xi] Ti/jK' of Cell Lamination 253 



This change iii tin- line of Hail larger has proved a useful corrective in regional 

 differentiation. 



Radiations uf Meynert. 



The fasciculi are all slender and chiefly composed of thin wavy fibrils. In the anterior 

 insular region a coarse medullated fibre is never seen except along the confines of the 

 orbital operculum, and even medium-sized fibres are uncommon, but posteriorly, particularly 

 in the vicinity of the transverse temporal gyri, gross fibres occasionally appear and give 

 prominence to the bundles. 



The bundles tend to pierce the line of Baillarger and are infinitely longer over the 

 crowns of the different gyri than in the intervening flat sulcal portions. 



Interradiary Ple.i-us and Association tit/stem. 



The general weakness in fibre wealth extends to the radiary zone, and is more pronounced 

 anteriorly than posteriorly: for whereas in the latter position an appreciable number of 

 long, medium-sized, association fibres traverse the interradiary spaces, in front of the central 

 sulcus such fibres are uncommon and the plexus is almost entirely composed of delicate, 

 wavv, varicose fibrils. 



White Projection. 



A study of the white substance in over-differentiated specimens is not void of interest, 

 because it can be distinctly proved that while all that lying beneath the limiting sulci is 

 richly supplied with fibres of large calibre, such fibres gradually dwindle away as the centre 

 of the insula is approached. 



On the important question of the connection between the claustrum and the cortex of 

 the insula my sections afford little information, only in a few instances have I been able 

 to trace large coupling fibres. 



In general terms therefore we may describe the fibre representation of the insula as 

 poor, and the topical variations as being not particularly interesting. 



TYPE OF CELL LAMINATION. (Plate XXV, fig. 2.) 

 The two types of cell lamination which I would describe are as follows: 



TYPE No. 1. 

 The type which corresponds in distribution to the anterior fibre area. 



Plexiform Layer. 

 This presents no features of interest. 



l.ai/er of Small Pyramidal Cells. 



This lamina is not so richly endowed with elements as it is in other parts of 

 the brain. 



