.Chap. IV. 
MANNER OF DEVELOPMENT. 
145 
man. A great reduction of the canine teeth in the 
males would almost certainly, as we shall hereafter see, 
have affected through inheritance the teeth of the 
females. 
As the various mental faculties were gradually de- 
veloped, the brain would almost certainly have become 
larger. No one, I presume, doubts that the large size 
of the brain in man, relatively to his body, in compari- 
son with that of the gorilla or orang, is closely con- 
nected with his higher mental powers. We meet with 
closely analogous facts with insects, in which the cerebral 
ganglia are of extraordinary dimensions in ants; these 
ganglia in all the Hymenoptera being many times larger 
than in the less intelligent orders, such as beetles . 69 
On the other hand, no one supposes that the intellect of 
any two animals or of any two men can be accurately 
gauged by the cubic contents of their skulls. It is 
certain that there may be extraordinary mental activity 
with an extremely small absolute mass of nervous 
matter : thus the wonderfully diversified instincts, 
mental powers, and affections of ants are generally 
known, yet their cerebral ganglia are not so large as the 
-quarter of a small pin’s head. Under this latter point 
of view, the brain of an ant is one of the most marvellous 
atoms of matter in the world, perhaps more marvellous 
than the brain of man. 
The belief that there exists in man some close relation 
between the size of the brain and the development of 
the intellectual faculties is supported by the comparison 
of the skulls of savage and civilised races, of ancient and 
modern people, and by the analogy of the w T hole verte- 
69 Dujardin, 1 Annales des Sc. Nat/ 3rd series, Zoolog. tom. xiv. 
1850, p. 203. See also Mr. Lowne, 1 Anatomy and Phys. of the Musca 
mmitoria 1870, p. 14. My son, Mr. F. Darwin, dissected for me the 
cerebral ganglia of the Formica rufa. 
VOL. I. 
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