R. N. Salaman 33 



seeing that on selfing it gives three red and one white. The results 

 were different in each case — 



H^ X A gave 29 red 19 white 



Jfi»x A „ 18 ,, 27 „ 



Total 47 „ 46 „ 



In either case it is possible that larger numbers would have shown a 

 nearer approach to equality. 



It must however be noted that the family H^" x A, had far less 

 pigment in its stem than H^ x A, and that the possible results of 

 mating whites with reds of .4's composition are equality, if the white is 

 rrDD or rrdd, or three red to one white if Rrdd. 



One other cross was made between a pale red and a white-tubered 

 plant. 



" Queen of the Valley " was crossed by a red seedling of " Flourball " 

 and the F^ generation consisted of seven red to three white. One of 

 these a pale red, 3I\ was crossed by a white seedling of the white 

 " Bohemian Pearl " B. Forty-one seedlings grew and 38 survived 

 to form tubers. Of these 



19 had red and 19 had white tubers. 



This result of equality suggests that the composition of the two 

 parents may have been — (AP) RrDd x (B) rrDD. M^ is probably 

 RrDd and not RRDD, RrDD, etc., because it is a particularly feeble 

 red and might therefore be assumed to have the least possible factors 

 that would give a red. 



Two reds, one very deep red, viz. " Red Fir Apple," and the other 

 a weak one, " Reading Russet," were crossed. " Reading Russet " has 

 now been selfed, and this year we shall learn its composition, but its 

 colour is weak like that of " Flourball," and it has probably the same 

 gametic composition, viz. RrDd^. " Red Fir Apple " is of a very deep 

 colour and might be RRDd. The F^ raised were 117 seedlings, but only 

 11 of them came to maturity, viz. eight red, and three white, indicating, 

 as would be expected from the union, a 3 : 1 ratio. 



RRDd X RrDd = 3 red : 1 white. 



Two plants arising both from tubers of the same individual of the 

 F^ family, viz. L> and L^, were selfed and produced in the F' generation 

 large families in which the ratio of red and white was 3 : 1. 



1 The 1910 seedlings of "Reading Russet," so far as yet harvested, are divided into 

 14 red-tubered plants and 10 white-tubered. 



Journ. of Gen. i 3 



