108 Miss M. P. FitzGerald. The Lumbosacral-coccygeal [June 17, 



The rise, beginning in the middle portion of the first coccygeal, is continued 

 through the second and third coccygeal regions. The percentage attained in 

 the third coccygeal is equal to that in the fifth and sixth lumbar regions. 



Hence it is seen that of the total fall of ca. 32 per cent, occurring in the 

 percentage of the white substance (W) to the cross-sections of the cord, 

 between the first lumbar and first coccygeal regions (upper portions), 11 is due 

 to the fall in percentage of the dorsal columns (P), and 21 to that of the 

 ventro-lateral columns (A), and that although the percentage value of both 

 components of the white substance falls rapidly between the first and seventh 

 lumbar regions, it is within these limits that the fall of the ventro-lateral 

 columns so far exceeds that of the dorsal columns. 



A further interesting point is the lack of correspondence between the fall 

 of the ventro-lateral columns and that of the dorsal columns in the different 

 nerve regions. This is especially noticeable between the first and seventh 

 lumbar regions. 



The comparatively slight rise seen in the percentage curve of the total 

 white substance (W, Chart III) from the first to the third coccygeal region is 

 accounted for by the continuance of the fall in percentage of the dorsal 

 columns counteracting the rise in that of the ventro-lateral columns. The rise 

 in the ventro-lateral columns (A) in the third coccygeal region is, however, 

 more marked than the fall in the dorsal columns. 



Comparison Between the Section Area and the Percentage Value 

 of the Component Parts of the Corel. 



For the purpose of comparing the section area with the percentage value 

 of any one component part of the cord, the mean figures of both have been 

 taken in the region of each spinal nerve (see Tables II to VII) and the curves 

 plotted in the same chart. 



Both the sectional area (G) and the percentage value (g) of the grey 

 substance increase from the first to the fifth lumbar region. From the fifth 

 lumbar to the third coccygeal region the sectional area decreases, whereas 

 the percentage value increases to the first coccygeal, but decreases slightly 

 in the second, and to a somewhat greater extent in the third coccygeal 

 region. 



