Chap. XVI.] 



THE SPINAL CORD. 



These various divisions can be traced from the 

 medullata obloiigata into the cervical, and more or 

 less into 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 stroma 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- 

 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 chiefly in a longitudinal direction, 

 in the grey matter they extend uniformly in all 

 directions, and in the septa between the columns they 

 extend for the most part radially. 



(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 



Fig. 84. From a Transverse Section 

 through a most Peripheral Part of 

 the White Matter of the Cord. 



c, A special peripheral condensation of 

 neuroglia; w, white matter with the 

 medullated nerve-fibres shown in 

 cross section, :iud acuroglia between 

 them. (Atlas.) 



