226 Pigmentation Survey of School Children in Scotland 
and a small class with jet black hair. This latter class constitutes only 1;^ per 
cent, of the total population. The girl population contains a higher proportion 
of the fair-haired class than the boy population, over 27 per cent, as against 
25 per cent. There is a correspondingly less proportion of the medium or brown- 
haired class in the girl population. The cause of this difference is not quite 
apparent. It should be remembered that the children surveyed are those of 
school age — a fairly wide range, from 6 to 18 — and that hair colour in children 
gets visibly darker as the children get older. If the children were classed according 
to age and their colour characters tabulated, it would be ascertained whether or 
not the difference was due to an earlier darkening in hair colour among the boy 
population, or whether the boy population was really significantly darker in hair 
colour from infancy than the girl population. From the results of observations 
of the physical characters generally of both sexes, a really significantly darker boy 
population from natural causes is improbable. It should moreover be remembered 
that, in determining hair colour, boys and girls are not judged exactly under 
the same conditions. Hair colour in girls is generally judged from long tresses. 
These are usually absent in boys, whose hair colour is judged from the shorter 
mass. Besides, girls' hair frequently shows extreme variety of tint from tip to 
root. Another possible explanation is the stimulus given to the increase of pigment 
by hair cutting in the boy population. This explanation requires verification 
from observations, (a) on a population of children in which the conditions are the 
same, and (^) on the adult population. 
The results of the observations on eye colour show that over 22 per cent, 
(nearly one-fourth) of the school children of Scotland have dark brown or dark 
eyes, and over three-fourths of the population possess blue, light or medium eyes. 
About 15 per cent, possess pure blue eyes, 30 per cent, light eyes, and about 
32 per cent, (nearly one-third of the population) possess eyes of the mixed type 
— the varieties classed as medium eyes. 
Comparing these general results with the results of similar surveys in foreign 
countries, it is seen that they differ markedly in many respects. In Northern 
Europe, between the same latitudes as Great Britain lies from Frankfurt, Prague 
and Cracow in the south to Christiania, Stockholm and St Petersburg in the 
north, one finds a heterogeneous population in which the fair-haired class pre- 
dominates. In Prussia alone, 72 per cent, or nearly three-fourths of the children 
are fair-haired. In Sweden, a similar proportion of the adults are fair-haired. In 
Schleswig, 80 per cent, of the children are fair-haired ; in Saxony, 69 per cent. 
Germany, south of Frankfurt and Coburg, is distinctly darker than the northern 
and larger portion. But even in South Germany the proportion of the fair-haired 
class far exceeds that found in Scotland. In Alsace and Lorraine the proportion 
is 47 per cent. ; in Baden 58 per cent. ; in Wiirtemberg 62 per cent. ; and in 
Bavaria 54 per cent. The difference in the distribution of eye colour is not so 
marked. Prussia is somewhat similar to Scotland in its eye colour, the proportions 
being in Prussia 43, 33 and 24 as against 45, 33 and 22 in Scotland for light, 
