LOSS OF EYE-PIGMENT IN GAMMARUS. 339 
mated together have given 106 young, 85 Albino-eyed and 21 Albino 
no-whites. 
(c) The first F, brood from F, albinos (A+R+NxA+R-+N) from 
the family described on p. 336 numbered 55, 45 usual-eyed albinos and 
10 albino no-whites, i.e. Colourless. Theory requires 41 albinos and 14 
Colourless. 
2. A female with both eyes Colourless (AN-+R) (Plate VII, Fig. 6) 
(whose parents are shown on Plate I, viz. I.E.3.1. 6 and hE3.0. 9 
and whose ancestry is discussed on p- 336), the colourless character 
having originated independently, was mated with a Red No-white 
male RN descended from F amily VII. The resulting broods are charted 
on Plate V, Fig. 4, there being 177 young, all with Red No-white eyes. 
The offspring obtained by mating together individuals from the first 
brood of these young ones are shown on the plate. In the ten broods 
figured there were 124 young, 89 Red No-whites (=RN +AN) and 35 
Colourless (AN+R). Altogether in this generation we have obtained 
481 young, 359 Red No-whites and 122 Colourless. Theory requires 
361, e ar. 120 
735) 
From the mating of the first two F » young which matured, a Red No- 
white male with a Colourless female, 24 young were obtained, RN+- 
AN 14 and AN-+-R 10. The first mating from the next generation le 
(RN-+- AN x RN+ AN) produced 14 RN-+-AN and 3 AN-+R. 
3. Of the three Colourless-eyed young referred to on p. 338, which 
arose independently, two survived, a male and a female. These two 
mated together and the three first broods are shown on Plate V ) Biged: 
Altogether they produced 85 young, all Colourless (F,). The first brood 
of these has reached maturity, and mated together these have produced 
386 young all with colourless eyes (#',). The first two of these broods 
are shown on the Plate. Some of these F » broods have just reached 
maturity, and in chance matings within the brood have produced 10 
young, all Colourless (F;). 
SECTION V. ONE-SIDED NO-WHITES. ANIMALS WITH ONE 
KYE NORMAL AND THE OTHER ABNORMAL. 
A number of instances have occurred in which the eye on one side 
of the head was normal, whilst that on the other was either a coloured 
“no-white ” eye or a colourless eye, 1.e. an albino “ no-white.” 
In most cases these animals died before maturity, so that up to the 
present, we have never had males and females mature at the same time, 
to breed together. 
