1903.] Histological Studies on Cerebral Localisation. 491 



VI. Temporal Lobe. 



Audito-Sensory Area. The first important field is a small one 

 occupying the transverse temporal gyri, and therefore concealed 

 within the Sylvian fissure. As this is the first temporal cortex to 

 become medullated, as it seems to be the terminus of the central 

 auditory tract, and as there are clini co-pathological reasons for believing 

 that its destruction is equivalent to the production of complete deaf- 

 ness, the assumption is favoured that it constitutes the primary auditory 

 centre. But further evidence on this point is needed, and the results 

 of the examination of the part in cases of congenital or long-standing 

 deafness of peripheral origin would be welcome. 



Audito-Psychic Area. -This area, of ready definition, covers the 

 posterior three-fifths of the first temporal gyrus and is thus closely 

 related to the one just mentioned. It is seen to correspond with the 

 well-known centre for word-deafness, but in reference to that disability 

 it must be indicated that the structure of this region is alike in the 

 two hemispheres, and without denying the dominant psychic action of 

 the area in the left hemisphere the opinion is expressed that the 

 right side shares that function, because in the only recorded cases 

 of complete, uncomplicated and irrecoverable word-deafness, verified 

 by an autopsy there are but two a bilateral lesion has been dis- 

 covered. 



Similar areas are defined with equal readiness in the anthropoid 

 brain. 



Common Temporal Area. The remainder of the temporal cortex 

 shows a uniform type of structure stamped by a poverty in fibres 

 and cells of large size, and it has been disappointing to discover that 

 the angular gyrus is not endowed with any specialised arrangement. 



VII.Limbic Lobe. 



Pyriform or Olfactory A rea. Histology supports comparative anatomy 

 in suggesting that the lobus pyriformis must be regarded as the 

 principal cortical centre, although not the sole one, governing the 

 olfactory sense. Remarkable superficially-placed clusters of large 

 stellate cells and a tendency on the part of the projection fibres to 

 gain the surface, characterise its structure, and the rudimentary fissura 

 rhinica forms a most definite limit. 



Hippocampal Area and Cornu Ammoms.The cortex covering the 

 wall and lip of the fissura hippocampi differs from the above and 

 also from that of the gyrus dentatus, but the function of this part 



remains obscure. 



Limbic Area. This practically covers the whole gyrus formcatus. 

 In the pregenual part deep chromophilous cells may be seen, resem- 



