Discusses checks on growth of species population; use of term "mutation" in his species theory. His belief in species mutability.
Down Bromley Kent
I have taken my leisure in thanking you for your last letter, & discussion, to me very interesting, on the increase of species. Since your letter, I have met with a very similar view in Richardson, who states that the young are driven away by the old into unfavourable districts, & then mostly perish.— When one meets with such unexpected statistical returns on the increase & decrease & proportions of deaths & births amongst mankind & in this well-known country of ours, one ought not to be in the least surprised at ones ignorance, when, where & how, the endless increase of our robins & sparrows is checked.—
Thanks for your hints about terms of “mutation” &c; I had
had some suspicions, that it was not quite correct, & yet I do not yet see my
way to arrive at any better terms: it will be years before I publish, so that I shall
have plenty of time to think of better words— Development
We are all well, wife & children three, & as flourishing as this horrid, house-confining, temper-souring weather permits.—
With thanks, believe me | Your's very sincerely | C. Darwin
- f1 828.f1J. Richardson 1829–37, 2: xix–xx. CD recorded this work as having been read on 29 January 1845 (DAR 119; Vorzimmer 1977, p. 133). It is in the Darwin Library–CUL. John Richardson referred to the practice of adult birds driving the young into less favourable breeding grounds but said nothing about the young perishing. For Jenyns' comments on this subject see Jenyns 1846, pp. 113–17.