854 MR HAROLD AXEL HAIG ON THE 
C. Lumbar region. (Text-fig. 3.) 
The three main subdivisions of each lateral crescent of grey matter can be dis- 
tinguished, viz. posterior, intermedio-lateral, and anterior horns. 
A few nerve-cells are present about the middle of the posterior horn, and a well- 
marked group is to be seen at the base of the posterior horn (Clarke’s column). 
Groups also occur at the tip of the intermedio-lateral horn, and to the number of three 
in the anterior horn, these being very obvious and the component cells very large. 
Fic. 3.—A transverse section of the spinal cord (lumbar region). Lettering as in figs. 1 and 2, except :— 
d.m. Dura mater, 
p.r.b. Posterior root- bundles. 
a.7r.b. Anterior root-bundles. 
n. Bundles of the cauda equina. 
v. Large branches of the vertebral vessels. 
The posterior or grey commissure is wide, and the anterior white commissure is 
relatively broad in the antero-posterior direction: the central canal appears as a 
four-sided space lined by an ependyma possessing an internal layer of ciliated 
epithelium. | 
The posterior root-bundles are very large and number three or four on each side 
posteriorly, lying between the dura mater and the pial investment of the cord; the 
anterior bundles are two in number on each side antero-laterally. 
Of the white matter, the lateral columns are of fairly wide extent, as also are the 
anterior columns; there is no marked distinction between Goll’s and Burdach’s columns 
posteriorly, although a small pial septum does show the superficial division. 
