Puzzled by function of orchids’ rostellum.

Orchids’ pollen concentrated in two pollinia; hence one flower can fertilise only two others. This may explain precision of orchid pollination mechanisms.

Has found function of rostellum: modified stigma guarantees attachment of pollinia.

Personal regards.

William Darwin will make a botanist.

Orchid anatomy. Requests Lindley’s work on orchids [The genera and species of orchidaceous plants (1830–40)].

After much crossing, has worked out meaning of dimorphism in Primula.

CD’s orchid paper is to become orchid book [Orchids].

Primula paper is done [Collected papers 2: 45–63].

Bates agrees with CD on neuter ants.

Orchids.

Repeating experiment of C. F. v. Gärtner to study Huxley’s idea of physiological species.

Query on orchid homology.

Critical of F. A. Bauer on orchids [Illustrations of orchidaceous plants (1830–8)].

Orchid anatomy.

Orchid anatomy: movement in Mormodes column.

Orchid anatomy. Catasetum exemplifies slight modification of structure leading to new structure.

Orchid anatomy. Wind as agent of self-fertilisation in orchids.

Orchid anatomy. Movements of labellum.

Repeating Gärtner’s experiment with Verbascum varieties.

JDH’s work on Gnetum: a living fossil.

Orchid anatomy.

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

Acropera anatomy puzzling. Malaxis anatomy deciphered.

Orchid anatomy.

Orchid homologies.

Sensitive responses in Catasetum.

Acropera becoming clear.

T. F. Jamieson impressed by JDH’s work on Himalayan glaciers.

Asks JDH to look at movement of labellum in an orchid.

Rostellum of Masdevallia.

JDH’s Fernando Po case.

Madeiran fauna pre-glacial according to Oswald Heer.