Thanks JL for identifying Catasetum saccatum.

Writes of his interest ("more than almost anything in my life") in orchids, but fears he is rash to publish.

Continued discussion of Jamieson’s Glen Roy theory. Mentions river erosion of glaciers. Quotes from old letter to CL [1116].

Is working hard on orchids; fears subject is too complex for the public.

G. B. Sowerby, Jr has done the drawings for Orchids woodcuts. Calls JM’s attention to the fact that a first-rate cutter must be employed.

Replies to CD’s query (see 3778): the queens or females of the humble bees are not fertilised in the air. Offers a number of observations relating to the fertilisation of bees and wasps, which he has made in the course of sixty years.

Mr Campbell (recommended by H. Spencer) would be a treasure but doubts any man has patience to experiment at another’s suggestion.

Jocular comments about THH’s audacity in doubting Catasetum.

Tells of a shooting competition at Down.

Has been working hard at orchid drawings with G. B. Sowerby, Jr.

Ice could not have formed the blockages in Lochaber unless in every case the water escaped over some col into a contiguous valley on the same watershed, or into the eastern watershed. Supposes that the cols were not land-straits, but the places where the lakes were drained when forced to flow the wrong way.

Comments especially on the "intermediate shelf" problem of Glen Roy; views of Jamieson and Milne. CD "cannot help a sneaking hope that the sea might have formed the horizontal shelves".

JDH’s work on Gnetum: a living fossil.

Orchid anatomy.

Encloses lists of orchids and other specimens he would be interested in seeing.

Discusses his observations at Glen Roy. Mentions glaciers seen by Hooker in the Himalayas. Discusses problems of glacier–lake theory.

Thanks WBC for his account of glacial action in Australia. A mundane cooler period would throw a flood of light on geographical distribution. Has sketched a large MS on subject but does not know whether he will live to publish it.

Questions WBC on striated granite boulders.

Asks him to make a botanical experiment on insect fertilisation.

Sends thanks for an informative letter;

would be grateful for any orchids; names some he would particularly like.

Subscribes to present for Mrs J. T. Quekett only on condition that no public testimonial is planned for JTQ.

Acropera anatomy puzzling. Malaxis anatomy deciphered.

Discusses affairs at Down and Southampton.

Owen’s new résumé of his brain doctrine ["On the cerebral character of man and ape", Ann. & Mag. Nat. Hist. 3d ser. 7 (1861): 456–8]; an attack on CD’s views. Quotes Owen on cavillers and controversialists.

Asks H. W. Newman whether the queen humble-bee is fertilised on the ground or in the air, and whether the fertilisation often takes place as late as September. [Newman’s reply follows CD’s letter.]