Man purchases the individual animals or plants which seem to him the best in any respect--some more so, and some less so--and, without any matching or pairing, the breed in the course of time is surely altered.

The absence in numerous instances of intermediate or blending forms, in the border country between two closely allied geographical races or close species, seemed to me a greater difficulty when I discussed the subject in the "Origin." With respect to your illustration, it formerly drove me half mad to attempt to account for the increase or diminution of the productiveness of an organism; but I cannot call to mind where my difficulty lay.
(279/2.

See Letters 209-16.) Natural Selection always applies, as I think, to each individual and its offspring, such as its seeds, eggs, which are formed by the mother, and which are protected in various ways.
(279/3.

It was in regard to this point that Romanes had sent the MS.

to Darwin.