Chap. XVI.] 



THE SPINAL CORD. 



133 



These various divisions can be traced from the 

 medullata oblongata into the cervical, and a greater 

 or smaller portion of the dorsal part of the cord, but 

 farther down most of them are lost as separate tracts, 

 except the fasciculus of Turk. 



171. The ground substance (Fig. 84) of both 

 the white and grey matter i.e., the substance in 

 which nerve-fibres, 

 nerve cells, and blood- 

 vessels are embedded-^- 

 is a peculiar kind of con- 

 nective tissue, which 

 is called by Virchow 

 neuroglia and by Kol- 

 liker supporting tissue. 

 It consists of three dif- 

 ferent kinds of ele- 

 ments : (a) a homoge- 

 neous transparent semi- 



A special peripheral' condensation of 

 neurogliA; ;<>, white matter with the 

 inedullatect nerve-Iihres shown in 

 cross section, and neuroglia between 

 them. (Atlas.) 



Fig. 84. From a Transverse Sectiou 

 through a most Peripheral Part of 

 the White Matter of the Cord. 



fluid matrix, which in 

 hardened sections ap- 

 pears more or less gran- 

 ular; (b) a network of 



very delicate fibrils neuroglia fibrils which are 

 similar in some respects, but not quite identical with 

 elastic fibres. 



In the columns of the white matter the fibrils extend 

 pre-eminently in a longitudinal direction, in the grey 

 matter they extend uniformly in all directions, and in 

 the septa between the columns they extend chiefly in 

 the direction vertical to the long axis of the cord. 



(c) Small branched nucleated cells intimately 

 woven into the network of neuroglia fibrils. These 

 cells are the neuroglia cells. The greater the amount 

 of neuroglia in a particular part of the white or grey 

 matter the more numerous are these three elements. 



172. In both the white and grey matter the 



