S. C. Harland 197 



The ^3. 



1. 17 blacks bred true (480 plants). 



2. 16 blacks segregated into black and buff in approximately the 

 3 : 1 ratio. 



Plants BUck Buff 



440 348 921 



Expected ... 330 110 



3. 14 blacks segregated into black and red in approximately the 

 3 : 1 ratio. 



Plants Black Bed 



382 284 98 



Expected ... 287 96 



4. 21 blacks segregated into black, buff, and red in approximately 

 the 12 : 3 : 1 ratio. 



Plants Black Buff Bed 



826 612 159 55 



Expected ... 619 155 62 



5. 8 buffs bred true (307 plants). 



6. 19 buffs segregated into buff and red in the 3 : 1 ratio. 



Plants Buff Red 



636 462 174 



Expected ... 477 159 



7. 11 reds bred true (420 plants). 



Interpretation of the cross Black by Buff. 



Two factors are involved in this cross, B, the factor for black, and N 

 the factor for buff. The factor R is common to both parents. The 

 cross is of the nature black (BnR) by buff(bNR). The types appearing 

 in .^3 are as follows : 



9BNR 3BnR 3bNR IbnR 



Black Black Bufi Bed 



The results of this cross demonstrate that factors B and N are 

 probably independently inherited, and that N is not essential for the 

 full production of black. 



It will be seen from the above summarised results that the ratios 

 obtained go far to confirm the hypothesis that two independently 

 inherited factors, B and N, are concerned in the cross black by buff. 



1 These numbers are somewhat far removed from expectation. In two families, Nos. 

 51 and 105, the number of buffs is abnormally small, being 2 out of 57, and 2 out of 47 

 respectively. It is possible that accidental mixture of seed has taken place. If these two 

 families are not counted, the ratio of black to buff is 248 : 88, with expectation 252 : 84 on 

 a 3 : 1 basis, 



14-2 



