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 o 

 any two animals or of any two men can be accurately 

 gauged bv 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 whole verte- 



6D 



Dujardin, ' Annales des Sc. Nat.' 3rd series, Zoolog. torn. xiv. 

 1850, p. 203. See also Mr. Lowne, ' Anatomy and Phys. of the Musca 

 vomitoria,' 1870, p. 14. My son, Mr. F. Darwin, dissected for me the 

 cerebral ganglia of the Formica rufa. 



VOL. I. l L 



