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.