From H. C. Watson   [after 24 July 1861]1

P.S. As to Veronica humifusa & Serpyllifolia.— Some botanists hold the former a good species. And the facts read either way.

V. humifusa perishes under given cir˜ces where V. Serpyllifolia flourishes, & naturally occurs under difft. cir˜ces.

Therefore it is a species of itself.— Or, therefore a vary. has a different climatal adaptation— Or, therefore a vary. is caused by difference of climate & soil acting on a succession of generations.2

CD annotations

Bottom of page: ‘Ch 7.’3 brown crayon
The date is suggested by the relationship between the contents of the postscript and topics discussed by George Maw in Maw 1861a (see n. 2, below). CD and Watson had been corresponding about the commingling of varieties and their possible divergence into new species. See the letter from H. C. Watson, 24 July 1861 and letter to H. C. Watson, [17 July 1861].
The genus Veronica was cited by Maw as an instance in which species and varieties co-exist in the same geographic locality, seemingly without the ‘mutually extirpating struggle upon which Mr. Darwin’s theory of progression so much depends.’ (Maw 1861a, p. 7600). In CD’s copy of Maw’s review (Darwin Pamphlet Collection–CUL), this passage is marked, and CD wrote next to it in pencil: ‘This shows that no advantage’.
The reference is to chapter seven, entitled ‘Laws of variation: varieties and species compared’, of CD’s ‘big book’ on species (Natural selection).

Please cite as “DCP-LETT-13853,” in Ɛpsilon: The Charles Darwin Collection accessed on 5 June 2025, https://epsilon.ac.uk/view/dcp-data/letters/DCP-LETT-13853