198 Ldle Days in Patagonia. 
thing unheard of in nature. Then we have the green, 
beginning with the palest sage green, and up through 
grass green and emerald green, to the deepest sea 
green and the green of the holly leaf. Do such eyes 
exist in nature? In theory they do. The blue eye 
is blue, and the grey grey, because in such eyes 
there is no yellow or brown pigment on the outer 
surface of the iris to prevent the dark purple pig- 
ment—the wvea—on the inner surface from being 
seen through the membrane, which has different 
degrees of opacity, making the eye appear grey, 
light or dark blue, or purple, as the case may be. 
When yellow pigment is deposited in small quantity 
on the outer membrane, then it should, according 
to the theory, blend with the inner blue and make 
green. Unfortunately for the anthropologists, it 
doesn’t. It only gives in some cases the greenish 
variable tinge I have mentioned, but nothing ap- 
proaching to the decided greens of Broca’s tables. 
Given an eye with the right degree of translucency 
in the membrane and a very thin deposit of yellow 
pigment spread equally over the surface; the result 
would be a perfectly green iris. Nature, however, 
does not proceed quite in this way. The yellow 
pigment varies greatly in hue; it is muddy yellow, 
brown, or earthy colour, and it never spreads itself 
uniformly over the surface, but occurs in patches 
grouped about the pupil and spreads in dull rays or 
lines and spots, so that the eye which science says 
“ought to be called green” is usually a very dull 
blue-grey, or brownish-blue, or clay colour, and in 
