Mental evolution in animals. With a posthumous essay on instinct by Charles Darwin.

Includes the first editon of Darwin's most significant contribution to psychology. This was part of Chapter 10 of Darwin's unpublished "big book" on the origin of species. Romanes attempted, with Darwin, to develop a theory of mental evolution in which development of successively higher stages of intelligence, including that of man, could be explained in terms of natural, historical causes. Digital facsimile from the Biodiversity Heritage Library at this link.