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 visited T. V. Wollaston, who is working hard but lives too solitary a life.

There are further legal complications with William Darwin’s partnership and CD’s solicitor wants to call on JL.

Asks JL’s advice about details of William’s proposed banking partnership. CD’s solicitor is suspicious of Atherley’s long-term intentions.

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

JL’s kindness has laid William and himself "under an enduring obligation". One clause in the partnership agreement seems harsh but will probably never signify.

With some hesitation CD’s solicitor advises acceptance of partnership offered to William.

Personal regards.

William Darwin will make a botanist.

JL is thinking of moving to Brighton.

Instructions to a book seller.

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.

Has put Drosera off while amusing himself with Primula and orchids.

Dionaea is prettily adapted to weight detection.

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.

Thanks HWB for information on Volucella, although he does not know when he will use it.

Is glad HWB is beginning his book.

CD is beginning work on his orchid book.

Query on orchid homology.

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

Orchid anatomy.

Thanks for JG’s book [An introduction to the Trochilidae, or family of humming-birds (1861)], which he has read carefully. Hopes someday to use the information on the close alliance of species in large genera.

CD repudiates hybridity of birds in nature.

Intends to extract the cases of "races" or doubtful species. They show that "determination of species is not a simple affair".

Asks DO to look for nectar in Stanhopea saccata labellum. CD’s theory predicts nectar should be present, but afraid there is none.

Orchid anatomy: movement in Mormodes column.