200 EDWARD HORNE CRAIGIE 
average vascularity of the five layers is the same in the occipital 
and temporal regions, and it is very little less in the praecentral 
region. The parietal region is distinctly the richest, while the 
insular is much the poorest. 
With regard to individual variation, it is noticeable that the 
same individuals tend to give rather high or rather low results 
in all the cortical areas, but the values obtained in the lower, 
subcortical centers of these individuals were not always similarly 
high or low. These differences are reflected in the ratios of the 
cortical values to those for the ventral white column and the 
ventral gray cornu of the cord, which have been set down in a 
detailed table, not published, from which table 1 has been con- 
TABLE 2 
Average vascularity of five areas of the cerebral cortex. (The averages of the values 
shown for the five laminae of each area in the second last column of table 1) 
CORTICAL AREA MPER 5 X 1892 X 200 ¢c.u 
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densed, and which show considerable fluctuation. The indi- 
vidual ratios referred to have all been averaged, and the results 
are found to correspond so satisfactorily with the ratios of the 
average readings, shown in table 3, that it is considered sufficient 
to publish the latter. 
The averages for the various layers of each area, as recorded 
in next to the last column of the first table, are represented 
graphically in figure 3, which illustrates the relation between the 
different regions as well as that between the five laminae in each. 
It will be observed that the relative vascularity of the five 
laminae in the various areas studied is fairly constant, not only 
as regards the averages, but even, though to a smaller extent, 
in the different individuals, as shown in table 1. The greatest 
irregularity which appears is in the case of R.56, in which the 
