Will use Boltenia case cautiously, if at all.

Polyzoa.

Bisexualism in Flustra and Ascidia.

Grateful for Siebold’s wonderful facts [C. T. E. von Siebold, On a true parthenogenesis in moths and bees (1856), trans. by W. S. Dallas (1857)].

Vitality of spermatozoa.

Hybridisation of bees. Bees are in one respect his greatest theoretical difficulty.

CD still convinced about the relation of cement receptacles and ovarian tubes [in Crustacea].

Birth of C. W. Darwin.

Pleased by what THH says on cement glands and organs in higher Crustacea. Content to be moderately right.

Hopes THH will dissect the Conchoderma.

Asks for cases of organs in which there is no apparent transition from other organs or in which transition can be shown in an unexpected way and for instances of odd and inexplicable connections between parts, such that if one part varies the other varies also.

Congratulations [on Mrs H’s delivery].

Balanus balanoides positively identified by CD.

Asks THH question on flow of glaciers after ice has been fractured and fragmented.

CD had to leave Royal Society lecture [joint paper by THH and J. Tyndall, "On the structure and motions of glaciers", Philos. Trans. R. Soc. Lond. 147 (1857): 327–46] before the end because of headache.

Thanks THH for his response on glacial movement. Hopes Tyndall will experiment on broken ice and explain how two pieces of ice can freeze together.

Sorry to hear of THH’s row with Richard Owen.

Asks THH’s opinion on embryological views of G. A. Brullé [Ann. & Mag. Nat. Hist. 13 (1844): 484–6] and F. M. Barnéoud [Ann. des Sci. Nat. ser. 3, Bot. 6 (1846): 268–96] and on Milne-Edwards’ classification.

Has been reading John Goodsir ["On the morphological constitution of the skeleton of the vertebrate head", Edinburgh New Philos. J. 2d ser. 5 (1857): 123–78].

Has embryology of bats ever been worked out?

THH comments on G. A. Brullé’s paper ["Researches upon the transformations of the appendages of the Articulata", Ann. & Mag. Nat. Hist. 13 (1844): 484–6].

Thanks THH for his cautionary response on Brullé, but departs from THH in thinking that Barnéoud, if true, would shed light on Milne-Edwards’ proposition that the wider apart classes of animals are the earlier they depart from common embryonic plan.

Thanks for three last lectures and the account of cirripedes.

Difficulty of classifying the higher groups.

Agassiz’s superficiality and wretched reasoning powers. But he stirred up Europe on glaciers. Lyell has been working on their effects – testing work of others.

CD believes "Natural Systems" ought to be simply genealogical. "Time will come when we shall have true genealogical trees of each great kingdom of nature."

On classification and possibilities of a scientific morphology and zoology. CD’s "pedigree business" is important for physiology but has nothing to do with pure zoology any more than human pedigree has to do with the census. Zoological classification is a census of the animal world.

Thinks naturalists look for something further than Cuvier’s view of classification. Poses a theoretical problem on the classification of the races of man to prove that a genealogical system is best.

Glad THH has taken up aphid question versus Owen ["On the agamic reproduction and morphology of Aphis", Trans. Linn. Soc. Lond. 22 (1858): 193–236].

Fertilisation and inheritance discussed. Speculates that fertilisation may be a mixture rather than a fusion. Can understand in no other way why crossed forms tend to go back to ancestral forms.

THH’s catalogue [THH and R. Etheridge, A catalogue of the collection of fossils in the Museum of Practical Geology (1865), part published in 1857] best résumé he has seen of science of natural history. On classification he is not quite sure that he wholly goes along with THH. Encloses a few criticisms of THH’s preface.[enclosure survives as copy only].

Congratulations on birth of THH’s daughter [Jessie].

On aboriginal dun colour of horses.

Examples of inaccuracies and perpetuation of errors [on hybrids] by "compilers, of which I am one".

CD’s reasons for not signing the memorial requesting removal of natural history exhibits from British Museum. Less sure about moving botanical specimens to Kew. His notion of museum organisation.

Hooker has convinced him that move of British Museum by Government is anticipated. He is now willing to sign the memorial. Still fears for library needs, and objects to distant Kensington site. Lyell should be asked to sign.

Has had some misgivings about the memorial but now thinks his fears were vain and cowardly. Regrets R. I. Murchison was not told in advance. His low opinion of the Government and B. Disraeli.

K. E. von Baer’s view of the air bladder of fishes.