Note 21 — Chapter I · Introductory: The Darwinism of Darwin, and of the Post-Darwinian Schools.

See Proc. Zool. Soc. June 4, 1889, for an account of the performances in this respect of the Chimpanzee "Sally." Also, for some remarks on the psychology of the subject, in Mental Evolution in Man, p. 215. I should like to take this opportunity of stating that, after the two publications above referred to, this animal's instruction was continued, and that, before her death, her "counting" extended as far as ten. That is to say, any number of straws asked for from one to ten would always be correctly given.