Asks JP to remember him if anything occurs to him "in regard to inheritance at corresponding or rather earlier ages". Sends JP a few examples for his "Chronometry of life". CD is sure he often met with striking facts but he disregarded them. "Deviations alone would have struck me."
Effects of different climates on breeding periods.
Down Bromley Kent
I am heartily obliged for your present, but hardly feel worthy of it. I was so very much interested by many things which you told me, that you may be sure I shall read your Lectures; but I shall not be able very soon, as I have several big borrowed books, which must be returned soon. Will you be so very kind as to remember me, if anything occurs to you, in regard to inheritance at corresponding or rather earlier ages; & in regard to constitution & complexion.—
I wish I could give you any facts on your Chronometry of Life; I am sure I have often met with striking facts; but I have disregarded such facts & deviations alone would have struck me.
You know of course that the same bird in state of nature further S. or N. lays eggs at different times; & not rarely 2 broods in the S. & only one in N. The degree to which they sit, varies under different temperatures; but I do not mean by this that eggs hatch at different periods.— Some Batrachians of same species are oviparous or ovoviviparous under different climates. The periodical shedding of wool in sheep is no doubt affected by tropical climate. The appearance of second teeth has been greatly affected & accelerated in our domestic quadrupeds. Certain breeds of fowls, acquire their perfect plumage slower than others, so that after the down they are apt to be almost naked.
I see Youatt does not seem to doubt that period of breeding has been accelerated with the general early maturity of our improved cattle. Tessier gives 321 days as longest period & 240 as shortest period of gestation in cattle.
I do not suppose these rough remarks will be of any interest to you, but I send them for mere chance
Pray believe me, with very many thanks | Yours sincerely | Ch. Darwin
Cocks can be distinguished from Hens, earlier in some breeds than others.
- f1 5314.f1The year is established by the relationship between this letter and the letter to James Paget, [15 October -- 19 November 1859] (Correspondence vol. 7).
- f2 5314.f2It is not known what present Paget had given CD. The discussion that CD refers to may have taken place at the 16 December 1858 meeting of the Philosophical Club of the Royal Society of London, which CD and Paget both attended (see Royal Society, Philosophical Club minutes). The `Lectures' were probably Paget's Lectures on surgical pathology (Paget 1853). There is a heavily annotated copy of the first volume of Paget 1853 in the Darwin Library--CUL (see Marginalia 1: 658--61); it is not inscribed, so it is unlikely to have been the `present' that CD refers to. Volume 1 of the two-volume work dealt with hypertrophy, atrophy, repair, inflammation, mortification, and specific diseases; volume 2 dealt with tumours. CD read the first three chapters and the last chapter of the first volume in early 1859 (see CD's reading notebooks (Correspondence vol. 4, Appendix IV, 128: 24), and his annotations in the back of the volume at CUL).
- f3 5314.f3See Correspondence vol. 7, letter to James Paget, [15 October -- 19 November 1859].
- f4 5314.f4Paget delivered his lecture `On the chronometry of life' (Paget 1859) at the Royal Institution of Great Britain on 8 April 1859. The lecture was intended `to illustrate the law that the processes of organic life are regulated with a regard to time, as exact as that which is observed by them in respect of size and weight and quantity of material employed in them' (Paget 1859, p. 117).
- f5 5314.f5A heavily annotated copy of William Youatt's Cattle: their breeds, management, and diseases (Youatt 1834) is in the Darwin Library--CUL (see Marginalia 1: 885--8). Youatt discusses `The proper age for breeding' in Youatt 1834, pp. 526--7; see also Variation 1: 87.
- f6 5314.f6CD probably refers to the note in Youatt 1834, p. 527, which mentions the observations of Alexandre Henri Tessier. He also cited the note in Variation 1: 87 and n. 58.