LOSS OF EYE-PIGMENT IN GAMMARUS. 289 
The constitution of the albino imperfect-eyed female is ‘ as already 
seen on p. 276, that of the hybrid black male with which it was mated is 
: The gametes are therefore for the male C B and C R, for the female 
eBandcR. The F, zygotes resulting from the mating of these two will 
be one Cec B B, a black carrying albino, two Ce BR, blacks carrying 
red and albino, and one Cc R R, a red carrying albino. 
If we now cross an F, black from the first of the above matings 
with an F, hybrid black from the second, we have :— 
VLA. ?x g¢ILA. 
CcB x CceBR 
Female gametes:— CB, C, cB: c 
Male Q CB. CR, c B, eR 
ges noes oB |.¢ pepe cleeatae 
CrB CB GEy) £B | 
alread ee hee | 
CR CR CR CR = 
CB C c B c 
ec B c B ec B ec B 
CB c | .¢.B c 
eR eR 
cR eR | 
That is 9 black, 3 red and 4 albino. 
Hypornesis II. On the second hypothesis the all-white perfect-eyed 
male is constitutionally a pure red, but the non-appearance of the red 
is a pathological condition which is not inheritable. Its constitution 
aN 
J 
may then be represented as , and if it is mated with the albino female 
CR 
carrying black and red we shall have :— 
CR 1¢.B 
OMieic Ey 
The gametes for the male will therefore be C R only, for the femate 
eBandc R. 
The F, zygotes resulting from the mating of these two will be Ce B R 
and Ce RR, giving black and red-eyed animals in equal numbers. 
If one of these F, black-eyed animals (VI) is mated with a black from 
brood If, carrying red, we shall have :— 
VILA. Oo xc Gi A 
CcecBRx CcBR 
NEW SERIES.—VOL. XI, NO, 3. DECEMBER, 1917. U 
