Returns letter mailed by mistake [see 4361].

Hopes CD will accept gift of his Radiolarien [Die Radiolarien, 2 vols. (1862)].

Has received EH’s Die Radiolarien. Drawings admirably executed. Had no idea such low animals could develop such beautiful structures.

Thanks for paper ["Über die Entwicklungstheorie Darwins", Amtl. Ber. Versamml. Dtsch. Naturforsch. Aerzte 38 (1863): 17–30]. Delighted EH confirms his views. Many in England afraid to express views openly.

No book has made such a powerful impression on EH as the Origin. Most older German scholars opposed to it, but number of supporters growing among the young. Fortunately strength of religious dogmas now small among educated Germans. Situation in Jena especially favourable. Defended CD’s theory last year at Congress of German Scientists in Stettin.

Intends special study of jellyfish.

Plans general work on natural history.

Hard fate [death of Anna Sethe Haeckel] has made EH indifferent to criticism.

Colleagues August Schleicher and Carl Gegenbaur also convinced by CD’s theory.

Thanks for praise [of Origin].

Comments on EH’s Die Radiolarien.

Grieved EH has suffered calamity [death of Anna Sethe Haeckel].

CD recovering from long illness.

Doing easy botanical work.

Mentions variability.

Discusses reception of CD’s views in Germany.

Sends photographs of himself and his late wife [Anna Sethe]. Describes death of his wife.

Plans trip to the Alps.

Thanks CD for biographical information about himself.

Mentions Goethe as early evolutionist.

Cites Kant as early supporter of epigenesis.

Mentions criticism of CD’s theory by R. A. von Kölliker ["Über die Darwin’sche Schöpfungstheorie", Z. Wiss. Zool. 14 (1864): 174–86].

Can understand EH’s feelings on death of his wife.

CD was impressed by manner in which species in South America are replaced by closely allied ones, by affinity of species inhabiting islands near S. America, and by relation of living Edentata and Rodentia to extinct species. When he read Malthus On population, the idea of natural selection flashed on him.

Agrees with EH’s remarks on Kölliker ["Darwin’sche Schöpfungstheorie", Z. Wiss. Zool. 14 (1864): 174–86].

Asks EH to thank Carl Gegenbaur [for Vergleichende Anatomie der Wirbelthiere (1864)].

Thanks CD for notes concerning the development of his ideas about the origin of species. Says August Schleicher and Carl Gegenbaur also interested.

Names new supporters of CD’s theory, including Max Schultze, Rudolf Leuckart, and Alexander Braun. Zoologists have been more interested than botanists.

He is writing a general work on the relationships among animals [Generelle Morphologie der Organismen (1866)].

Comments on Fritz Müller’s Für Darwin [1864].

Gegenbaur is revising his Grundzüge der vergleichenden Anatomie [2d ed. (1870)] to accord with evolution.

Thanks CD for copy of book on balanids [Living Cirripedia, vol. 2].

Sends Living Cirripedia [vol. 2].

Has employed translator for Fritz Müller’s book [Für Darwin (1864)].

Thanks for paper and speech.