1905.] 



Cord of the Macaque Monkey. 



123 



The decrease in section area is very slight between the fifth and the middle 

 portion of the seventh lumbar region. It is accentuated between the 

 seventh lumbar (middle portion) and the third sacral region, and, with the 

 exception of being marked between the first and second coccygeal regions, is 

 continued in a regular manner to the end of the cord. 



In the first coccygeal region the section area of the dorsal horns (D) is 

 almost equal to that of the ventral horns (V), and is slightly greater in the 

 second and third coccygeal regions. 



(b) Section Area of the Ventral Horns. 



The section area of the ventral horns (Chart XIII V, Table XIII) 

 increases from the first to the lower portion of the fifth lumbar region, 

 where the maximum (5 - 68 sq. mm.) is reached. The maximum is thus found 

 in the same region (VL) as the maximum section areas of the dorsal 

 horns (D), and of the grey substance as a whole (G). 



The section area of the ventral horns (V) decreases from the fifth lumbar 

 region to the end of the cord. 



The increase in section area is very gradual from the first to the lower 

 part of the third lumbar region, but becomes very marked between the 

 latter and the lower part of the fifth lumbar region, three-fifths of the whole 

 increase occurring here. The most rapid increase is between the third and 

 fourth and in the fourth lumbar resion. Throughout the fifth lumbar 

 the section area is nearly four times as great as that in the first lumbar 

 region. 



The decrease in section area is more rapid than the increase, and is very 

 marked between the lower portion of the fifth and that of the sixth lumbar 

 region. From the seventh lumbar region to the end of the cord, the decrease 

 continues in a more regular manner and is least marked between the third 

 sacral and second coccygeal regions. 



The section area of the ventral horns (V) in the seventh lumbar region 

 (ca. 3 sq. mm.) is much the same as that in the third lumbar region, and 

 in the second sacral (ca. To sq. mm.) it is much the same as in the first 

 lumbar region. 



