Referate. 
Davenport, G. ©. and Davenport, Ch. B. Heredity of Eye-color in Man. 
Science, N. S. 26 1907, p. 589. 
Hurst, C. C. On the Inheritance of Eye Colour in Man. Proc. Roy. Soc , 
B., 80 1908, p. 85. 
These two papers deal with the inheritance of eye colour in man from 
the same standpoint and may be conveniently considered together. In 
each case the authors have arrived at a similar conclusion which may be 
briefly stated as follows. All eyes (other than those of albinos) have a 
layer of pigment on the inner surface of the iris, but in addition to this 
there may be present more or less brown pigment on the outer surface. 
Human eyes may therefore be classified under two headings, viz. (a) those 
with brown pigment on the outer surface of the iris, and (b) those without 
such brown pigment. The former of these two classes containing the various 
shades of browns and greens Hurst calls ‘‘duplex’’, while he proposes the 
term “simplex” for the latter class which consists of blues and greys. As the 
result of a careful investigation among the inhabitants of the village 
of Burbage in Leicestershire Hurst concludes that the duplex type (D) 
behaves as a simple dominant to the recessive simplex (R). The evidence 
upon which he arrives at this conclusion is as follows: 
Result. Expectation 
Mating Nature of mating = 
Duplex | Simplex | Duplex | Simplex 
Simplex >< Simplex N | 101 = All 
Duplex >< Duplex DD >< DD| SEN ee 
or DD ><DR[ a ze 
Duplex >< Duplex DR >< DR 45 | 18 47 16 
Duplex >< Simplex DD > RR (a = All = 
Duplex >< Simplex DR >< RR 121 137 129 129 
The evidence of Mr. & Mrs. Davenport, though much less extensive 
is confirmatory of the view that the presence or absence of brown pigment 
on the outer surface of the human iris constitutes a pair of characters 
exhibiting Mendelian inheritance. 
Hurst subdivides the duplex eyes into three types viz. self-coloured, 
ringed, in which the brown pigment tends to disappear at the periphery of 
the iris, and spotted in which the greater part of the iris may be free of 
brown pigment. He considers that the existing evidence suggests that the 
ringed type is recessive to the self-coloured type, but of the inheritance 
of the spotted pattern there is practically no evidence available. = 
In dealing with these different forms of duplex eyes a complication is 
introduced through growth changes. The brown pigment present in children 
tends to increase with age though to what extent, or till what age, is not 
yet known owing to the limited period of observation. 
