208 ; EDWARD HORNE CRAIGIE 
A comparison of the groups according to locality has also 
been made, the average of the results for the four Toronto 
animals being compared with that for the four specimens from 
the standard colony of The Wistar Institute. The differences 
Vascularity 
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Corticdl laminae 
Fig. 5 Graphs showing in the same way as in figure 4 the relative vascularity 
of the cerebral cortex in rats from two different localities. Toronto @. The 
Wistar Institute +. 
between these groups are illustrated graphically in figure 5. 
Here again, the difference is a little more decided than in the 
lower parts, though less definite than that between the sexes. 
In this case, however, the suspected specimen (R. 56) belongs 
‘to the group which is richer in most layers (the group from The 
5000 
