THE NERVOUS SYSTEM. 



1 .33 



striped. As they proceed they become more homogeneous, 

 and at the same time divide into very numerous and extremely 



slender branches, so that at last, from each process a large 

 bundle of very fine filaments, having a diameter, in the finest, 

 of scarcely , 0002' / ', is produced. A portion of these fibrils 

 penetrate more horizontally into the grey layer, although most 

 of them stretch directly outwards, and appear to extend nearly 

 to the outer surface of the grey layer. That they extend 

 very far is certain, for in preparations made with chromic acid, 

 I have isolated some measuring 015 — 02" ', which were 

 still not the finest ; and in successful perpendicular sections 

 through the cortical layers of the convolutions, their principal 

 branches appear as parallel, slightly undulating fibres in 

 close contiguity, extending through more than two thirds, or 

 even three fourths, of the grey layer, to which they give a 

 peculiar striated aspect. Whilst the principal prolongations 

 of the processes arc, in this way, continued through the grey 

 layer, they give off their branches at acute or right angles, 

 whence not unfrequently a second striation is produced, 

 crossing the one just described at a greater or less angle. 

 In the innermost portion of the grey layer, among the large 



Fig. 148. Large cells of the grey layer of the cortical substance of the human 

 cerebellum, x 350 diam. 



I. 



28 



