ll] General Itentftrkx <ui ('orfinif Fibre ArranijeiiK'nt 13 



in all (liivrtii>ns, anil must be the axis cylinders and collaterals of the small and medium- 

 sized pyramidal cells placed hereabouts. Immediately beneath the zonal layer the fibres are 

 usually least numerous, and the network which they form increases in complexity as the line 

 of Baillarger is approached. As has been mentioned already, the lower part of the layer 

 is penetrated by the upper extremities of the fibres contained in the radiary projections, 

 and these fibres along with the collaterals of axis cylinders of the larger pyramidal cells, 

 add to the richness of the plexus in the deeper levels. I have also mentioned in my 

 description of the zonal layer, that certain fibres, coupled with the name of Martinotti, 

 reached it from subjacent parts, and I may now add, that in their passage through the 

 supraradiary layer these may be recognised by their direct vertical course and by having 

 a greater calibre than the generality of fibres found in this situation. 



In addition to the fibres of Martinotti, others of like size but having a horizontal direc- 

 tion are to be alluded to. Such fibres were first noted by Emminghaus, but they are now 

 associated with the names of Kaes and Bechterew and constitute what are known as Kaes' 

 and Bechterew's lines. Kaes' line is not easily identified as such, but has been described as 

 being composed of thick medullated fibres, closely applied to one another, lying at the level 

 where the first and second layers of nerve cells join, and having the nature of association 

 fibres. Kaes has seen his line in many regions and believes that it indicates one of the final 

 phases in developmental organisation. Bechterew's line is placed immediately below the zonal 

 layer and is composed of thick medullated fibres ; apparently it is not found in the normal 

 subject, but Kaes has recognised it twice in the brains of Epileptics'. 



Apart from Bechterew's line, the lower part of the supraradiary layer contains a varying 

 number of long, horizontally-directed, coarse fibres, which pertain to the association system of 

 Meynert. 



Rudlntions of Meynert. 



The radiary fasciculi, constituting the cortical portion of Meynert's projection system, 

 stand out so distinctly in sections stained for medullated nerve fibres that there is no possi- 

 bility of confusing them with anything else, hence their nomenclature remains simple. 



An analysis of their composition proves that they contain three varieties of fibres, viz. 

 large medullated ones with even contours, coarse varicose fibres and varicose fibrils ; and the 

 relative proportion of these varies in different parts of the hemisphere, as does also the 

 stoutness of the individual bundles; and these variations seem to bear a relation to the wealth 

 of representation of large pyramidal cells, the axis cylinders of which descend in the radiations. 



We have Kaes' authority for the statement that the radiations are more numerous in 

 some parts of the hemisphere than in others, but my observations have led me to believe 

 that the difference is insignificant and of minor importance. 



One constantly finds that the radiations are much shorter and generally more slender in 

 the cortex lining sulci than in that on the free surface, and as Wundt showed they are 

 entirely wanting in the sulci of the brains of some of the lower animals. 



Interradiary Plexus. 



This designation, for which we are indebted to Edinger, is applied to an extremely 

 intricate and dense plexus of fibres, which exists in the spaces between the radiary fasciculi, 



1 I have seen a modified line of Bechterew iu what I take to be the visual cortex of the Pig. 



