1905.] 



Cord of the Macaque Monkey. 



121 



ventral horns (V), with its marked rise and fall, resembles in every way the 

 curve illustrating the section area of the grey substance as a whole. 



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ILiunhar IT JH ' JV V VI VII TSacr.R BI IV ICce^E >ffl 



Chart XIII. — Curves showing the Section Areas of the Grey Substance and of the 

 Dorsal and the Ventral Horns of the same (Tables II, XII, XIII). 



The ordinates denote section area in square millimetres, and the abscissae the length of 

 the cord in centimetres measured from the uppermost section of the first lumbar region. 

 The Roman figures mark approximately the cephalic end of the region of each pair of 

 spinal nerves. 



Grey substance as a whole...... G, dotted line. 



Dorsal horns D, interrupted line and cross. 



Ventral horns V, line, dot, and cross. 



(a) Section Area of the Dorsal Horns. 



The section area of the dorsal horns (Chart XIII D, Table XII) increases 

 from the first to the fifth lumbar region, and decreases from the lower 

 portion of the fifth to the end of the cord. The actual increase between the 

 first and fifth lumbar regions amounts to - 87 sq. mm. (1 - 1 — 1*97 sq. mm.). 

 The section area at its maximum (V L, lower) is thus almost twice as great as 

 in the first lumbar region. 



It will be observed that the maximum is reached in the same region, as 

 the maximum section area of the grey substance (G-). 



Both the increase and decrease in the section area of the dorsal horns take 

 place gradually, but the decrease is more rapid than the increase. The 

 section area varies very little in the first lumbar region, it becomes rather 



