1905.] 



Cord of the Macaque Monkey. 



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Chart IV. — Curves showing the Percentage Value of the Grey Substance and of the 

 Dorsal and Ventro-lateral "White Columns in the Cross-section of the Cord 

 (Tables VI, VII). 



The area of each cross-section of the cord = 100. The ordiuates denote percentage 

 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 dorsal white columns P, broken line. 



Percentage of ventro-lateral white columns ... A, line and dot. 



The curve (A, Chart IV) shows alternate periods of falling value and a 

 condition of equality or slight rise, especially between the first and seventh 

 lumbar regions.* 



Speaking generally, the fall in percentage is most rapid between the upper 

 portion of the first lumbar and the lower portion of the fifth lumbar region. 

 Taking the individual nerve regions, the most conspicuous fall occurs 

 between the lower portion of the region of the third and that of the fifth- 

 lumbar nerve, it being most marked in the fifth. 



The percentage value of the ventro-lateral columns (A) is equal to that of 

 the grey substance (G) in the sixth lumbar region. 



From the seventh lumbar to the third sacral region (upper portions) the- 

 percentage is practically the same. 



This may indicate a segmental factor. 



