Surprised at Hooker’s introducing "so organic a change as a deviation in the axis of the planet" to explain the cold of the Glacial Period.

Thanks CD for German translation of Origin.

Droughts over the summers have brought about changes in the numbers of plants and animals in the area. The small quantity of Orchestia darwinii that has survived the changes no longer includes two previously common male forms. Great changes also take place without such unusual physical conditions. The disappearance of a briefly abundant bryozoan in local caves has made way not for the return of original bryozoan inhabitants but for a completely new fauna.

Reviewing C. V. Naudin’s article ["Nouvelles recherches sur l’hybridité dans les végétaux", Ann. Sci. Nat. (Bot.) 4th ser. 19 (1863): 180–203] for Popular Science Review [5 (1866): 304–13]. Requests references.

Proposes to visit Down on Easter weekend.

Comments on cool-period MS. Still believes geographical changes principal cause of former changes of climate.

Thanks for references for his Naudin–hybridism paper [see 5029].

On the "bullae" as constant, regular generic characters in Hymenoptera. Disagrees with Louis Jurine ["Observations sur les ailes des hyménoptères", Mem. Accad. Sci. Torino 24 (1820): 177–214].

Asks, on behalf of his father, whether he might publish a new German translation of the Origin, believing Bronn’s to be inadequate.

Forgot to thank CD for his praise of tendril paper [see 4944].

Cannot come to Down on weekend because of teaching duties.

Asks to visit Down on Saturday.

Describes plans for new German edition of Origin [1867].

Oswald Heer [in Die Urwelt der Schweiz (1866)] agrees with CD that Swiss ants (Formica sanguinea) capture more slaves than do British ants. Does this contradict selection, since the British ants are exposed to harder conditions and a poorer fauna?

Sends CD comb of the Chinese honey-bee, as requested.

Calls for more study of behaviour and less of classification to determine whether descent theory can bear the weight not [only] of reasoning but of fact. Hopes CD’s intended book [Variation] will help.

Local matters.

In response to a letter from RS’s father [translation enclosed] Schweizerbart has suggested H. B. Geinitz revise Bronn’s edition of the Origin, but RS doubts he is suitable.

Reports of a tooth found in the testicle of a horse.

Hares are very fleet in countries in which greyhound coursing is developed, slow in those in which no greyhounds are kept.

Reference to description of Begonia phyllomaniaca.

Thanks for the explicit account of Pangenesis. Thinks he now follows CD’s ideas but Pangenesis is very difficult and speculative.

Oliver has lost his little girl.

Sends copies of Science gossip and The leisure hour.

Enjoyed visit.

His criticism of Primula fertility referred to table 2 [Collected papers 2: 56] where weight of seeds produced from good pods by long-styled homostylous cross and short-styled heterostylous cross are virtually identical.

Pleased CD does not consider review of his works prejudiced [Anon., "Darwin and his teachings", Q. J. Sci. 3 (1866): 151–76].

Supports gradual development of species over time.

Confused by the metaphysical view implied in the analogy between a creative power that has made new species and artificial selection governed by human reason (Origin, 3d ed., p. 492).

Doubts natural selection.

Cites his discussion of the origin of Infusoria [Proc. R. Soc. Lond. 14 (1865): 546–7].