LOSS OF EFYE-PIGMENT IN GAMMARUS. 327 
were not examined immediately on extrusion, (1) red mated with red 
(male e and female f) gave 11 normal reds and 2 no-white reds ; (2) red 
mated with red (male e with females f and g) gave 12 normal reds and 
5 no-white reds; (3) two black females, 3 red females, and 2 red males 
belonging to this F, generation from the second brood (VII.D.2), left 
together in the same bowl gave 
7 normal blacks, 4 no-white blacks. 
11 Pw reds Dees, = Te AS: 
The proportions are here however not significant, as red may have mated 
with red, as well as red with black. 
Two other experiments give direct evidence of the dominance of 
normal white pigment over its absence in no-white eyes. 
(1) A Red male (VII.E.) with both eyes no-white (RN.), from K 
family was mated with a Black carrying the factor for red (B-+R), and 
there resulted a brood of 14, all normal-eyed, 7 black (B+R-+N) and 
7 red (R+N). When the young ones were mated together, “* no-whites ” 
both red and black appeared in the next generation. 
(2) A Black male (III.J.) carrying the factors for Red and Albino was 
mated with a Black no-white female (pp. 289, 329) and had 92 young 
in four broods, all normal black-eyed. 
That these no-white animals behave as simple recessives is illustrated 
by further matings which will now be described. 
A brood resulting from the mating together of two of the hybrid blacks 
(B+R) of K family (Plate V, Fig. 1) consisted of 9 normal black-eyed 
young, 1 normal red-eyed and 5 black no-whites (VII). Three of these 
survived to maturity, 2 normal black-eyed females and one black no- 
white male. The male A mated with each female (B and C) in turn. 
With female C there were 26 young in three broods, 18 black and 8 red. 
The blacks consisted of 9 normal blacks, and 9 with no-white on both 
sides. The 8 red were 2 normal and 6 no-white on both sides. 
From this it follows that both the male A and the female C were 
hybrids as regards red and black. 
The male when mated with female B gave 42 young in four broods, 
all with black eyes, 25 being normal-eyed and 17 being no-whites. Female 
B is therefore pure black as regards retinal colour. 
Both female C and female B in these matings behave as though they 
were hybrids for the character **‘ no-white.” Their no-white offspring 
when mated together give all no-white young. Thus a male and a female 
Black no-white (in brood B.1.) gave 3 black no-whites, a similar pair 
(in brood B.2.) gave 10 black no-whites. A male and a female, both 
Red no-whites (in brood C.2.) mated together gave 11 red no-whites. 
