326 E. J. ALLEN AND E. W. SEXTON. 
SECTION II]. THE NO-WHITE EYE 
(Plate V). 
As was mentioned in the former paper (p. 21), a mutation occurred in 
which the superficial chalk-white, extra-retinal pigment that forms a 
reticulation in which the ommatidia lie was entirely absent. This was 
called the “ no-white ” eye, and a black one was figured (Plate I, Fig. 6). 
A red one is figured in Plate VII, Fig. 5, of this paper. 
The chalk-white extra-retinal pigment is much less resistant to alcohol 
and formalin than the black or red retinal pigment, quickly disappearing 
when placed in either of these liquids. It may be noted here, also, that 
the red retinal pigment is more easily dissolved by alcohol than the 
black, the latter being practically insoluble. 
Animals occur in which the white pigment is present in the eye on one 
side and absent in that of the other. For details of experiments with these 
see p. 340. 
ORIGIN OF EXPERIMENTAL STOCK. 
The “* no-whites ” with which most of the experiments have been made 
had the following history : 
A pure black male from Chelson Meadows, which had been tested by 
mating with two wild females and with two other red females, and had 
given normal results, was mated with a pure red female (a descendant 
of the fourth brood of Female A of the former paper, p. 22) and had a 
large family (Family K, in former paper, p. 31). Of this family 24 sur- 
vived, 5 males and 19 females, all normal-eyed hybrid blacks ; the young 
from their matings are now called “VII.” At least 6 of these females 
6 
when mated with males from the sane family gave some “ no-white ” 
young, both black and red. Details are given in the former paper, p. 44. 
PROOF THAT “ NO-WHITE,” 1.e. THE ABSENCE OF WHITE PIGMENT, BEHAVES 
AS A MENDELIAN RECESSIVE TO THE PRESENCE OF WHITE PIGMENT. 
One of the red ** no-whites ” from K family (VII, D.) was mated with 
a black male from the ordinary hybrid stock (Plate V, Fig. 2). There 
were 29 young, 12 black and 17 red, all normal-eyed, showing that the 
presence of white pigment is dominant, and its absence in the * no-white ” 
eye IS recessive. 
An F, brood got by mating together two of the red young ones from 
the first brood (male e and female g) gave 3 * no-whites ” to 13 normal, 
showing that the abnormality behaved in a Mendelian way and both the 
red-eyed animals carried the factor for no-white. In other broods, which 
