From Thomas Rivers [3 February 1863]
You should live near a large nursery & your mind would find abundance of food.
when I first read the “Origin” I was amused at what I had observed with regard to “selection”.1 A patch of seedling trees if not transplanted seems to illustrate this (but perhaps I am taking a wrong view) the first year they are all equal in two or three years several will have pushed up—not confined to the outside of the patch which is easily accounted for by their finding more food— at the end of five or six years one or two or three will have smothered nearly all their brethren & then one alone will often be left. I have observed in what we call “pans” (flat pots of seedling) of pines which have stood a few years in one place forgotten the first year all equal the second & third a few more adventurous have made roots through the holes at the bottom & at last one gigantic fellow spreads over all & the underlings die.
His observations of "selection" in growth of seedling trees.
Please cite as
Darwin Correspondence Project, “Letter no. 3965,” accessed on 28 September 2016, http://www.darwinproject.ac.uk/DCP-LETT-3965