104 Miss M. P. FitzGerald. The Lumbosacral-coccygeal [June 17, 





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Chart III. — Curves showing the Percentage Value of the Grey and of the White 

 Substance in the Cross-section of the Cord (Table VI). 



The total area of each cross-section of the cord = 100. The ordinates denote per- 

 centage value, the abscissae the length of the cord in centimetres measured from the 

 uppermost section of the first lumbar region. The numbers (I, II, III, etc.) mark 

 approximately the cephalic end of the region of each pair of spinal nerves. 



Percentage of grey substance G, dotted line. 



Percentage of white substance ... W, thin continuous line. 



The percentage of grey substance in the cross-section of the cord (Chart III, 

 (jr, Table VI) rises almost continuously from ca. 20 per cent, in the first 

 lumbar region to 52 per cent, in the first coccygeal (maximum 52'9 per cent.). 

 A slight fall in the percentage in the second coccygeal region is followed by 

 a marked fall to 47 per cent, in the third coccygeal. 



The percentage of white substance, on the other hand, falls almost con- 

 tinuously from ca. 80 per cent, in the first lumbar region to ca. 47 per cent, 

 in the first coccygeal ; and corresponding to the fall in percentage of grey 

 substance, a slight rise in the second coccygeal is followed by a rapid rise 

 to 51 per cent, in the third coccygeal region. 



Thus, between the regions of the first lumbar and the first coccygeal nerve, 

 there is an absolute rise in percentage of grey substance and a fall in that 

 of white substance of 32. 



