MENDELIAN FACTOES IN THE SILKWOMS. 
103 
(I) 
(II) 
Dominant (European) white W 
IY or Iy 
Recessive (Asiatic) white 
w 
iy 
Yellow 
Y 
iY 
In terms of Toyama’s factors 
the possible schemes 
of inheritance in 
crosses between dominant and recessive whites are as follows : 
P 
F, 
f 2 
1) WW x ww 
all white (Ww) = 
all white 
2) Ww x ww = 
” ” (Ww + ww) = 
r 3 yellow 
3) WY x ww - • 
f yellow (wY) = 
l 1 white - 
1 
l white (Ww) = 
all white 
On the other hand, in terms of my factors the possible pedigrees of the 
cyosses under review will be as follows : 
P 
Fj 
f 2 
1) 
iyiy x 
iyiy = 
all white (Iyiy) 
= 
all white 
2) 
iyiy x 
iyiy = 
all white (Iyiy + iyiy) = 
all white 
rl3 white 
3) 
IYIY x 
iyiy = 
all white (IYiy) 
l 3 yellow 
, 13 white 
, 1 white (IYiy) 
( 3 yellow 
4) 
IYiY x 
iyiy = 
J 
) 
, 1 white 
1 yellow (iYiy) 
( 3 yellow 
r 13 white 
5) 
IYIy x 
iyiy = 
( 1 white (IYiy) 
t 3 yellow 
U white .(Iyiy) 
= 
all white 
Thus it is clear that by thorough experimental study of the hereditary 
behaviours of crosses between dominant and recessive whites we may deter- 
mine which of the two views here touched upon is more adequate. It is 
hoped later to take up a detailed study on this subject. 
4) Coutagne’s results. 
In Coutagne’s experiments several examples of complicated Mendelian 
