198 Idle 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 piguient on the outer 

 surface of the iris to prevent the dark purple pig- 

 ment — the uvea — on the inner surface from being 

 seen through the meml^rane, 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, l:)lend 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. 

 Griven 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. I^Tature, 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 al^out 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, imd in 



