Describes findings of examination of geese with abnormal wings. Says old gander that sired geese is without injury or abnormality. Encloses his assistant’s report.

Asks whether he may use CD’s letters in his work [Die natürlichen Existenzbedingungen der Thiere (1880)] in order to show that Moritz Wagner has misrepresented CD’s views.

Discusses the influence of isolation and external conditions on animals, and the relative importance of the direct effect of external conditions and of selection in bringing about change.