170 CORRELATION OF COLOUR CHARACTERS IN RICE 
to develop in some part of the pattern, so they could not be due to accidental 
crossing, and moreover, the F, plants, though not bagged, were grown isolated 
in pots. Accidental mixture too is ruled out, as we have no such types. It 
would seem, therefore, that they are real breaks in the pattern systems, or, at 
any rate, extreme negative variations in the development of colour in the 
part concerned. If, however, they are breaks in the pattern systems and the 
patterns are due to one unit factor, it is difficult to understand by what mecha- 
nism these constituent parts of the pattern can break away, as they appear 
occasionally to do. Another case of a break in correlation is discussed below 
under grain colour, viz., between red colour in the grain and colour in the 
ligule of the leaf. Similar cases of breaks in colour correlation have been 
described by Parnell! in rice ; and in other plants, notably by Emerson? in 
maize. 
Again, it has been proved that in same varieties localizations such as 
leaf-sheath, apiculus and stigma stick together absolutely and belong to the 
same system, as in the crosses Pankhiraj x Pookhi and Matichak x Pookhi, 
where this pattern segregates 3: 1 in F, (Nos. 1 and 2 discussed above) ; 
but again in variety Noachur x Pookhi (No. 3 above) and others, the 
leaf-sheath and apiculus belong to a different system from the stigma, a 
system due to two interacting factors, segregating 15 : 1; whereas the 
stigma is united with the internode, and is due to a single factor and 
segregates 3: 1. 
2. These patterns or systems have been shown sometimes to segregate 
independently of other systems, giving all expected combinations in expected 
ratios in F,, but frequently certain expected combinations are wanting, and 
the wanting combinations have been shown to be those which never occur in 
pure-line cultures. Examples of this are cases such as the cross Noachur x 
Pookhi. 
In Noachur the system “ leaf-sheath and apiculus ’’ (A) segregates 15 ; 
1; the system “internode and stigma ”’ (B) segregates 3: 1. 
On crossing with a colourless type (ab) you expect, if independent segre- 
gation is taking place, 
15 A che Lee 
3B Smeg elp 
45 AB : 3aB : 15 Ab : I ab 
‘Parnell, F. R., Ayyangar, G. N. R. and Ramiah, K. ‘‘ The Inheritance of Characters in 
Rice, I. ’’ Mem. Dept. Agri. India, Bot. Ser., Nov. 1917, vol. 1X, no. 2. 
2 Emerson, R. <A. ‘ Genetic Correlation and Spurious Allelomorphism in Maize. ”’ 
L'wenty-fourth Ann. Rep., Agri. Exper. Station, Nebraska, 1911, pp. 59—82. 
