142 Pigmentation Survey of School Children in Scotland 
tion of the population throughout the country ? In other words, if divergencies 
from this even distribution occur, what is the relative degree of divergency for 
each locality ? This is, in short, the third problem which is discussed in sec- 
tion (7). 
{d) The degree of local segregation of each of the colour classes constitutes 
the fourth problem. If the population is not evenly distributed with respect to 
the colour classes, which class shows the greatest degree of isolation into separate 
groups ? This can be determined by considering successively the nature of the 
distribution of relative local differences of each class collectively and without 
reference as to where each local difference occurs. That is to say the relative 
local differences of each class are successively considered interlocally as a whole 
and the variability of each distribution determined. The greater the variability 
of the distribution of relative local differences for a class the more uneven will be 
the distribution of the class throughout the country, and the greater will be its 
massing into groups, and thus the greater will be the local segregation of the 
class. This problem is considered in section (8). 
(e) It is important from the eugenic standpoint to know whether pigmenta- 
tion is associated in any way with disease, inherited or non-inherited defects, race, 
or with density, fertility or other characters of the population. These problems 
are considered in section (9). 
{f) An interesting problem which is concerned with sexual differences is 
considered under section (10). The problem may be divided up into three parts. 
1. In what respects, if in any, do the constants found for boys and girls differ? 
2. Are there any significant pigmentation differences between boys and girls ? 
3. What is the average resemblance between the male and female factors of the 
population ? 
{g) The next problem is one concerning urban and suburban populations. 
The questions may be put. 1. Are there any significant differences between the 
purely urban and the suburban and rural populations, and if so in what respects 
do they differ ? 2. What differences occur (a) within each urban population {i.e. 
intralocally), and (^8) between different urban populations {i.e. interlocally), and 
are these differences environmental, racial or both ? This problem is dealt with 
in section (11) with special reference to Glasgow and its environs. 
(/«-) A further problem which is of importance turns on the point as to 
whether hair and eye colours are independent variables or whether they are 
dependent. It is desirable therefore to know what degree of association, if any, 
exists between hair and eye colours. If association is found to exist does the 
relationship found agree or differ with that indicated by former surveys of adults 
and children. This problem is considered among others in section (12). 
{i) The pigmentation data present other problems for solution, such as 
whether brothers and sisters or cousins resemble one another to any degree in 
hair and eye colour. These problems are not dealt with in this memoir. 
