14 Colour and other Characters in the Potato 



Foliage of F"^ Generation. 



" Reading Russet " texture. " Reading Russet " shape 10 



„ „ „ Intermediate shape 1 



Intermediate texture. " Reading Russet " shape 4 



„ „ Intermediate shape 40 



" Fir Apple " shape 12 



" Fir Apple " texture. Intermediate shape 9 



„ " Fir Apple " shape 42 



11 



Total number of J^2 plants .... 118 

 Twist in leaf 27 



In considering these figures it must be remembered that it is a 

 matter not only of considerable difficulty to classify the living plants 

 according to the shape and texture of their leaves, but that the 

 personal element is paramount in such a classification. More particu- 

 larly do such remarks apply to the consideration of texture and to the 

 intermediate forms. Certain features, however, are readily and unmis- 

 takably recognized ; these are the twist in the axis of the leaf and to a 

 lesser degree " Reading Russet " shape. 



The intermediate form of leaf is much more like the " Fir Apple " 

 leaf than the " Reading Russet," and the former may therefore be con- 

 sidered dominant, whilst the twist in its leaf is recessive. 



If the " Reading Russet " shape and texture are recessive, then it 

 should occur combined in the F^ family in the ratio of 1 : 15 and here 

 it is 1 : 12. 



The twist in the leaf occurred 27 times out of 118, that is practically 

 in the ratio of 1 : 3, and it was associated 23 times with the " Red Fir 

 Apple" shape, the remaining four having intermediate shapes and none 

 showing " Reading Russet " shape. 



Allowing again for the difficulty in distinguishing the intermediate 

 form from " Fir Apple " shape and texture, it would seem to be a fact 

 that this peculiar twist in the leaf is definitely linked up with the 

 " Fir Apple " characters of shape and texture. None of the eleven 

 plants possessing " Reading Russet " shape showed the slightest sign of 

 a twist. The same consideration leads one to believe that " Reading 

 Russet" texture is coupled up with "Reading Russet" shape; ten out 

 of eleven times it is recorded as being so linked whilst the eleventh 



