The Origin converted him from a Linnean interpretation of flowers and mosses.

Glad that CD appreciates his continuing work on mosses, in support of natural selection.

Plans to repeat CD’s orchid experiments.

Sends interpretation of the floral anatomy of Lopezia miniata.

Has learned that Fritz Müller is HM’s brother.

Thanks for "Climbing plants" offprint and for references on fertilisation of flowers.

Considering the bounty of work already done, he is looking for something original to do.

Subularia does not grow in Westphalia.

Made aware by Asa Gray of error with respect to Cypripedium. Does not doubt it is self-fertilised.

Müller’s observations on orchids excellent.

Thanks for German version of Origin [1867].

Dipterous insects are adapted to eating pollen rather than only to sucking nectar. He describes such adaptations in two dipteran species.

Thanks CD for his photograph.

Intends to start experimenting with mosses to determine which differences in structure are effected by altered conditions of life.

Offers to undertake publication of English translation of Fritz Müller’s Für Darwin. W. S. Dallas will translate it.

HM is certain his brother Fritz would like to see Für Darwin translated into English by Dallas. He will make arrangements with the German publisher.

Two friends are writing Darwinian works: Adolf Speyer on phylogeny of Lepidoptera

and August Röse on genealogy of mosses.

Has heard from W. Engelmann of Leipzig; he is willing to let CD have the woodcuts to Fritz Müller’s work [Für Darwin (1864)] for 22 thalers.

Pleased HM says good words for Pangenesis.

Thanks CD for the English edition of his brother’s book [Fritz Müller, Facts and arguments for Darwin (1869)]

and for CD’s memoir on orchids ["Fertilization of orchids", Collected papers 2: 138–56].

Would like Frederick Smith of the British Museum to determine whether or not some unidentified Westphalian bees are new species.

HM intends studying bees to find evidence supporting CD’s theories. His work has shown him there are problems in separating species from varieties, and has also revealed many surprising instances of variation in habits.

Interested that HM is studying structure of insects in relation to flowers.

Is preparing a work on fertilisation of flowers, and wants to add a list of works containing observations on cross-fertilisation of plants. Asks CD for any references he may have.

Comments on HM’s paper ["Anwendung der Darwin’schen Lehre auf Bienen", Verh. Naturhist. Ver. preuss. Rheinland 29 (1872): 1–96];

sexual selection in bees.

Encloses account on habits of Bombus.

Thanks CD for MS on the routes of male bees.

His "Fertilisation of flowers" is complete [Die Befruchtung der Blumen (1873)].

Sends his book [Die Befruchtung der Blumen (1873)]. Hopes CD will publish an opinion of it.

Comments on HM’s book [Die Befruchtung der Blumen (1873)]. Particularly glad to read historical sketch and discussion of work of C. K. Sprengel.