STRUCTURE OF THE WHITE COLUMNS OF THE SPINAL CORD. 337 



viously here in place as a provision against the various 

 movements and extensions to which the spinal cord, on account 

 of the mobility of the vertebral column, is exposed. 



I have not been able to determine satisfactorily the occurrence 

 of division of the nerve fibres in the white substance, though 

 other observers* have been more successful. 



The diameter of the nerve fibres of the white substance is 

 not constant, as may best be shown by a comparison of the 

 diameter of the fibres in various regions of the spinal cord. 

 The thickest nerve fibres, having a diameter of 0'012 to 0'020 

 of a millimeter, are found in that portion of the anterior 

 columns which bounds the sulcus longitudinalis anterior. The 

 difference in the diameter of the fibres of any given area is 

 here also less marked. On the other hand, in the lateral 

 columns nerve fibres may be found in one and the same area, 

 of which some have a diameter of 0'014 to O'OIS of a milli- 

 meter, whilst others do not exceed 0*004, 0*006, and O'OOS of a 

 millimeter. The thick fibres are more numerous in the peri- 

 pheric portion of the columns, the finer ones in the more 

 internal parts near the grey matter. The size of the fibres in 

 the posterior columns have a certain definite relation to one 

 another, becoming thicker the more anteriorly, i.e., the nearer 

 the posterior grey commissure they lie. In the latter region 

 the fibres of the posterior columns have a diameter of 0'014 

 of a millimeter, whilst those situated more posteriorly, which 

 become progressively finer, diminish to 0'005 and O'OOS of a 

 millimeter. A fasciculus of fibres*)" that on section presents the 

 appearance of a wedge, the point of which is directed forwards 

 and inwards, and the thicker part backwards (see fig. 218, A), 



* O. Deiters, Untersuchungen uber Gehirn und Ruckeivmark, herausge- 

 geben von Max Schultze, 1868, p. 110. "Researches on the Brain and 

 Spinal Cord," edited by Max Schultze. 



f This was first described by Burdach as the slender fasciculus of the 

 posterior column, and named subsequently by Kolliker, GolTs "fasciculus 

 cuneatus," which appears to me to be a not very well selected name, since 

 Burdach divided the posterior column of the cervical portion of the spinal 

 cord into the slender fasciculus (i.e., into Goll's "fasciculus cuneatus") 

 and the fasciculus cuneatus, under which term he included the lateral por- 

 tion of the posterior column of the cervical spinal cord after it had given 

 off the median slender fasciculus. 



VOL. II. Z 



