R. N. Salaman 13 



but they do not admit of such definition as to fit them for Mendelian 

 analysis. 



The cross of " Red Fir Apple " and " Reading Russet " was made in 

 1906 for the purpose of tuber colour observations, and in 1909 a large 

 family of some 120 individuals of F^ plants were raised. 



The " Red Fir Apple " has a somewhat distinctive foliage, the 

 leaves are relatively small, ovate with sharp apices, peculiarly soft and 

 silky to the touch, and, in addition, have a character which entirely 

 distinguishes them from " Reading Russet " and most other varieties. 

 The leaf has a peculiar twist in its axis, this twist being seen in all the 

 upper leaves and often down to the lowest when the plant is 18 inches 

 high or more. 



The condition of leaf twist here in question must be clearly distin- 

 guished from that which occurs as a pathological condition in many 

 varieties ; in such cases the plants are dwarfed, the stems shrunken, 

 the axes of the branches very shortened, and the leaves on them 

 crowded together. The individual leaves also are much twisted, crenate 

 and small. 



In the "Red Fir Apple" the twist is less violent, it is not associated 

 with crenation, and the plants are thoroughly healthy, vigorous and of 

 good size. 



" Reading Russet " possesses a much coarser foliage, the leaves are 

 big, broad, blunt, flat, smooth, hard and coarse ; the green colour is of 

 a deeper shade than in " Red Fir Apple." 



The four F^ plants which were examined were intermediate as regards 

 shape and texture of foliage, but resembled " Red Fir Apple " shape 

 rather than " Reading Russet " ; no twist in the leaf axis was observed. 



In F- an analysis was made of the plant's foliage characters as seen 

 in the table below. 



The characters taken are all leaf ones. 



" Reading Russet " shape. Broad and blunt leaf. 



„ „ texture. Few stiff hairs, glazed surface to leaf. 



" Red Fir Apple " shape. Ovate, sharp apex to leaf 



„ „ texture. Soft and silky. 



Twist. Twist in the axis of the leaf. 



Intermediate shape. Leaf shape neither " Reading Russet " 



nor " Fir Apple " in type, but re- 

 sembling more closely the latter. 

 „ texture. Softer than " Reading Russet " and 



harder thau " Fir Apple." 



