es of instinctive differentiation and thus furthering
the psychological activities which are included under the comprehensive
term "intelligent."

In "The Descent of Man" Darwin dealt at some length with intelligence
and the higher mental faculties. ("Descent of Man" (1st edition),
Chapters II, III, V; (2nd edition), Chapters III, IV, V.) His object, he
says, is to show that there is no fundamental difference between man and
the higher mammals in their mental faculties; that these faculties are
variable and the variations tend to be inherited; and that under natural
selection beneficial variations of all kinds will have been preserved
and injurious ones eliminated.

Darwin was too good an observer and too honest a man to minimise
the "enormous difference" between the level of mental attainment of
civilised man and that reached by any animal. His contention was that
the difference, great as it is, is one of degree and not of kind. He
realised that, in the development of the mental faculties of man,
new factors in evolution have supervened--factors which play but
a subordinate and subsidiary part in animal intelligence.
Intercommunication by means of language, approbation and blame, and
all that arises out of reflective thought, are but foreshadowed in the
mental life of animals. Still he contends that these may be explained
on the doctrine of evolution. He urges (Ibid. Vol. I. pages 70, 71;
(Popular edition), pages 70, 71.)" that man is variable in body
and mind; and that the variations are induced, either directly or
indirectly, by the same general causes, and obey the same general laws,
as with the lower animals." He correlates mental development with
the evolution of the brain. (Ibid. page 81.) "As the various mental
faculties gradually developed themselves, the brain would almost
certainly become larger. No one, I presume, doubts that the large
proportion which the size of man's brain bears to his body, compared to
the same proportion in the gorilla or orang, is closely connected with
his higher mental powers." "With respect to the lower animals," he says
("Descent of Man" (Popular edition), page 82.), "M.E. Lartet ("Comptes
Rendus des Sciences", June 1, 1868.), by comparing the crania of
tertiary and recent mammals belonging to the same groups, has come to
the remarkable conclusion that the brain is generally larger and the
convolutions are more complex in the more recent form."

Sir E. Ray Lankester has sought t