H. Martin Leake and B. Ram Pershad 9 



These figures indicate sufficiently that the development of the 

 purple colour is due to a single factor, which we have termed M ; and 

 this conclusion is confirmed by the series of crosses which have been 

 made between MP or PL and white ( W) and their reciprocals. 



The R factor. 



The nature of this factor as an intensifier, changing the P into 

 the RP form, is made clear in the following table : 



Number of families 

 PPRr 19 



Expectation 1 : 3 



PpRR 117 



Expectation 1:2:1 



PpRp 32 



Expectation 4:2:1:6:3 



The approximation between the actual figures and those demanded by 

 our assumption is sufficiently close when due allowance is made, for 

 the reasons already given, for the deficiency in the number of whites. 



The conclusion is confirmed by the results obtained from the crosses 

 which have been made. 



W LP P PW RP 



In both cases the expectation is based on the assumption that the white 

 parent carries the factor R. 



Further proof, were it needed, has been furnished by crossing two 

 plants each of some 372 apparently pure white races, which were under 

 single plant culture, by a pure pink. Of these, 82 have given an LP 

 or VL Fi, indicating that the white parent lacks the R factor; 279 have 

 given a, PW Fi, and of these the white parent is probably pure for the 

 R factor, while 11 have given a mixture of LP and PW plants indi- 

 cating parental impurity for the R factor. 



