Struck by singular clarity of EH’s Generelle Morphologie. Remarks on various authors seem too severe. Severity leads the reader to take the side of the attacked person.

Making slow progress in correcting Variation.

Thanks CD for new edition of Origin [4th ed. (1866)].

Comments on CD’s criticism of the harsh tone of Generelle Morphologie. Thinks he may have harmed himself but not the cause. Believes a radical reform of the science necessary, and since most scientists take a prejudiced view of the matter, a vigorous attack is essential.

Describes his travels in Canaries, Spain, and France.

Discusses his previous criticisms of EH’s Generelle Morphologie. Fears it will make enemies.

Discusses reception of descent theory in England.

Mentions EH’s trip to Canary Islands.

Is engaged to marry Agnes Huschke. Will make wedding trip to Switzerland and Italy in autumn; therefore cannot visit CD as hoped.

Discusses present research. Comments on Protoamoeba with respect to origin of life. Says it makes question of common or separate origin of phyla unimportant.

CD to receive honorary diploma from Imperial Zoological Botanical Society in Vienna.

Sends photograph of Viennese botanist, August Kanitz.

Congratulates EH on approaching marriage.

Sorry he will not visit in autumn.

Glad EH is re-examining Protoamoeba but puzzled to think what he can find.

Describes newspaper account of criticism by Agassiz of Generelle Morphologie.

Describes his lectures on CD’s theory.

Thanks CD for copy of Variation. Comments on book.

Describes work of two protégés in Jena: Nicolas von Miklucho[-Maclay] and Anton Dohrn.

His cousin, Wilhelm Bleek, is sending an article about the origin of language.

Asks to keep book a few months longer but will return it if CD needs it [Webb and Berthelot, Histoire naturelle des Îles Canaries, vol. 3, pt 1: Géographie botanique (1840)].

Describes research on Siphonophora.

Describes life in Jena. Mentions alpine accident during wedding trip.

Delighted to hear of success of EH’s lectures.

Ernest Faivre [La variabilité des espèces (1868)] sees no reason to favour common descent of allied species.

Asks EH to pass German edition of Variation on to Gegenbaur.

Comments on work of Miklucho[-Maclay], Dohrn, and Bleek.

Has begun work on Descent.

Has received English edition of Variation. First volume of German edition came three months ago. Comments on book.

Will send copy of recent lectures on human evolution [Entstehung des Menschengeschlechts (1868)]. Gegenbaur much interested in the subject.

Considers Selachius the ancestral form of the fish and hence of all higher vertebrates. Believes their swim-bladder became lung of amphibians.

Mentions cases of hybrid crosses between rabbits and hares producing fertile offspring.

Now understands importance of swim-bladder in selachians. Always imagined animal like Lepidosiren was parent form of vertebrates.

Has been nearly a month in London, collecting facts on sexual selection from breeders and at Zoological Gardens.

Astonished at hybrid of rabbit and hare. Is it certain that work was done with hare?

Thanks CD for article by G. H. Lewes ["Mr Darwin’s hypotheses, pt 1", Fortn. Rev. n.s. 3 (1868): 353–73]. Comments on article.

Describes hybridisation experiment carried out on rabbits and hares by Dr Conrad.

Encloses description of Monera

and a phylogenetic table of vertebrates.

Mentions work on Medusae.

The controversy over CD in Germany.

Thanks for two small works.

Will read essay on man [Entstehung des Menschengeschlechts] with much interest.

Generelle Morphologie reviewed by G. Bentham ["Anniversary Address", Proc. Linn. Soc. Lond. (1867–8): lviii–c].

Extremely sceptical of hare–rabbit hybrid.

Comments on CD’s health.

Has received gold medal from Dutch Academy of Science for Zur Entwicklungsgeschichte der Siphonophoren [1869].

His Entstehung des Menschengeschlechts [1868] has been sharply attacked by the clergy.

Thanks for [Natürliche] Schöpfungsgeschichte [1868]. "What an indomitable worker you are."

Agrees with EH’s Entstehung des Menschengeschlechts [1868].

Thanks CD for comments [on Entstehung des Menschengeschlechts].

Comments on Goethe and Kant as early evolutionists.

Describes birth of his son. Mentions child’s "atavisms".

Congratulates EH on birth of child.

Mentions projected translation of Generelle Morphologie.

Comments on EH’s last book [Natürliche Schöpfungsgeschichte]. Criticises EH’s statements on palaeontology.

Comments on experience of being a father.

Discusses possible English edition of Generelle Morphologie. Mentions necessary revisions.

Thanks CD for comment on Natürliche Schöpfungsgeschichte.

Discusses problem of assigning specific times to origin of classes.

Concerning death of August Schleicher.

Comments on 5th edition of the Origin [1869];

preparation of second edition of Natürliche Schöpfungsgeschichte [1870].

The reception of CD’s theory. Mentions support of Pieter Harting and Michael Sars.

EH’s research on calcareous sponges and plans to publish monograph on them.

Suggests Englishmen who might provide sponge specimens.

Thanks CD for assistance concerning sponge specimens. Mentions Englishmen who have sent specimens. J. S. Bowerbank has not answered requests.

Sends articles dealing with sponges and Medusae. Cites passages for CD to read. Suggests passages from Entwicklungsgeschichte der Siphonophoren [1869].

Describes meeting with Sars and his trip to Norway.