Thanks AD for his Ursprung [der Wirbelthiere (1875)], which astonished CD. AD’s views, if accepted by competent authorities, will show how much we have to learn about the history of every animal. Suggests caution on "degradation principle". Comments on other views in the work. Has long seen importance of the principle of "Functionswechsel" [transfer [change!?] of function], but never enunciated it as a distinct principle.

AD is aware of revolutionary character of his pamphlet [Ursprung der Wirbelthiere]. Authorities will not agree with him. Carl Gegenbaur and Ernst Haeckel are opposed. Younger biologists are disposed to accept his views. All he can expect is to put a stop to "the Amphioxus–Ascidian affair, and to open a road for speculation and for investigation on the side of the Annelid-homology".