INHERITANCE OF EYE-COLOUR IN GAMMARUS. 39 
The total number of young hatched was 5494. Of this number 388 
were the black-eyed offspring of P. j x R.@ and 1175 of P.? x R. 3. 
The number of young from the other cross, H. x R., was 3931—1992 
Black-eyed and 1939 Red-eyed—1134 Black and 1098 Red in the mating 
H. 3 x R. 9, and 858 Black and 841 Red in the mating H.? x R. 3. As 
will be seen, the proportion is not quite exact, the Blacks being rather in 
excess. It appears to vary a good deal with the individual, though 
perhaps the number of offspring from a single pair is not sufficiently large 
to eliminate mere chance variation. Some animals have a succession of 
broods fairly evenly divided into Black and Red, while others have a 
preponderance of one colour or the other, others, again, having first one 
brood unevenly divided, the next restoring the balance, and so on. Ex- 
amples of the first will be found in Exps. 87 and 57. 
In Exp. 87 (9 H., with the same mate for all the broods)— 
Brood 1 numbered 27 — 14 Black and 13 Red. 
nO ig Tee gua 
Se ae ieee pity 
Some a ae = ey bah. 
oe MO [Qe 55 ‘ mou 
CROC Tey: [eis be 4s 
mea. = 20 = 10 ee Nise § 
fae Sayan ts ont aera sist | 
ac Gara 30r = 914 ga Digit 
EOLA», 4 — 12 ae 19 
191 — 95 Se o6kt, 
Exp. 57 (2 H., with 3 different mates)— 
Brood 1 numbered 8 — 3 Black and 5 Red. 
ae ss 22 = 11 a 1 ae 
eet . a0) — 16 Hs Lae 
MarR enta fats 33 = 20 Pais Seis 
reese) x Piles Wl: 4 LOR. 
| ates Get phe wie. Cee? Oh 
Pe he aaieal| 20°= 8 m foro 
| Je 8 ss aoe 20 Ke nS 
Gober. “G <- th eee 1G ie 
998 —115 otis. 
For examples of the preponderance of one colour Exps. 60, 61, 71, and 
95 will serve; 60 isa ¢ H. and 71a? H., both had 4 broodsfeach,§with 
117 and 118 young respectively. 
