chap, xvi.] THE SPINAL CORD. 135 



in a former chapter. The medullated nerve-fibres, 

 or rather the matrix of their medullary sheath, con- 

 tains neurokeratiii. The nerve-fibres of the white 

 matter run chiefly 

 in a longitudinal 

 direction, -and they 

 are separated from 

 one another by the 

 neuroglia. Here and i^^^tj 

 there in the columns ?^5 ? \ 

 of white matter are @^' ^>^^ 3 .V , 



seen connective tis- '"*$ 

 sue septa with ves- r = - b c J /J 



sels, by which the 



nerve - fibres are p . g ^_ Ytom a " Transverse Section 

 grouped more or through the White Matter of the Cord. 



less distinctlv in Showing the transversely-cut medullated nerve- 

 .i&uiii,ujr fibres, the ueuroglia between them .with two 



divisions. branched neuroglia cells. (Atlas.) 



174. Although 



most of the nerve-fibres constituting the columns of 

 white matter are of a longitudinal direction i.e., 

 passing upwards or downwards between the grey 

 matter of the cord on the one hand, and the brain and 

 medulla oblongata on the other there are nevertheless 

 a good many nerve-fibres and groups of nerve-fibres 

 which have an oblique or even horizontal course. 



Thus : (1) The anterior median fissure does not reach 

 the anterior grey commissure, for between its bottom 

 and the latter there is the white commissure. This 

 consists of bundles of medullated nerve-fibres passing 

 in a horizontal or slightly oblique manner between the 

 grey matter of the anterior horn of one side, and the 

 anterior white column of the opposite side (Fig. 82,0). 



(2) Numerous medullated fibres are derived from 

 the grey matter, and they pass in a horizontal or 

 oblique direction into the white matter, especially in 

 considerable numbers into that of the lateral columns. 



