GAMETIC COUPLING AND REPULSION IN THE SILKWOSM. 
121 
the striped and normal yellows nearly in the proportion of 1 : 1, the actual 
result being 269 striped yellow: 203 normal yellow. This result, together 
with others to be described later, indicates that the striped parent was homo- 
zygous for yellowness, but heterozygous for striped character. As the 
normal parent is of course homozygous both for the marking and . colour, 
the case may be graphically represented as follows : 
P (1910) Normal white x Striped yellow 
ssNNyy SsnnYY 
l 1 i 
F t (1911) Striped yellow Normal yellow 
SnYsNy snYsNy 
Fj normal yellow' mated inter se gave the following offspring. !) 
Lot No. Normal yellow Normal white Plain yellow Total 
H. 2.’ 11 80 30 28 138 
Expectation 69.0 34.5 34.5 138.0 
Here again normal and yellow characters are brought into the cross by 
the different parents, and therefore a perfect repulsion occurs between them. 
c) A Japanese normal white (Aojilcu) female was crossed with a homo- 
zygous plain yellow of Chinese origin. The F, larvae which were all normal 
yellow r yielded three forms of F 2 offspring. 
Lot No. Normal yellow Normal white Plain yellow Total 
H. 5.’ 11 123 88 61 272 
I had only one mating of this cross reared in 1912, nevertheless it was 
the most important mating for the confirmation of the assumption that a 
perfect repulsion takes place between the normal and yellow characters, 
when these are brought into one individual by the different parents. Here 
the cross had been made between two homozygous strains, the zygotic 
constitutions of which were exactly known, and the hereditary behaviour 
1) As to the behaviour 
if the Fi striped yellow, see the later pages. 
