Embryology of plants of low systematic order. Comparative development begins only with first post-cotyledonary leaves.
Curt letter to JDH from George Henslow.
Believes, with CD, that extinction may be an important factor in explaining plant distributions, but sees no reason why the several species of a genus must ever have had a common or continuous area. "Convince me of that, or show me any good grounds for it … and I think you would carry me a good way with you". It is just such people as AG that CD has to satisfy and convince.
Feels that the crossing of individuals is important in repressing variation and perhaps in perpetuating the species, but instances some plants in which it cannot, apparently, take place.
THH comments on G. A. Brullé’s paper ["Researches upon the transformations of the appendages of the Articulata", Ann. & Mag. Nat. Hist. 13 (1844): 484–6].
States he has "misgivings about the definiteness of species". Believes there is some inherent tendency for plants to originate varieties. Cross-fertilisation is likely in most cases but sees difficulties with plants like Adlumia.
Is looking forward to returning home [from Moor Park hydropathic establishment]. News of other patients and the books she is reading. Although feeling well, cannot walk much.
Gives CD further details of the fertility of the offspring from cross of a yak and Indian cow, the so-called chooboos, whose fertility he has traced to the seventh generation [see Natural selection, pp. 437–8].
Refers to CD’s letter of "May last". ARW’s views on order of succession of species are in accordance with CD’s.
Disappointed that his paper ["On the law which has regulated the introduction of new species", Ann. & Mag. Nat. Hist. 2d ser. 16 (1855): 184–96] elicited no discussion; now ARW is trying to prove it. Paper merely states the theory.
On black jaguars breeding inter se: ARW has never heard of a parti-coloured one.
No summary available.
Suggests CD use the common origin of the French "chef" and the English "head" or "évêque" and "bishop" to illustrate the parallels between extinction and transitional forms in language and palaeontology [see Natural selection, p. 384].
On classification and possibilities of a scientific morphology and zoology. CD’s "pedigree business" is important for physiology but has nothing to do with pure zoology any more than human pedigree has to do with the census. Zoological classification is a census of the animal world.
Discusses the difficulties of breeding mules by crossing canaries and finches.
Describes his work, which demonstrates that hybrids of Cactus are fertile.
Writes concerning library books requested by CD.
He was unaware that varieties occurred proportionately more in large genera.
Recommends a work [Leonard Gyllenhaal, Insecta Suecica, 4 vols. (1808–27)] for tabulating varieties.
Lists "close geographical representatives of Europaean species" based on the species numbers [in T. V. Wollaston, Catalogue of the coleopterous insects of Madeira (1857)].
Responds to CD’s article on kidney beans [Collected papers 1: 275–7]. Sends beans as evidence of crossing.
Sends drawings of two forms of workers of Cryptocerus discocephalus in response to CD’s request for examples of insects whose workers show disparity of form.
More on kidney bean crosses.
CD is informed that a certain work [unspecified] is not available separately.
Discusses the relative growth of native and foreign weeds.
News of Mrs Henslow’s death.
Studying Impatiens, which bears on CD’s problems. Though genus is endemic to India, with over 100 species, CD will be glad to know they do not run into one another.
