290 
COLOUR IN NATURE 
CHAP. 
haired belong to the Teutonic races ; in other words, 
the difference in hair-colour corresponds to all those 
profound mental and moral differences which separate 
Celt from Saxon. That the mental and moral dif¬ 
ferences are associated with physical ones hardly 
needs proof to the biologist, but there are fortunately 
some exact observations. During the course of an 
extended series of observations on the specific gravity 
of the blood, Dr. E. Lloyd Jones found that this was 
markedly greater in dark-eyed persons than in light¬ 
eyed ones, and he is of opinion that the difference is 
fundamentally a racial one. Further, there is reason 
to believe that the dark-haired people are better able 
to stand prolonged dosing with drugs like mercury 
than the fair-haired ones ; and, according to Beddoe, 
the dark-haired persons in Britain are more prone to 
phthisis than the fair. It thus seems that just as the 
phthisical tendency and the other characters tend to 
eliminate the dark people from cold climates, so ap¬ 
parently the fair people are less fitted to survive, or 
at least less likely to become dominant, in hot 
countries. Facts of this kind have probably an 
important bearing upon the coloration of mammals 
in general. The constancy of the coloration, and 
the closeness of its connection with the constitution, 
are at least of much interest in relation to the 
general question. 
The Origin of Melanin 
As to the direct relation of the amount of pig¬ 
ment to the general metabolism, many would say 
that the pigment is directly derived from the 
