Thanks for information on printing charges

and for clarifying "typical forms".

In a few days CD will go away for six weeks.

Defines the term "typical species" and discusses its use among zoologists. Cites example of type of Carnivora. Comments on general law of development of parts in animals. Cites teeth of Carnivora.

Is puzzled by CD’s question about the Viverridae; thinks if there were only one species he might regard it as an aberrant of some other group and not select it as a type of the Carnivora.

Sends Lord Enniskillen’s account of origin of the Irish yew: transplanted from the wild; propagated by cuttings thereafter. Offspring recently raised from seed are intermediate between common and Irish [weeping] yew.

Asks if J. E. Gray has returned [printing] estimates for Zoology.

Henslow has some Galapagos plants which he forgot to forward to JDH.

Thanks for earth samples. Discusses Infusoria in samples from Galapagos and Cape Verde Islands. Would like samples from other sites. Will send further results of investigations.

Encloses letter from Ehrenberg [758] about Infusoria.

Intends to visit Kew.

Thanks for shipments of earth samples. Sends copy of article describing Infusoria in samples ["Einige vorläufige Resultate … über das Verhalten des kleinsten Lebens in den Oceanen", Ber. k. Preuss. Akad. Wiss. Berlin (1844): 182–207]. Asks for more information and samples, especially from the soundings of Ross’s expedition.

Health and weather permitting, CD proposes to visit Kew.

Encloses letter from Ehrenberg [762], who wants information on deep-sea soundings from JDH’s voyage, and on isolated islands.

Encloses Ehrenberg letter, Galapagos seaweed, and specimens of Conferva.

H. Denny would like specimens of Antarctic Pediculi.

Encloses pamphlet from Ehrenberg who asks about deep-sea soundings from JDH’s voyage.

Suggests there is a direct relation between temperature and abundance of plant species.

Acknowledges note and parcel for Ehrenberg.

Considers why different areas have different numbers of species. Gives an example opposing JDH’s view that paucity of species results from vicissitudes of climate. CD has concluded that species are most numerous in areas that have most often been divided, isolated from, and then reunited with, other areas. Cannot give detailed reasons but believes that "isolation is the chief concomitant or cause of the appearance of new forms".

Discusses the connection between climate and vegetation. Believes that an equable climate is unfavourable to increase of species either by importation or modification of existing forms; illustrates his view with reference to particular floras. Hopes to acquire facts to support CD’s idea that isolation is important in producing new forms. Considers the floras of islands some of which do have distinctive species but others of which do not. Agrees that the wide ranges of cryptogams are a consequence of their means of dispersal. Asks for references to works on original creation and species mutability in order to get the best notions of "the (mad) theories of some men from Lamarck’s twaddle upwards".

Has never heard of species of same genus [of parasites] being found on both birds and mammals, or different genera and species being found on animals in the domestic and wild states. Implications of this for relationship of aperea and guinea-pig.

Sends notes on Infusoria for Ehrenberg.

Comments on distribution of species in natural orders that have local distributions. Intermediate forms between species of Lycopodium.

Origin of Antarctic brash ice.

Further on case of Lycopodium: does JDH know any genera of plants whose species are variable in one continent but not in another? Discussion on variations between floras as regards species richness, and factors affecting geographical distribution. On species, CD expects "that I shall be able to show even to sound naturalists that there are two sides to the question of the immutability of species; – that facts can be viewed and grouped under the notion of allied species having descended from common stocks". Mentions books and papers for and against species mutability. CD believes past absurd ideas arose from no one’s having approached subject on side of variation under domestication.

Would like to see Clarke’s paper

and would welcome visit from JDH.

Differences in variability of species within a single genus. Further observations on Lycopodium.

Interested in Humboldt’s river with different floras on opposite banks, and other unexplained cases of very local distributions.

Would like JDH to visit. Regrets he will not be fit to visit JDH.