Summary

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.

Summary

Urges AG to generalise from his observations on the flora of the northern U. S.

Expected to find separation of sexes in trees because he believes all living beings require an occasional cross, and none is perpetually self-fertilising. The multitude of flowers of a tree would be an obstacle to cross-fertilisation unless the sexes tended to be separate.

The Leguminosae are CD’s greatest opposers; he cannot find that garden varieties ever cross. Could AG inquire of intelligent nurserymen on the subject?

Thanks AG for information on protean genera; much wants to know whether their great variability is due to their conditions of existence or is innate in them at all times and places.

Summary

Asks JL not to call as he has a "very old friend" [J. S. Henslow] coming to visit him.

Yesterday visited poultry show at Crystal Palace.

Summary

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.

Summary

Survey of species with well-marked varieties: JDH’s Labiatae case a "great blow", but result is very generally consistent.

Summary

Returns CD’s lists [sent with 2184]. Confusion in genera of Silene is great in continental botanic gardens. One would have to know whether C. F. v. Gärtner had the right names for species in his experiments.

Summary

Thanks for AG’s remarks on disjoined species. CD’s notions are based on belief that disjoined species have suffered much extinction, which is the common cause of small genera and disjoined ranges.

Discusses out-crossing in plants.

Has failed to meet with a detailed account of regular and normal impregnation in the bud. Podostemon, Subularia, and underwater Leguminosae are the strongest cases against him.

Summary

Comments on species with disjoined ranges; does not feel, despite CD’s expectations, that they tend to belong to small families.

Gives the proportion of U. S. trees in which the sexes are separate [see Natural selection, p. 62].

Summary

For his studies on fertility of crosses, asks GB to mark a list of pairs of Cucubalus as to whether they are varieties of the same species, or distinct species.

Summary

Thanks him for information concerning Crustacea.

Comments on natural history study in the U. S.

Mentions work done by Huxley on Crustacea ["Description of a new crustacean", J. Geol. Soc. Lond. 13 (1857): 363–9];

John Lubbock on larvae of Diptera.

Summary

Thanks GB for his answers [to 2184], which were as explicit as he expected. Cucubalus viscosus and italicus are extremely sterile together; all other forms extremely fertile. Other instances of infertility found by Gärtner.

Summary

Thanks GB for his help on naturalised plants; comments on spreading of plants.

Wants to quote GB on the names of species and varieties of Silene on which C. F. von Gärtner experimented.

Thinks GB will be disappointed in his book [Natural selection]. "It will be grievously too hypothetical."

Summary

Has come to think his brains were not made for thinking – he immediately feels better when at Moor Park.

News of his family.

Summary

Thanks AG for his criticisms of CD’s views; finds it difficult to avoid using the term "natural selection" as an agent.

Discusses crossing in Fumaria and barnacles.

Has received a naturally crossed kidney bean in which the seed-coat has been affected by the pollen of the fertilising plant.

Finds the rule of large genera having most varieties holds good and regards it as most important for his "principle of divergence".

Summary

Encloses an abstract of his ideas on natural selection and the principle of divergence; the "means by which nature makes her species".

Discusses varieties and close species in large and small genera, finding some data from AG in conflict with his expectations.

Has been observing the action of bees in fertilising kidney beans and Lobelia.

Summary

Species with marked varieties.

Dana’s pamphlet also too metaphysical for CD.

Natural selection chapter on hybridism completed.

Doubts JDH will resist theory in his introduction to Flora Tasmaniae.

Summary

Asks to borrow several Floras. Must redo calculations as John Lubbock has shown him an important error.

Summary

Inquiries on effect of dry heat on temperate plants for glacial chapter.

Summary

Separation of sexes in trees [U. S.].

Do plants offer positive evidence for "continuous land" theory?

Protean genera.

Summary

Finds CD’s results [of his survey of well-marked varieties from A. P. and Alphonse de Candolle’s Prodromus systematis naturalis regni vegetabilis (1824–73)] "very curious and suggestive". Thinks the Labiatae will present an obstacle to him as it is a very large and distinct order with well-defined species and genera. Would like to see him tackle more volumes of Candolle’s Prodromus, as his case can only be established by evidence from mundane plants. CD should beware of generalising from local species variability. A comparison of C. C. Babington’s and G. Bentham’s [British] Floras [Babington Manual of British botany (1843, 4th ed., 1856); Bentham Handbook of British flora (1858)] would be invaluable. Suggests CD write to Ferdinand Müller and Charles Moore in Australia. Moisture favouring extension of species is important for CD’s view.