308 E. J. ALLEN AND E. W. SEXTON. 
reds in this generation are mated, there would be albinos in the offspring. 
Further, in each case, in addition to the usual imperfect-eyed albinos 
cR cB cB all-whites of the same hypothetical constitution as the 
ek, cB; CR, SiN 
original “ all-white’ male from red stock - should occur, and if these 
resemble the original parent they will have perfectly formed eyes. 
According to Hypothesis II the Reds can also be mated in three 
different ways. The results would be :— 
(1) CCR RX OCR R 
Gametes all C R 
Zygotes all CC RR. 
That is, all red. 
(2) Circ ko ree io kek. 
Male Gametes CR) cl 
Female — ,, Can caw 
Zy gotes CC RR Cicmkik.. © chi Ry -c.cthwk 
That is, 3 reds and | albino. 
(3) CCR ARS Ce RR 
Male Gametes CR 
Female _,, CR and cR 
Ly gotes CGR AR andy Cc RoR 
That is, all red. 
In two of the instances therefore the offspring would be all red-eyed. 
in one instance there would be albinos in the brood. 
Experiment has shown that when reds of the F, generation are mated 
together some broods consist entirely of red-eyed young, whilst others 
consist of reds and albinos. Further, the albinos when they occurred 
were of the usual imperfect-eyed type. Hypothesis II is therefore in 
agreement with the experimental facts, whilst Hypothesis I is not. 
The following list shows the Red-eyed young and the matings made 
to prove their constitution. 
VI.A.1.m. Male, Pure Red (Plate I). 
Matings :—(1) with female p of its own brood, (R-+-A) ; 
72 young, all Red (Plate IV, Fig. 11) ; 
(2) with female q of its own brood, (R-+-A) ; 
32 young, all Red (Plate IV, Fig. 10) ; 
(3) with female [IV.O (B+ A); 39 young, all 
Black ; 
(4), (5) mated with 2 Albino females: ate 
them. 
