208 M. F. GUYER AND E. A. SMITH 
eyes about: one-half normal size, both having coloboma and 
clouded lenses; a male with left eye of normal size, though ro- 
tated forward and containing an opaque lens and an incomplete 
iris, and with right eye abnormally small and containing defec- 
tive iris and lens. } ; 
The fifth generation, then, included fourteen individuals in 
which the eyes were defective: one female and seven males with 
both eyes abnormal, three females and one male with the right 
eye defective, and two females with the left eye affected. 
Some progeny of the sixth generation have been secured (fig. 
5) and the defect is still present. For instance, 28A2, classed 
as normal, although she had a streak across one lens, when mated 
- to 28A3 (right eye defective), brought forth five young on August 
12, 1919, the 38A series, one of which had both eyes defective. 
Other young of the sixth generation will be secured and the 
matings carried farther. This is a slow process for, in our experi- 
ence, not more than three generations can be obtained in two years. 
The rabbits usually breed when six to eight months of age, al- 
though several have been ten to twelve months old before having 
their first litter. 
In all of the matings described in detail so far, the female has 
been from the defective stock. The objection might be raised, 
therefore, that in each new generation we were not getting in- 
stances of true inheritance, but merely a placental transmission 
of antibodies or kindred substances from the blood-stream of the 
mother. While it would be difficult indeed to explain how such 
antibodies could remain undiminished in successive generations, 
nevertheless the situation clearly called for the establishment of 
the descent of the defect through the male line before it could be 
pronounced unequivocally an example of inheritance. Mani- 
festly, if the defect appeared among the descendants of a male 
with abnormal eyes and a female from unrelated and untreated 
stock, then we could be sure that it was conveyed through the 
germ cell of the male alone. 
In order to test this point, the male, 3A1, was bred to a normal 
female, no. 11, obtained from Fort Wayne, Indiana (fig. 6). On 
March 6, 1918, she produced a litter of three, the 12A series, all of 
