1905.] 



Cord of the Macaque Monkey. 



115 



(b) Eatio dorsal columns (P) (Chart K TaWe vm) 



grey substance (G) 



The curve (P) representing the ratio dorsal columns c ^g> erg f rom tna ^ f 



grey substance 



the ventro-lateral columns (A) in the total fall being much less pronounced. 



The ratio starting as only slightly more than 1:1 in the first lumbar 

 region falls gradually, and is less than 1 : 1 in the second lumbar region, 

 and throughout the remainder of the cord. Through the first three sacral 

 regions the ratio is approximately the same. The grey substance being taken 

 as unity, the index of the fall from the first lumbar to the third coccy- 

 geal region is only 0"95, the principal decrease occurring in the lumbar 

 regions (0 - 82) and chiefly in those of the first five lumbar nerves. 



(c) Eatio ventro-lateral columns (A) Chart ^ ^ vm 



grey substance (Gr) 



, A s . v ,. ,. ventro-lateral columns ■, , . ., 



Ihe curve (A) indicating the ratio resembles m its 



grey substance 



in ,. .i /-ixrx -, ,• ,• total white substance 



general configuration the curve ( W ) denoting the ratio 



grey substance 



The ratio decreases rapidly from the first to the seventh lumbar region, the 

 decrease being most marked in the regions of the first five lumbar nerves. 

 In the seventh lumbar and first and second sacral regions the ratio is almost 

 the same. A slight decrease from the third sacral to the first coccygeal 

 region is followed by a slight increase in the lower coccygeal regions, the 

 ratio being approximately the same in the third coccygeal as in the seventh 

 lumbar region. 



a 14-t, i i-t i i t . . i, . ventro-lateral columns • , 



Although the absolute fall m the ratio is much 



grey substance 



greater than that in the ratio dorsal columns re ] atively the variation of 



grey substance 



the latter is considerably greater. 



This is seen in Chart X, where the ordinates indicate the relative values 



of the ratios, when the ratio for the first lumbar region is in each case 



taken as 10 (Table IX). 



