166 



THE CEREBRAL HEMISPHERES. 



in front of the occipital lobe and connects the inferior parietal lobule with the 

 fusiform lobule (/j9.). 



(/) The fornix. This (fo.*), by means of its continuation, the fimbria (fi-\ 

 connects the hippocampal region of the limbic lobe with the corpus albicans, which 

 again is connected through the bundle of Vicq d'Azyr (v.d'A.) with the thalamus 



Fig. 114. DIAGRAM OF THK ASSOCIATION-FIBKES OF THE CEREBRAL HEMISPHERE. 

 (E. A. S., after Meynert.) 



s., short association-fibres, connecting adjacent gyri ; f.l.s., fasciculus longitudinalis superior; ci. , 

 cingulum ; f.p., fasciculus perpendicularis ; f.l.i., fasciculus longitudinalis inferior ; f.u., fasciculus 

 uneinatus ; fo., fornix ; fi., fimbria ; v.d'A., bundle of Vicq d'Azyr. 



opticus. The course and relations of the fornix have already been described 

 (pp. 129, 158). 



The arrangement of the fibres in the white matter has been studied by H. Sachs, who finds 

 that the fibres in the occipital lobe (the only part as yet fully investigated by him) are arranged 

 in four layers or series, from within out, as follows : 1. Those which are prolonged from the 

 corpus callosum (forceps major), which occupy the central parts nearest the ventricle. 2. Next 

 to these a layer composed of projection-fibres, passing to the internal capsule. They are finer 

 than the callosal fibres. 3. Another layer of larger fibres which surrounds the projection-layer, 

 and is composed of long association-fibres. 4. A layer of short association-fibres, nearest the 

 cortex. It will, of course, be understood that the peripheral layers are constantly pierced by 

 the fibres which are passing from the cortex to join the more centrally-situated layers.] 



STRUCTURE OP THE! GREY MATTER,. 



The grey matter on the convoluted surface of the cerebrum forms a continuous 

 layer indistinctly divided into two or three strata by interposed thin layers of paler 

 substance. 



In examining a section macroscopically from without inwards (fig. 115, 1), we 

 meet with 1. A thin coating of white matter situated on the surface, which on a 

 section appears as a faint white line, bounding the grey surface externally. This 

 superficial white layer is not equally thick over all parts of the cortical substance, 

 but becomes thicker as it approaches the borders of the convoluted surface ; it is 



