* 



340 THE SPINAL CORD, BY J. GERLACH. 



in the same tissue than the anterior and lateral columns ; this 

 is especially the case with the median segment of the posterior 

 columns of the cervical region, i.e., the slender columns of 

 Burdach and the fasciculi cuneati of Goll, which hence present 

 a redder appearance in preparations stained with carmine than 

 the rest of the white substance. 



In regard to the direction pursued by the nerve fibres in the 

 white substance of the cord, some are vertical, some horizontal, 

 and others again oblique. 



The vertical fibres are by far the most abundant, and con- 

 stitute the chief constituent of the several columns of the cord 

 they assume a parallel arrangement, and, united into fasciculi 

 of various sizes, ascend to the medulla oblongata. The dif- 

 ferent fasciculi are separated from each other by connective- 

 tissue septa, which are seen in transverse sections to proceed 

 from the inner layer of the pia mater. 



A superimposition and even an interweaving of their bands 

 is certainly not unfrequently seen in longitudinal section ; but 

 in my opinion these appearances in the cord below the medulla 

 oblongata are chiefly due to the extraordinary difficulty that is 

 experienced in making a perfectly vertical longitudinal section 

 of the cord. By far the greater number of those sections that 

 are usually considered to be vertical are really more or less 

 oblique, and in such it is obviously not surprising that, instead 

 @f simple apposition there should be a certain amount of 

 super-imposition or even interweaving of the fasciculi. I have 

 only been able to discover a true interweaving of fasciculi 

 with certainty, and the passage of the fibres of one fasci- 

 culus into an adjoining one, in the median portion of the 

 lateral cords. 



Horizontal fibres occur in the following regions of the white 

 substance of the cord : 



1. In the anterior white commissure, where the direction 

 ' they pursue may be easily traced in transverse sections, pre- 

 senting the appearance of a beautiful decussation (fig. 217, /, 

 and fig. 226, i\ though this is by no means a proof of the decus- 

 sation of the anterior columns ; on the contrary, according to 

 my observations, all the horizontal fibres of the anterior white 

 commissure that pass to the anterior column of the opposite 



