G. P. HECTOR 161 
pure-line material has been used throughout. These crosses will be described 
in order. 
1. . Variety Pankhiraj x Variety Pookhi. The system “ coloured leat- 
sheath, apiculus, stigma ” has been found to stick together absolutely, giving 
3 coloured plants: 1 green plant in F,, the total of 5 families giving 3-2 
coloured : 1 green (cf. tables above and Appendix II). 
2. Variety Matichak x Var. Pookhi. The same combination behaves 
the same way as in No. 1, the total of nine families giving 3:2 coloured: 1 
green. 
3. Variety Noachur x Var. Pookhi. 
(A) The system “‘leat-sheath and apiculus” sticks together (2 
exceptions were found out of 1,199 plants, vz., two plants with 
coloured apiculus but green leaf-sheath) and segregates 15 
coloured : 1 green in F, (total of 3 families gave 16°1 coloured : 
1 green). 
(B) The system “‘ internode and stigma ”’ sticks together (3 exceptions 
were found out of 1,199 plants, wz., three plants with coloured 
stigma and green internode) segregating 3 coloured: 1 green 
(total three families gave 2°6: 1). 
(C) The colour in the outer and inner glumes gives 3 coloured : 1 green 
(total of three families gave 3:1: 1). 
In this variety there are thus three systems: (1) “‘leaf-sheath and 
apiculus ” (2) “internode and stigma ” (3) “‘ outer and inner glumes.” We 
shall call these A, B, C and treat each in relation to the other two. 
I. Aand B. A alone segregates 15: 1, B alone segregates 3:1. On 
crossing with a colourless type (ab), we should therefore get, if A and B are 
due to different factors segregating independently of each other- 
OAC elie, 
3B ele 
45 AB : 3 aB : 15 Ab : 1 ab. 
Actually observed, 870 AB : O aB : 261 Ab : 68 ab (3 families of 1,199 plants). 
The class aB (¢.e., the combination of “ green leaf-sheath and apiculus ” 
with “coloured internode and stigma ’’) is absent. 
This result can be brought about if system B (internode and stigma) 
is due to a single factor, and system A (leaf-sheath and apiculus) is due to 
two factors, viz., to the factor responsible for B, together with a further 
factor, interacting with the factor responsible for B in such a way that both 
or either produces colour. This is the same as saying that one factor is 
