1905.] 



Cord of the Macaque Monkey. 



131 



It will be seen that whereas the ratio vential hoins (V) — taken as 



total area or cross-section 



unity in the first lumbar region increases rapidly to the sixth lumbar, it 



decreases at the first sacral, remains constant at the second, falls slightly 



from this to the fourth sacral, and while rising again in the first coccygeal 



region, subsequently falls rapidly to the third coccygeal. 



On the other hand, the value of the ratio dorsal horns (D) — _ — taken 



total area of cross- section 



as unity in the first lumbar region increases slightly in the second lumbar, 



but falls and has practically the same value in the third and fourth lumbar 



regions as in the first. It then increases rapidly from the fifth lumbar 



region to the end of the cord. 



In regarding the curves together it will be observed that the two ratios 

 V and D, bear roughly the same proportion to each other in the second 

 sacral region that they do in the first lumbar. 



A further noteworthy point is that while the dorsal and ventral horns 

 each constitute, relatively, a much larger portion of the total area of the 

 cross-section of the cord in the third coccygeal than in the first lumbar 

 region, the increase is much more important in the case of the dorsal 

 horns (D). 



Table XVII. — Eelative Values of the Eatios 

 Ventral Horns 



Dorsal Horns 



Area of Cross-section of Cord 

 Table XVI) is in each case taken as unity (Chart XVI) 



Area of Cross-section of Cord 

 The ratio in the I Lumbar region (vide 



Region of cord. 



Dorsal horns. 



Ventral horns. 



Lumbar — 









1-0 



1-0 



II 



1-17 



1-27 



Ill 



1 -04 



1 -63 



IV 



0-99 



2 -22 



V ; 



1-13 



2-54 



VI 



1 -46 



2-61 



VII 



1 -94 



2-45 



Sacral — 







I 



2-23 



2-31 



II 



2-28 



2 -30 



Ill 



2-42 



2 -26 



IV 



2-68 



2 -22 



Coccygeal — 







I 



2-95 



2-31 



II 



3-05 



2 13 



Ill 



3-24 



1-74 



