D. Macdonald 
21 
light eyes tend to become brown or even dark, and the dark-eyed girls with fair or 
brown hair to become dark-haired. How far these changes are influenced by a 
selective death rate still remains to be determined." 
It would therefore be expected that, if there is any discrepancy from the age 
difference in comparing the results of this inquiiy with those of Tocher's survey of 
school children, a proportion of fair and possibly medium dark takes the place of 
medium and dark at the more advanced age. An appreciable but not large 
number of the children observed in hospital are considerably younger than the 
children on whom Beddoe and Pearson based their results as given above. All the 
evidence, however, tends to show that the colour of the hair and of the eyes to a 
lesser degree darkens with age, in which case a slight excess of fair-haired children 
should be found entering hospital, when compared with Tocher's statistics for school 
children, unless such a result be upset by some correlation between the colour of 
the hair and susceptibility to the diseases considered. This excess is certainly 
present, except in scarlet fever, but it is not great, the percentage of fair-haired 
children varying from 19"3°/ 0 i n scarlet fever to 27'8°/ 0 in measles as compared 
with Tocher's figure for school children for the same area of 21'4°/ 0 - How much 
of this discrepancy is accounted for by the age difference, and how much by some 
correlation between the colour of the hair and susceptibility to the diseases 
considered cannot be definitely stated. As will be shown later, however, there is a 
distinct negative correlation between dark hair and susceptibility, and there is no 
reason why the excess of fair-haired children entering hospital should not be due 
as much to some such correlation between fair hair and susceptibility as to any 
error from age difference. 
(3) The Incidence of the Diseases considered in the different pigmentation 
Types. It was thought that, by comparing the percentages of the various hair and 
eye colours of children suffering from scarlet fever, diphtheria, measles and whooping 
cough with the percentages of the various hair and eye colours given by Tocher for 
the areas corresponding to the areas from which these children were drawn, some 
definite result might be obtained, indicating the pigmentation type most liable to 
suffer from any of these diseases. 
As will be seen from Table II there is, with regard to the colour of both hair 
and eyes, a striking similarity between the percentages of each colour attacked by 
each of the fevers considered, and these percentages differ considerably from 
Tocher's percentages of the general population for the same area. 
With regard to the pigmentation of the hair, in every case the medium is 
considerably in excess, the dark deficient and the fair and red about equal when 
compared to their proportional representation iu the general population. The 
colour of the eyes shows a similar result, the medium considerably in excess, the 
dark and blue deficient, the light being the only variable colour, being in excess in 
diphtheria and whooping cough and deficient in scarlet fever and measles as com- 
pared with the general population. 
