XXXl] SPINAL CORD 239 



column forms in the upper and middle region an area with its 

 long axis at right angles to the posterior column. 



In the lumbar swelling a sharp angle almost a right angle- 

 is presented by the head of the posterior cornu towards the 

 posterior column (this is not very different from some sections 

 of the human cord). 



6. Section of human cord (lumbar) with the 

 medulla of the fibres stained (cp. 7). Note 



The great number of small medullated nerve fibres 

 in the grey substance, except in the substantia gelati- 

 nosa of the head of the posterior cornu, and around the 

 central canal; the crossing small medullated fibres in 

 the grey commissure ; the large medullated fibres 

 crossing in the white commissure (from the anterior 

 cornu of one side to the anterior column of the 

 opposite); the fibres of the posterior root partly 

 curving into Burdach's column, partly running in small 

 bundles through the substantia gelatinosa ; the bundles 

 of fibres from the deep part of Burdach's column 

 curving into the grey substance. 



7. Sections of lumbar region of spinal cord (chrome alum 

 mixture, cut frozen). Place the sections : 



in 1 p.c. osmic acid for about half an hour, and wash with 

 water ; 



in 5 p.c. pyrogallic acid for about half an hour, and wash 

 with water ; 



in '25 p.c. permanganate of potash for a few seconds to a 

 minute or two, according to the rate of decolourization, and wash 

 with water ; 



in 1 p.c. oxalic acid for one or two minutes and wash with 

 water. 



Dehydrate and mount in balsam. Note the large number of 

 medullated fibres in the grey matter. The grey substance apart 

 from its medullated fibres should be of a light grey tint. 



