'34 
GENETIC STUDIES ON THE SILKWORM 
If the heterozygosis is brought about by crossing the homozygous normal 
with the pale-quail, F 2 results are practically the same with those given 
above : 
F 2 
ex normal x 
pale-quail. 
Normal 
Plain 
Quail 
Pale-quail 
Totals 
A 413^5 
2 1 2 
52* 
64 
25 : 
353 
A 45 2'i5 
152 
49* 
59 
i5" : 
275 
A 453'i5 
183 
59 * 
44 
20 * 
306 
A 354'i 5 
168 
. 60 
68 
18 •'= 
314 
A 456'i 5 
168 
48 
46 
17 
279 
Totals 
883 
268 
281 
95 
1 527 
Expected 
859 
286 
286 
96 
1527 
Ratio 
9 
: 3 
: 3 i 
1 
results of back-crossing follow : 
Fj normal 
22 (ex 1 
lormal x pale- 
-quail) mated to double 
recessive 
Normal 
Plain 
Quail 
Pale-quail 
Totals 
A 375''5 
126 
116 
ny 
95 
454 
A 459' 1 5 
95 
82 * 
73 
75 * 
325 
A 460' 1 5 
85 
86 
99 
85 * 
355 
Totals 
306 
284 
289 
255 
ii 34 
Expected 
283.5 
283.5 
283.5 
283.5 
1 1 34.0 
Fj normal 
SS ( ex 
normal x pale 
-quail) mated to double 
recessive 
Normal 
Plain 
Quail 
Pale-quail 
Totals 
A 461'J 5 
90 
62 * 
81 
7i 
304 
A 462'] 5 
58 
49 * 
60 
58* 
225 
A 463' 1 5 
72 
74 
61 
70* 
277 
A 464' 1 5 
49 
65* 
74 
46 : 
234 
Totals 
269 
250 
276 
245 
1040 
Expected 
260 
260 
260 
260 
1040 
The results mentioned above can 
be put into 
a diagram as follows 
