32 



Genetic Studies in Potatoes 



esting to note that the family in which the greatest number of recessives 

 appear is Mb BSo, 23 x M5 BS2 x Fb 26 — a cross in which the male is of 

 the same kin as the " prostrate " female parent. 



The reciprocal cross gives identical results, the " upright " being 

 completely dominant. It is also of interest as being one of the very few 

 reciprocal crosses which have been effected in potatoes. 



The evidence thus far has shown that the " prostrate " character 

 behaves as a recessive. A considerable number of families were obtained 

 from Fi plants in the first or later years of their life, many of them from 

 protected flowers. Only one F^ was obtained from a " prostrate " x 

 " upright," and this showed no peculiarity. The results are tabulated 

 in Table V. 



TABLE V. 



F^ from Upright x Prostrate. 



Habit of Growth 



Serial No. Name of Family 



17 M, 76 a: 65 104 X EiJ 28 X ilf 5 B 35, 23 



59M, 17 Kew2xBR2xM5 B35, 23, 17 



74M, 18 Kew 19x£U 16xM5 £35, 1, 18 



UB, 2 „ X „ 2 



74ilf, 38 .. X „ 38 



Wliere Grown Method of Pollination Upright Prostrate 



Merton 



Barley 

 Merton 



By hand. Protected 

 Natural 



12 

 20 

 42 



28 

 26 



The first point to note is the very small number of " prostrates " 

 which reappear. As in F^ there was a large number of spreading plants 

 which in the field were occasionally difficult to distinguish from 

 " prostrates." Bfi such cases the anatomical test was applied with 

 decisive results. In a few plants slight defects in the development 

 of secondary wood were observed as in some of the ^i, but the true 



