TRANSMISSION OF INDUCED EYE-DEFECTS 209 
which had normal eyes. A litter of seven from the same female, 
sired by 3A1 was born next, and they likewise were normal-eyed 
(series 12B). Still another lot of eight, the 12C series, were 
born of the same parentage, and they, too, were normal-eyed. 
However, on the supposition that the’ defect acted as a recessive 
in the presence of normal eyes, the results were what would be 
expected. 
Next, 12B1, a female, was selected for further tests. She was 
first mated to her brother, 12B3, and the six young born January 
2, 1919, all had normal eyes (fig. 6). If 12B1 were heterozygous 
for the defect, as it was reasonable to suppose, young with 
abnormal eyes should be obtained more readily by mating her 
with 3A1. This was done, but six normal-eyed young, the 31A 
series, were born April 6, 1919 (fig. 6).. Another litter of seven 
normal-eyed young, the 41A series, was born October 6, 1919. 
Thus far no defective-eyed individuals had appeared. 
Next, the females of the 31A series were bred to males having 
both eyes' defective (fig. 6). On October 19, 1919, 31A4, bred 
to 10A4, gave birth to five young, the 48A series. One died two 
days later and of the remaining four, one female has a small left 
eye with cleft iris (coloboma) and opaque lens. No. 31A3, 
mated to 8B, produced a litter of seven on November 3, 1919. 
The five that lived have normal eyes. The other female, 31A1, 
bred to 28A4, bore three normal-eyed young November 5, 1919. 
The male, 3A1, was also bred to normal female 39 from a new 
stock secured in Minneapolis (fig. 7). She gave birth to a litter 
of eight young on July 26, 1918. One of this litter died Septem- 
ber 7. The seven remaining, called series 26A, consisted of six 
females and one male, all with normal eyes (fig. 7). Later, 
26A7, was mated to 3A1 and produced five young, the 32B series, 
on October 5,1919. One died the next day, one of the remaining 
four, a male 32B1, has the left eye smaller than the right, the 
eyeball slightly rotated toward the front, the iris interrupted 
ventrally, and the lens opaque. 
The female, 2643, was bred to 10A4 (both eyes defective) on 
October 22, 1919. All of the eight young brought forth Novem- 
ber 22nd were normal-eyed. On October 22, 26A1 was bred to 
