Thanks HBD for his lectures On the germs and vestiges of disease [1861].

Thinks his reasoning that the V. M. F. ("force exhibited in the operations of life") is not a "given quantity" is satisfactory.

How far the conditions of life affect the forms of organic life puzzles CD more than any other part of his subject. Thinks he may have underrated its importance in Origin.

Asks for source of the quotation on regeneration in HBD’s work.

Tells JS Acropera capsule should be left to grow.

JS was correct on "bud-variation" in fern frond.

Does not believe Primula structure necessarily related to dioecism, but the difference in fertility of the two forms forced him to admit the possibility.

Thanks for letter and pamphlet.

His approbation of Origin is extremely gratifying, especially since Origin produced no effect whatever in France.

Sends belated thanks for the useful facts which he plans to quote. [See 3963.]

A note reminding THH to examine the rudiment of the 6th toe on the hind foot of a Batrachian.

Criticises Dana’s classification of man and his use of fore-limbs as a basis for systematic classification.

Discusses his reading and understanding of Origin.

Replies to CD’s letter: dimorphism common in Ceylon Rubiaceae. [See Forms of flowers, p. 286.]

Hoped to meet CD at the Linnean Society to discuss pigeon and poultry breeding experiments.

Thanks for "monkey book" [Evidence as to man’s place in nature (1863)].

Must wait till he has finished Lyell [Antiquity of man (1863)].

Sends Acropera capsule for CD to dissect.

Will try to raise Acropera from seed (never done before in Britain) to examine its sexual forms.

Studying primroses, parthenogenesis, and reproduction of some cryptogams.

Received maize varieties from CD.

Discusses experiments that WBT will undertake to investigate whether particular pigeon and poultry crosses produce sterile hybrids.

Discusses the structure and particular uniformities of the Shropshire coal-seams and surrounding strata; speculates on their origins.

Received JDD’s book [Manual of geology (1862)]

and pamphlet on man ["On the higher subdivisions in the classification of mammals", Am. J. Sci. 2d ser. 35 (1863): 65–71].

Fully admits JDD’s objections are valid. But is convinced of the general truth of his own views (with much incidental error), because they embrace so many phenomena and explain them.

Discusses some mistakes Owen has made;

Falconer’s disagreement with Owen ["On the mammalian genus Plagiaulax", Q. J. Geol. Soc. Lond. 18 (1862): 348–69].

Has not answered CD’s former letters. Has been ill. Will look up fish business as soon as he is square again.

Dining arrangements.

Thanks JS for the very large Acropera capsule. CD has perhaps made a blunder about the sex of Acropera.

JS was right that successive homomorphic generations of Primula breed true.

Plants, safely arrived from Kew, fill new greenhouse.

Glad RF approves of book [Origin].

Impossible in many cases to conjecture how structures acquired.

Comments on degeneration of civilised man.

Recommends Lyell’s book [Antiquity of man (1863)].

Quotes praise of AG’s pamphlet [see 2938].

Comments on U. S. politics.