272 The Cerebral Cortex in. tins Communis 



to the field ; these are lanceolate in form, just more than medium size, intensely chromophilous, 

 and sufficiently numerous to form a distinct layer. Below this, ordinary long fusiform cells occur. 



Ectosylvian Area B. 



This is the field lying between the suprasylvian and ectosylvian sulci, and occupying the second 

 arcuate gyrus of Leuret. 



As regards nerve fibre arrangement, it differs from the "sensory" cortex above in not showing 

 the great wealth of large fibres throughout the radiary zone, and, from the cortex of the underlying 

 first arcuate gyrus, in not harbouring the peculiar collection of large, deep fibres. 



The arrangement of cells follows the common plan. External as well as internal layers of 

 large pyramidal cells are recognised (in the gyrus arcuatus primus there is no external layer). 

 There is nothing remarkable in the shape or staining reaction of the outer cells, but they are not so 

 large as corresponding elements in the postcrucial cortex, nor are they numerous. The inner cells 

 are not so chromophilous as those to which I drew special attention in describing Area No. 1. 



LIMBIC AREA. 



The limbic area has a similar distribution, and exhibits variations similar to those observed 

 in Felis. 



In the specially marked pregenual area (Litubic, A) are chromophilous. elongated cells, strongly 

 mindful of the elements to be found in the same situation in Homo. 



FRONTAL AREA. 



In transverse sections through the frontal lobe it is not easy to distinguish between anterior 

 limbic cortex and that marked frontal in the diagrams. Still, in sections stained for nerve fibres 

 there is an appreciable increase in calibre of some of the projection fibres, and also some of the 

 pyramidal cells show enlargement ; but apart from this, neither the fibre arrangement nor the cell 

 lamination presents any striking peculiarity. 



EXTRAEHINIC CORTEX. 



The strip of cortex running along the lower margin of the hemisphere, immediately outside the 

 fissura rhinica, shows features akin to those observed in Felis. 



LOBUS PYIUFORMIS. 



The territorial subdivision of the lobus pyriformis shown in the diagram has been effected on the 

 same grounds as in Felis. 



Sus COMMUNIS. 

 General Observations. 



The absence of a sulcus cruciatus and other peculiarities in the external morphology of the pig's 

 cerebrum add to the interest of its microscopic examination, but increase our difficulties in orientating 

 the various areas representing those seen in the brains of other animals. 



In addition to its distinctive external configuration, unnecessary for me to describe, as it has 

 been fully dealt with by others, the pig's brain exhibits several microscopic features unlike any 

 observed in the brains of Felis and Canis ; to these I shall briefly allude before offering details of 

 my examination. 



