vi] T;ijH'g of Arrangement of Nerre Fibres 151 



v 



and vice versa, if they are to be regarded as running in the opposite direction, that is to 

 say if they be corticifugal fibres. But on this point I shall have more to say further on. 

 Although scattered members of this system of fibres are present in the line of Baillarger 

 and even in the supraradiarv Held, yet they are distinctly more numerous in the depths 

 of tin- cortex immediately overlying the white substance, and in thin sections they may be 

 MTU in the white substance itself. Another noteworthy point is that though some of them 

 directly join the radiating fasciculi the majority pass straight across. Finally, I would say, 

 that their actual calibre is hardly so great as that of similar large fibres seen in the 

 postcentral and calcarine cortex. 



Briefly stated, the distinctive features of this type of cortex are the presence in the 

 radiary zone of numerous large fibres, the existence of a line of Kaes, and the general wealth 

 of fibres in all layers. 



FIBRE ARRANGEMENT IN THE FIRST TEMPORAL GYRUS (HINDER PART). TYPE No. 2. 



(Plate XII, fig. 2.) 



The type of fibre arrangement in this area is homologous to that found on the outskirts 

 of other regions, such as the precentral and visuo-sensory, and the term " intermediate " is 

 the best expression applicable to its characters. In describing its features it will be con- 

 venient to draw comparisons between it and the other two temporal types. 



Zonal Layer. 



The zonal layer must be described as being above the average development, but while 

 it is better represented here than in the general temporal field, it is not so dense as in 

 the concealed area just described, and fibres of large size are distinctly uncommon. 



Supraradiary Layer. 



Here again, while the general wealth of fibres is obviously greater than in the general 

 temporal region, it is not so profound as in the transverse temporal convolutions ; further, 

 the line of Kaes noted as present in the latter region is now scarcely discernible. 



Line of Baillarger. 



This line is distinctly seen with the naked eye and is of considerable breadth, but it 

 does not contain so many fibres of large calibre as it did in the part previously described, 

 and hence loses in prominence. There is only a faint attempt at a reduplication of the line. 



Radiations of Meynert. 



The volume of the radiations is intermediate between that of the transverse temporal 

 and common temporal bundles. The individual fasciculi are of great length, and exhibit a 

 tendency to pierce the line of Baillarger and spread out in the supraradiary layer; they 

 are also fairly rich in coarse fibres. 



