GENETIC STUDIES ON THE SILKWORM 
The observed results were : 
Cases included in Other cases Totals Expected 
Table I 
Class VII 7 3 io 9.4 
Class VIII o o o 0.6 
Though the number is not large enough, the expectation was fairly realised 
in all of the three forms A, B and C. 
B. Q.-Y Coupling. 
W hen Q, and Y are brought into a hybrid by the same parent, coupling 
occurs between these dominants. In contradistinction to the case of repul- 
sion, all possible F 2 forms are produced in the ordinary as well as in the 
sexually dimorphic coupling, so that the actual proportion of gametes is 
almost impossible to make out so long as the breeding is confined inter se. 1 ^ 
F 2 offspring ex normal yellow x plain white. 
(PftYPqy x paYPqy) 
Norm. yel. 
Norm, w 
h. PL yel. 
PI. wh. 
Totals 
C 2i'i4 
'35 
13 
'3 
25 
186 
C 22' 1 4 
265 
40 
20 
78 
403 
C 23^4 
223 
40 
27 
69 
359 
C 24*14 
64 
9 
3 
'7 
93 
C 25-i'i 4 
74 
10 
9 
24 
117 
C 25-2'i4 
75 
10 
1 
^5 
1 1 1 
C 25-3'i4 
146 
J 9 
1 1 
48 
224 
C 26-1 '14 
119 
16 
16 
23 
!74 
C 26-2' 1 4 
113 
9 
8 
3i 
161 
C 26-3'i4 
218 
20 
23 
47 
308 
C 27-1' 14. 
'38 
19 
1 1 
44 
2 1 0 
C 27~2'i4 
99 
14 
9 
42 
164 
C 27-3' 1 4 
1 1 1 
'7 
13* 
3i 
172 
C 28-2' 1 4 
4i 
7 
3 
•3 
64 
1) I formerly regarded the coupling between S or M and Y as a case of the ordinary nature 
occurring in the frequency 7 : I : I : 7 in both sexes (1913 b). 
