STRUCTURE OF THE WHITE COLUMNS OF THE SPINAL CORD. 339 



columns, so far as it is possible to estimate from transverse 

 sections, contain about an equal proportion of both, except that 

 in that part of the lateral columns which immediately surrounds 



Fig. 221. 



7 



Fig. 221. Transverse section of a posterior half of the spinal cord 

 of Man, at the level of the lumbar enlargement, treated with double 

 chloride of gold and potassium, and exhibiting extraordinarily distinct 

 fibrillation in the grey substance of the posterior cornu. Magnified 

 50 diameters, a, Posterior column ; 6, lateral column ; c, fibrillation 

 of the posterior cornu ; d, substantia gelatinosa ; e, roots of posterior 

 spinal nerve, which before their entrance into the grey substance 

 ascend, and perhaps also descend for a short distance, in the posterior 

 column ; </, horizontal fibres passing from the posterior cornu into the 

 posterior column, and from the posterior column into the posterior 

 cornu ; /i, fasciculi situated in front of the subatantia gelatinosa, and 

 ascending in the posterior cornu. 



the grey substance the connective tissue appears to be more 

 abundant. The posterior columns, again, are somewhat richer 



32 





