Birth of JDH’s second child.

Asks CD’s view of "highness" and "lowness" in animals. Gives his own for plants; extent of deviation from type, e.g., floral parts deviating from leaf.

Reading B. C. Brodie’s Psychological inquiries [1854].

CD gives his definition of "highness" and "lowness" as "morphological differentiation" from a common embryo or archetype. JDH’s view, with which CD agrees when it can be applied, is the same as Milne-Edwards’, i.e., the physiological division of labour. There is little agreement among zoologists and CD admits his own lack of clarity.

JDH on "highness" of Coniferae: they are genuine Dicotyledons, not a link to cryptogams; that is a geologists’ fallacy. Thus they are highest plants in Carboniferous.

Does not agree with CD’s "elastic" species theory. Long correspondence with Lyell on this.

CD’s view requires only that ancient organisms resemble embryological stages of existing ones. Thus "highness" in plants is difficult to evaluate because they have no larval stages. Would compare highest members of two groups, rather than archetype, to determine which group was higher. Against Forbes’s polarity and parallelism.

JDH and F. W. Binney identify Calamites specimens as pith casts. They are cryptogams related to, but higher than, Lycopodiaceae and contradict progression.

Insects found in coal.

Lyell says Stonesfield slate marsupials are actually placentals.

JDH reading Alexander Braun on individuality ["Das Individuum der Pflanze in seinem Verhältniss zur Species", Abh. K. Akad. Wiss. Berlin (Phys. Kl.) (1853): 19–122].

On individuality.

Huxley’s review exquisite, but too severe on Vestiges; sorry for ridicule of Agassiz’s embryonic fishes.

Stonesfield mammals.

J. O. Westwood deserves Royal Society Medal.

Will begin species work in a few days.

JDH’s contempt for R. I. Murchison.

There is a Cyperus species and a Pteris species endemic to hot volcanoes of Ischia. Why are there no other migrators?

Congratulates JDH on receipt of Royal Medal.

CD gathering facts on aberrant genera of insects.

Fossil leaves from Disko Island.

JDH to begin working out the botanical geography of the polar sea.

Has not forgotten CD’s request on aberrant species.

Has taken a house on Richmond Hill.

Calculating small number of species in aberrant genera of insects and plants.

Joachim Barrande’s "Colonies", Élie de Beaumont’s "lines of Elevation", Forbes’s "Polarity" make CD despair, as these theories lead to conclusions opposite to CD’s from the same classes of facts.

George Bentham’s list of aberrant plant genera. JDH appended the number of species in each genus according to E. G. Steudel’s catalogue [Nomenclator botanicus (1840–1)] and according to JDH and Bentham.

JDH speculates on effect of splitting Australia longitudinally on distribution; it becomes an argument for new creations.

JDH’s "grand speech" on receiving the Royal Medal.

Is Bentham’s list of aberrant genera biased by exclusion of genera with many species?

JDH’s belief that Aquilegia varieties are one species is consistent with their great interfertility.

Bentham’s list of aberrant genera: CD’s worry that he eliminated large genera a priori is half right. He eliminated those large, anomalous genera that virtually constitute natural orders. JDH criticises CD’s tabulations of aberrants.

Difficulty of distinguishing affinity and analogy in plants.

Debates aberrant species, e.g., Ornithorhynchus and Echidna, with JDH. CD argues they are result of extinction having removed intermediate links to allied forms.

Studying effects of disuse in wings of tame and wild ducks.

Tabulations showing that number of species in a genus is not correlated with number of genera in an order.

List of most anomalous Leguminosae [from George Bentham].

CD’s tabulation of colonists curious but explicable.

Working on Tasmanian flora; contemplating general essay on Australian distribution: Tasmania and Australia same alpine species; Swan River flora very peculiar and quite distinct from New South Wales.

Trying to establish new journal at Linnean.

Latitude overrules everything in distribution. Alpine distributions are like insular. Tabulating proportions.

T. V. Wollaston’s Madeira insects: many flightless, thus not blown to sea. TVW’s insects do not confirm Forbes’s Atlantis.

JDH criticises C. J. F. Bunbury’s paper on Madeira [J. Linn. Soc. Lond. (Bot.) 1 (1857): 1–35].

Absence of Ophrys on Madeira suggests to JDH a sequence in creation of groups.

Why are flightless insects common in desert?

Australian endemism.

CD has begun seed-salting experiments. Wants JDH to write which seeds he expects to be easily killed [in salt water].

CD’s idea that coal-plants lived in salt water like mangroves made JDH savage.