degree. How different, for instance, from Beak of Bird!— But I am not satisfied with this explanation, & am staggered. Yet I think there is something in law; I have had so many instances as following: I wrote to Wollaston to ask him to run through Madeira Beetles & tell me whether any one presented anything very anomalous in relation to its allies: he gave me a unique case of enormous head in female & then I found in his Book already stated that the size of head was astonishingly variable.—3 Part of 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.—4 The cases seem to me far too numerous for accidental coincidences of great variability & abnormal development. I presume you will not object to my putting a note saying that you had reflected over case & 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 Bot. works, which I have picked up, than in Zoological works.— I never dreamed that you had kept the subject at all before your mind.5 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 16 kinds of seed sown on my meadow, 15 have germinated, but now they are perishing at such a rate that I doubt whether more than one will flower.6 Here we have choking, which has taken place likewise on great scale with plant not seedlings in a bit of my lawn allowed to grow up. On other hand in a bit of ground 23 feet, I have daily marked each seedling weed as it has appeared during March, April & May, and 357 have come up, & of these 277 have already been killed chiefly by slugs.—7 By the way at Moor Park, I saw rather pretty case of effect of animals on vegetation: there are enormous commons with clumps of old Scotch firs on hills, & about 8–10 years ago some of these commons were enclosed & all round the clumps nice young trees are springing up by the millions, looking exactly as if planted so many are of same age. In other part of common, not yet enclosed, I looked for miles & not one young tree cd be seen; I then went near (within of mile of the clumps & looked closely in the heather, & there I found tens of thousands of young scotch-firs (30 in one square yard) with their tops nibbled off by the few cattle which occasionally roam over these wretched Heaths. One little tree 3 inches high, by the rings appeared to be 26 years old with a short stem about as thick as stick of sealing wax.— What a wondrous problem it is,—what a play of forces, determining the kinds & proportions 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.—8
I am so sorry that you will not be at Club. I see Mrs Hooker is going to Yarmouth; I trust that the health of your children is not motive.—
Good Bye | My dear Hooker | Ever yours | Ch. Darwin
P.S. | You must not forget sometime to let me have the Himalayan thistle case in short abstract.
I believe you are afraid to send me a ripe Edwardsia pod for fear I shd float it from N. Zealand to Chile!!!
"Law" [see 2092] correlating variability and abnormal development not confirmed by JDH for plants.
CD studies struggle for existence in his weed garden.
Scotch fir observed at Moor Park.
Please cite as
Darwin Correspondence Project, “Letter no. 2101,” accessed on 24 January 2017, http://www.darwinproject.ac.uk/DCP-LETT-2101