12 General Remarks on Cortical Fibre Arrangement [CHAP. 



avoid contusion, it is important to remember that the line of Gennari or Vicq d'Azyr is 

 nothing but a line of Baillarger exaggerated in the visual or calcarine area. 



In certain regions, for instance the superior parietal lobule, the line of Baillarger has 

 the appearance of being reduplicated ; the additional streak shows itself at a somewhat 

 deeper level and is, occasionally, the more obvious of the two. 



As to the composition of this line, it is, as Exner, Kaes and others have indicated, 

 principally made up of a plexus of delicate fibres of which the individuals can only be 

 followed for a short distance. It is more than probable that the chief components of this 

 plexus are the axis cylinders of small autochthonous cells, but it may also receive collaterals 

 from fibres of other layers. In addition to these delicate elements, fibres of stronger calibre 

 running in all directions, and also a few stout fibres, placed parallel with the surface of 

 the cortex, and traceable for a considerable distance, hold a position in the line and assist 

 in giving it prominence. The latter are akin to long association fibres which run horizontally 

 across the radiations at all levels and really pertain to the association system of Meynert, 

 while the irregularly placed stout fibres seem to be connected with the large external 

 pyramidal cells resident at this level. 



Kaes states that age has no appreciable influence on the development and representa- 

 tion of the line of Baillarger, but I gather from Vulpius' remarks that its development 

 proceeds hand in hand with that of the fibres of other layers. 



Parts between the Zonal Layer and the Line of Baillarger. 



Synonyms Superradiare Faserwerk of Edinger, Faserarme Mittelschicht of Vulpius, 

 Meynert's 2nd and 3rd layers (Kaes). 



It is difficult to find a name which will designate this part satisfactorily ; in position, 

 it of course corresponds with the lower part of the first or molecular layer and with the 

 layers of small and large pyramidal cells, superficial to the granular layer or layer of small 

 stellate cells, and some writers, including Kaes and Ramon y Cajal, wisely describe it, 

 according to its cytological relations, as " the zone corresponding to Meynert's second and 

 third layers of nerve cells," and, cumbersome as it is, this designation certainly possesses 

 the advantage of clearness. 



In Edinger's classification it becomes the superradiary network (superradiare Faserwerk), 

 distinguished from the interradiary plexus (interradiare Flechtwerk). This is an expressive 

 designation, but one which is not altogether free from objection on account of the varying 

 length of the radiations of Meynert ; for in some parts it is true that the radiations do 

 not project above the level of the line of Baillarger, and then a distinct and definite 

 superradiary zone can be determined : but in other regions, notably the temporal, the radia- 

 tions project far above this limit, indeed, many fibres make for and reach the zonal layer 

 and obviously a supraradiary layer, in the strict sense of the designation, must cease to 

 exist. Still, of the designations for this part, that of Edinger seems to have met with 

 most approval and is coming into general use in this country. I shall therefore adhere to 

 it, but instead of speaking of the supraradiary network, I shall call it the supraradiary layer. 



Concerning the nature and arrangement of fibres in this layer ; it varies considerably 

 in depth and in fibre wealth, in different parts of the cortex, and at different periods of 

 life ; the fibres which it contains are almost all of tine calibre, sparsely scattered, and placed 



