MENDELIAN FACTORS IN THE SILKWORM. 
99 
In their works, we find no complex cases of Mendelian inheritance, except 
the varying behaviours, i. e. individual idiosyncrasies of Kellogg, of the 
white-cocooners. These irregularities were, as already mentioned, worked out 
by Toyama. A few other deviations seem to be merely accidental. 
3) Toyama’s results. 
I shall take here only the more complicated of his experimental results 
which I have referred to in the preceding pages. 
A. First example of the “modified dihybrids” 
We denote the factors 0 concerned as : 
C, the colour factor ; c, absence of colour ; 
Y, the yellow factor ; y, absence of yellow ; 
and the gametic compositions ]) as : 
CY, yellow; cY, salmon; 
Cy, greenish white; cy, pure white. 
In the cross CY x cy, F x will be all yellow, which will segregate to four 
forms in F 2 . 
F, 
jl CYCY + 2 CYcY+2 CYCy + 4 CYcy 9 yellow, 
jl cYcY +2 cYcy 3 salmon. 
1 1 CyCy + 2 Cycy 3 greenish white. 
1 Cycy 1 white. 
Analysis of the third generation of this series is given in Table I. 
Fj gametes 
(CY + cY + Cy + cy ) = j 
1) These genetic factors and gametic compositions are merely temporarily assumed 
here. Whether these assumptions are applicable to any other similar cases is to be tested 
by future experiments. 
