188 Pigmentation Survey of School Children in Scotland 
was found to be r = •9125 from the accompanying table (Table XXXVI.). Diagram 
XIX. shows graphically the connection between density and other characteristics 
in the population. 
Thus the association is very high. It will be of interest now to note what 
relationship, if any, exists between colour and the death rate. The following results 
were obtained (Table XXXVII.). 
TABLE XXXVIL 
Correlation between Death Rate and Pigmentation. 
?■ 
r 
Hair: 
Fair 
-•806 
-3^16 
Eed 
- -347 
- 1-36 
Medium 
•567 
2-23 
Dark 
■064 
•25 
Jet Black . . . 
-•252 
- ^99 
Eyes : 
Bhie 
- -488 
-r9i 
Light 
•226 
•89 
Medium 
•284 
1-11 
Dark 
•410 
1-61 
This result, a positive correlation between the death rate and medium hair, and 
another between death rate and dark eyes, was to be expected, since density is 
similarly associated with colour. The denser the population is the greater is the 
death rate; the denser the population is the greater is the excess of medium 
hair ; therefore the greater the excess of medium hair, the greater the death rate. 
(1) Is it to be concluded that medium haired or dark-eyed people are less virile 
and cannot stand the strain of city life ? (2) Must one say that the blue-eyed fair- 
haired classes have been all killed out in densely populated areas since they have 
less resistive power and it is now the turn of the darker section of the population 
who now presumably show greater mortality ? (3) Or must it be said that the 
conditions of town life are such as to cause a larger section of the fair-haired class 
to become so much more sensibly darker in towns than in rural districts so as to 
be classed as medium or brown ? There is a darkening in the fair-haired class 
with age ; that much is well known. Is the darkening more intensely operative in 
towns, and why ? (4) If not, can any explanation be offered as to why medium 
hair colour is associated positively with density and thus with the death rate — why 
a proportion of medium haired persons much above the average live in more densely 
populated parts (and are thus of the poorer class) where mortality is higher than 
the average ? An attempt will now be made to answer these questions so far as 
they can be answered, seriatim. 
VI. The probable Cause of the Association of the Medium or Brown Haired 
Class tuith Density of Popidation. It cannot be said from the data of this survey 
