G. P. HECTOR 171 
Actually the combination of aB (green leaf-sheath and apiculus with 
coloured internode and stigma) is absent, and the ratio obtained is— 
48 AB : 0aB : 12 Ab : 4 ab 
In such cases we must be dealing either with three factors, two of which 
ate completely linked, or one factor is common to both systems, while a 
second additional factor, interacting with the common factor in sucha 
way that the presence of either is sufficient for the production of colour, is 
responsible for the, colour in the system “leaf-sheath and apiculus ” (thus 
segregating 15: 1). Thus— 
15 A la 
———S 
AB aB : Ab s 6ab ~ 
9 3 3 : 1 
——<—<<—<———— ——— 
12 B 4B 
or ois 12 AB : 0 aB: 3 Ab : 1 ab 
This type of segregation occurs very frequently. 
Lastly, one instance has been found, v7z., in the cross Muramagar x 
Pookhi, in which the parental combinations (in this case coloured ligule and 
coloured outer and inner glumes ; colourless ligule and colourless glumes) 
occur more frequently than expectation if independent segregation is taking 
place, some of the ratios obtained indicating a coupling of the parental gametes 
in the neighbourhood of 7: 1. 
The final conclusions are— 
1. These colour characters are frequently inherited in patterns of groups, 
due either to one and the same simple factor or to the same interacting factors ; 
or due to several factors linked together. 
2. Considered in relation to other systems or patterns, independent 
segregation may take place, but frequently the groups are so inter-related 
that certain combinations, expected if independent segregation were taking 
place, are never found, and these combinations are those which are absent in 
pure-line cultures. 
Grain colour. 
The husked grain of rice is either some shade of red or white. A large 
number of crosses, both natural and artificial; have been examined with 
reference to grain colour and in all, with two exceptions, simple, independent 
3:1 segregation has beenfound. As the inheritance of this character, with 
