INHERITANCE OF EYE-COLOUR IN GAMMARUS. 43 
Broods in which 50% and over survived to maturity. 
| Black. | Red, 
Black 5 | | : i a < 
and Red | 2 oie a g 5 = a g BS. = 
Crosses. 5 Se = Ge = a = os 3 5S 
r= a> 3s = 5 is = Pr) > 
5 2H = ) cI 5 = o SI a 
Gee Ae 5, | Aa hi cs cs E Fa 5 B 
P.xR. 10 106 83 | 50 33 
R. x P. 25 299 |. 240- | 129 111 
H.x R. 43 ; 551 387 955 S100 282 196 90 101 269 191 
RixH. | 37 510 Sewriiison) “losa Mieeo 1 ism. WT 92 241 164 
Broods in which less than 50 % survived. 
P.XR.. | -10 142 Silky, eeliGnn. 1S 
R.x P. 26 492 Gill foarte Ag 
Blaek | 
Crosses 
12 Seg 7 194 79 | 40 39 
PoSeee 5 57 28 10 18 
Eesce 9 169 40 17 23 
HesxeH! 13 286 30 i 15 220 eg, 6 Z 66 8 
RECORDS OF ABNORMAL EYES: ‘“NO-WHITE,” 
* PART-WHITE,” AND “ ALL-WHITE.” 
Attempts at breeding the animals together to ascertain if the “ no- 
white,” “‘ part-white,” and “ all-white ” variations follow the Mendelian 
lines of inheritance have so far not succeeded, although these abnormalities 
seem to run in certain families and not in others. For example, in the F, 
Hybrids (p. 31) a great number of cases occurred in Families A and K, 
only one case in M, and none in the other families. 
_ Some instances may be given in illustration of the proportions and 
degree per brood of the “ no-white”’ variation. In K family at least six 
normal-eyed females transmitted this strain, some more than others, and 
the proportion of “* no-white ”’-eyed in their broods was much higher than 
in A family. These females mated in the brood-bowl and were removed 
to extrude their young, and then returned to the bowl to mate again. 
During the month of June, 1915, 20 broods were extruded by the different 
K females (some of them having two broods each in the month), and 
