100 
S. IKENO : 
the Table of Colours, p. 96). The Ityoflspring were composed as follows :— 
Table II. 
F 2 -generation (1916). 
Yellow 
Orange 
White 
Total. 
Actual 
71 
23 
37 
131 
Expected . 
73-69+5-68 
24-56+4-47 
32-75+495 
on 9:3:4 basis 
65-50+5-72 
32-75+4-95 
32-75+4-95 
on 2 :1:1 „ 
Thus the actual numbers of the three classes of the /4,-oflspring agree with 
the expected ones, either on 9:3:4 or on 2:1:1 basis, though the agree¬ 
ment is much closer in the former than in the latter case. The final decision 
which alternative will be here realised, would however lie possible only after 
the examination of the /4-oftspring ; thus if the segregation under discussion 
will belong to the 2:1:1 type all yellows should be heterozygous, and all 
oranges homozygous, whilst if it will belong to the 9:3:4 type some yellows 
should be homozygous, and some oranges heterozygous. Unfortunately on 
account of the poor germination of seeds the 14-generation contains very few 
individuals, and the results are consequently rather imperfect, because I was 
able to examine the 14-offspring of only 2 oranges, 3 whites and 3 yellows 
in all of which generally very few seeds came to germination, viz. :— 
1 orange has thrown almost exclusively oranges (22 in all), 1 
1 orange has segregated into 9 oranges and 2 whites, 
3 whites have thrown whites only (19 in all), 
1 yellow has thrown only 1 yellow, 
1 yellow has segregated into 5 yellows and 1 white, 
1 yellow has segregated into 6 oranges and 1 white. 
The fact that the ratio of segregation in our case should be 9 : 3 : 4 may be 
concluded from the presence of one heterozygous orange just cited, because in 
the 2:1:1 type no orange should be heterozygous. This orange has undergone 
1 Besides 22 oranges 1 magenta was found among the progeny. As discussed in Chapter 
“ Mutations, etc.”, I (p. 121 ffj this 1 magenta is regarded to have been produced by the reverse 
mutation, and consequently the orange parent is considered to be of the composition whb 
(s. also Table VIH, No. 9 ; discussion, p. 125). 
