FUNCTIONS OF THE BRAIN 



967 



ear, and also to some extent of the ear on the same side. This is 

 gradually recovered from. If it is destroyed on the left side there 

 is also the peculiar condition called ' word-deafness,' which will be 

 referred to directly (p. 972). In deaf-mutes the first temporal 

 convolution may be atrophied. There is evidence that the posterior 

 corpora quadrigemina and the mesial geniculate body form an in- 

 ferior relay on the route between the fibres of the auditory nerve 

 and the temporal cortex. There are indications that within the 

 auditory area so-called ' musical centres ' exist that is, an orderly 



SYLVIA N 



FISSURE 



Fig. 395. Lateral View of Left Hemisphere with Sensory Areas: Man. The front 

 of the brain is towards the left. 



arrangement of the cell-bodies of the neurons that have to do with 

 the perception of pitch, so that a limited lesion may cause deafness 

 to notes of a particular pitch when it is situated on one .part of the 

 area, and deafness to notes of a different pitch when it is situated 

 elsewhere (Larionow). 



Centre for Smell. As to the position of the centre for smell, direct 

 experiment on animals cannot teach us much, for if the outward 

 tokens of visual and auditory sensations are dubious and fluctuating, 

 still more is this the case with the signs of sensations of smell. A 



