J. F. Tocher 
197 
the proper data, it is possible that the positive association may become a 
significantly positive one. Since excess of dai-k eyes in the Scottish population 
has been here shown to occur in densely populated parts, the dark-eyed class here 
at any rate belongs largely to the poorer section of the population. But the lower 
classes are more fertile than the upper classes. If the dark-eyed portion of the 
lower classes is more fertile than the remaining portion, and if a selective death 
rate does not operate against the dark-eyed, this would go far to explain the 
excess of dark eyes in densely populated parts not explainable by the presence 
of foreigners or of migrants from contiguous rural areas. 
VIII. Relationships between Pigmentation and Physical and Mental Defects. 
In a recent memoir*, already referred to, it was shown, using the division analysis 
results of the present data, that cases of insanity were in excess of the mean in 
areas where there was an excess of light eyes in the population. The enquiry has 
been extended in order to note whether excess of any particular hair colour or eye 
colour is associated with physical or mental defects such as blindness, deafness and 
imbecility. The following results were obtained, the results for insanity cases 
being included. The figures used in comparing the results were taken from the 
Census Report 1901, 
TABLE XLII. 
Relationships between Pigmentation and certain Defects or Affections. 
Hair Colour. 
Defect or Affection 
Fair 
Red 
Medium 
Dark 
Jet Black 
?• 
r 
r 
r 
E(r=t,) 
r 
■E(r=0) 
r 
r 
r 
r 
E{r=o) 
Insanity 
-•024 
- •lO 
- -582 
-2^28 
-•128 
- •SO 
•340 
1 -33 
•084 
•33 
Imbecility or Feeble- 
mindedness 
•608 
2-38 
-•213 
- ^83 
- ^942 
-3^69 
•672 
2-63 
•893 
3 •.50 
Blindness 
•56.^) 
2^22 
•006 
•02 
-•868 
-3^40 
•546 
2-14 
•885 
3^47 
Deafness 
•300 
ri8 
•054 
•21 
-•707 
-2-77 
•572 
2^24 
•789 
3-10 
Deaf and Dumb 
•126 
■49 
•148 
•58 
- '136 
- -fy-i 
-•026 
- •lO 
•273 
1-07 
Eye Colour. 
Defect or Affection 
Blue 
Light 
Medium 
Dark 
r 
r 
r 
r 
r 
r 
r 
r 
•E(r=o) 
ii()-=o) 
-E(,-=o) 
Insanity 
- -072 
- -28 
•695 
2-73 
- ^322 
-1-26 
- -482 
- r89 
Imbecility or Feeble- 
mindedness 
•841 
3 30 
-•253 
•99 
- -753 
-2^96 
- -647 
-2^15 
Blindness 
•951 
3 73 
- ^464 
r82 
-•775 
-3^04 
-•442 
- 1 -73 
Deafness 
•819 
3^21 
- ^386 
rsi 
- -609 
-2 39 
- ^489 
-1^92 
Deaf and Dumb 
•309 
1^21 
- ^453 
1-78 
- •lis 
- -46 
•149 
•58 
* Biometrika, Vol. v. p. 342. 
