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infected than a child belonging to any other category. The dark type is the least 
liable to infection. It is unnecessary to quote his conclusions in detail ; he has 
made out a number of similar points. The Birmingham and Glasgow data thus 
seem to come into conflict ; but a possible explanation may be found in the fact 
above noted of the different composition of the two populations. The different 
racial groups in Glasgow may possibly represent types whose liability to disease is 
of unequal intensity, while no such racial differences exist in Birmingham. At 
this point we are approaching the question of local races in man, a subject about 
which, as yet, very little is known. It is quite uncertain whether we can justly 
use the term local races, and we are entirely in the dark as to how far those 
characteristics which are supposed to determine local races are to be attributed to 
the influence of heredity or of the environment. 
Certain of Macdonald's results refer to the mortality in the hospitals and the 
power of the children to recuperate. These results, which are based on data 
collected in the hospitals alone, cannot be affected by the objection on the ground 
of personal equation which might be brought against his comparison of the hospital 
data with those collected for the school children outside. This latter series of 
results confirms his general conclusion that pigmentation is a factor in selection, 
since he finds that ability to resist disease when once contracted is connected 
with hair and eye colour. 
To sum up: The conclusions reached in the first section of this paper would 
seem to indicate that pigmentation is not a factor in selection ; but the data 
at our disposal do not enable any very decisive answer to be given. The apparent 
opposition between these results and those reached by Macdonald may possibly be 
explained by the fact that the data used in the two inquiries are derived from very 
differently composed populations. 
II. The Relation of Pigmentation to Height and Weight. 
Introduction. In the introduction to the first section of this paper attention 
was called to the small quantity and vague character of the work which had been 
done upon the problem with which that section was concerned. But in connection 
with this second problem we find an almost complete absence of exact investigation. 
The interest of the question in relation to local races and similar biological 
subjects is obvious ; nor is its importance from other points of view less great. 
Until we have some exact knowledge of the relative value of hereditary and 
environmental influences, we are not justified in attributing greater importance to 
the one than to the other. In spite of this absence of knowledge it is the fashion 
at the present day to attribute all low averages of such characters as height and 
weight, when found in connection with poor social conditions, to those conditions 
no pause is made to enquire whether the low average of the physical measurements 
might not be racial characters which are developed without, or at least with only 
slight, reference to the environment. Now, it is a matter of common knowledge 
that races are distinguished by differences in pigmentation ; if, therefore, a relation 
Biometrika vm 47 
