Sends specimens of Tortrix, which illustrate the extraordinary variation of markings in two or three species. In every family of Lepidoptera there seem to be species extremely prone to vary and in some localities they vary more than in others.

CD is "as ignorant of mechanics as a pig", but glaciers have interested him greatly. Hopes to hear that JT’s experiments with ice will explain the freezing together of ice below the freezing point.

The variations of Peronea caused A. H. Haworth and J. F. Stephens to create 30 or 40 species based on colour and markings. HD was first to be convinced these would be reduced to two.

Discusses species that closely resemble one another;

cites species that differ in variation in different localities;

in some double-brooded species the broods differ markedly in size and colour.

Encloses his list of varieties of Peronea.

Sends information on the speed at which his pigeons fly various distances.

Discusses the ranges of alpine species in U. S. and considers the possible migration routes of such species from Europe.

Lists those U. S. genera which he considers protean and describes the U. S. character of some genera which are protean in Europe.

Describes how he distinguishes introduced and aboriginal stocks of the same species.

The species of Mollusca at Mauritius are almost all different from those of surrounding islands, which confirms the belief that the islands were elevated from the ocean rather than separated from the continent by volcanic action.

HCW is trying to define what CD means by "variable" genera.

Comments on transport of ducks to Jamaica by hurricanes,

fish feeding on seeds,

and sterility of birds in captivity.

Describes problems of classifying species in highly variable genera. Lists highly variable genera. Comments on the list of Asa Gray. Says species may be made to appear more or less variable according to whether a genus is divided into few or many species.

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

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

Protean genera.

Ranges of species in large vs small genera: Asa Gray’s compilation fits CD’s expectation.

CD studies seedling mortality in his weed garden.

JDH’s work on Indian flora.

Sends account of his successful experiments in feeding wheat seeds to minnows.

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].

Reports on wheat in the stomach of fish he caught.

Independence of variation from climate shown by several plant genera; CD asks for confirmation.

Progressing with book [Natural selection].

Recommendations of books of general interest [for the Royal Society library]. These include [Louis] Agassiz’s works, [William] McGillivray’s [History of] British birds, and David Low’s [On the domesticated animals of the British Islands].

Comments on current candidates for the Royal Society.

JDH cites W. H. Harvey’s observations on Fucus and David Don’s on Juncus as examples of variations that are independent of climate. There are many such cases. Gives his working scheme for categorising variation.

Thanks JDH for response on variation. Studying variations that seem correlated with environment, e.g., north vs south, ascending mountains.

CD’s weed garden: observations on slugs killing seedlings.

Seed-salting. One-seventh of the plants of any country could be transported 924 miles by sea and would germinate.

Lists groups of insects absent from the Madeiran fauna.

Has found no reference to construction of bees’ cells in works referred to by CD. Describes cell of Osmia atricapilla. Hive-bees’ cell was described at Entomological Society.