D. Macdonald 
37 
(iii) Hair and Eye Colour combined. The determination of the effect of 
selection on the race with regard to hair and eye colour combined is not at pre- 
sent possible as no statistics are available of the different combinations of hair 
and eye colour in the school children of Glasgow*. 
(7) Pigmentation and Geographical Distribution of Disease. In connection 
with pigmentation and the severity of these diseases, the following facts given by 
Clemowj- are of interest. "Scarlet fever," he states, "is essentially a disease of 
temperate climates. In the tropics it is almost unknown. The influence of race 
is uncertain. People so ethnological ly distinct as the Chinese, the natives of 
South Africa and the inhabitants of the principal European countries all suffer con- 
siderably from the disease. But it is certain that some races are more susceptible 
than others. The statistics of recent censuses in the United States of America 
tend to show that the disease is less prevalent and less fatal among the negroes 
and Red Indians than among the whites. In the few cases of scarlet fever observed 
in India, almost all have occurred among Europeans, and a very small number in 
natives of the country. In Egypt the disease is rare, but the infection is not 
infrequently imported, and when it does attack Egyptian children is of a mild 
character. 
Diphtheria bears a close resemblance to scarlet fever in its distribution. The 
influence of race has never been fully determined. All the great divisions in the 
human family, including pure Mongols and full-blooded negroes, seem to be 
susceptible to the disease, though probably both their susceptibility to attack 
and their power of recovery vary greatly. In China, for example, the disease is 
said to be much more intense and fatal in natives than in European residents, 
while in the United States the white races suffer much more than the black. 
Measles is one of the most widely prevalent of all diseases. In its relation to 
race, it appears to be as indifferent as in its relation to most other external con- 
ditions. All races are susceptible, and it seems to be as capable of attacking the 
Chinaman, the Hindu and the Negro as the European. It appears, on the whole, 
to be decidedly less common in the African Negro than in most other races. 
Whooping cough has an extremely wide distribution. Racial susceptibility 
appears to be a factor of little importance, for all races are affected, though some 
more severely than others. In the United States the Negro inhabitants fall victims 
to it much more readily than those of other races." 
It would appear from Clemow's facts that scarlet fever and diphtheria are less 
prevalent and less fatal among the darkly pigmented races, but on the other hand 
measles and whooping cough seem to be equally severe, irrespective of colour. 
It seems that the statistics on pigmentation on which the results of this in- 
quiry are based as regards susceptibility and recuperative power, although probably 
* [They exist in Tocher's original schedules and no doubt could be easily extracted. Ed.] 
t Clemow: The Geography of Disease. 
