34 
Pigmentation, Susceptibility and Mace Selection 
TABLE XIX. Showing the Number of Cases and the Percentage 
developing subsequent Paralysis, also the Percentage requiring 
Tracheotomy performed, in the various Hair and Eye Colours in 
Diphtheria. 
(i) Hair Colour. 
Black 
Dark 
Medium 
Fair 
Bed 
Number of cases ... 
Percentage with paralysis 
Percentage requiring tracheotomy 
1 
o-o 
o-o 
78 
6-4 
5-1 
303 
3- 9 
4- 9 
134 
4-5 
6-0 
19 
10-5 
10-5 
(ii) 
Eye Colour. 
Dark 
Medium 
Light 
Blue 
Number of cases 
Percentage with paralysis 
Percentage requiring tracheotomy 
86 
4-7 
4-7 
242 
4-1 
3-7 
178 
5-6 
7-9 
29 
3'5 
6-9 
(iii) Hair and Eye Colour Combined. 
Dark hair and 
dark eyes 
Medium hair and 
medium eyes 
Fair hair and 
light eyes 
Number of cases ... 
Percentage with paralysis 
Percentage requiring tracheotomy 
31 
9-7 
32 
169 
3-6 
3-0 
73 
4-1 
4-1 
(6) Pigmentation as a Factor in Race Selection. By comparing the percentages 
in each hair or eye class of the total number of severe cases with recovery with the 
percentage of that class in the general population, an indication is given as to how 
far that class is handicapped by subsequent disability after severe illness, and by 
comparing the percentages in each class of the total number of deaths with the 
percentage of that class in the general population, an indication is given as to how 
far that class is selected for extermination. The effect of selection is so much 
alike in each of the diseases considered that it is unnecessary to consider them 
separately. 
(i) Hair Colour. 
Table XX shows that the medium-haired class is undoubtedly selected both 
for handicap by its greater number of severe cases with subsequent disability, and 
for extermination by its greater number of deaths. 
This is the case in every one of the diseases considered, but to a less extent in 
measles where the fair-haired class suffers more severely. At the expense of the 
