150 MAN AND APES. 



have great differences in brain development 

 unaccompanied by any corresponding psychical 

 diversities, and on the other we may have vast 

 psychical differences which it seems we must 

 refer to other than cerebral causes. 



Professor Huxley has sought to invalidate 

 such inferences,* first, by asserting, what is of 

 course perfectly true, that intellectual power 

 (as we daily experience it) depends, not on 

 the development of the brain alone, but also 

 on that of " the organs of the senses and of 

 the motor apparatuses." But surely to this 

 we may reply that, in these respects, no one 

 pretends even that there is much difference 

 between man and apes. 



Secondly, Professor Huxley objects that the 

 cerebral differences may be of so minute a cha- 

 racter as to have escaped observation ; and he 

 compares the brains of man and ape with 

 two watches, one of which will, and the other 

 will not, keej3 accurate time. He exclaims, 

 " A hair in the balance-wheel, a little rust on 



* ' Man's Place in Nature,' p. 102, note. 



