42 Colour and other Characters in the Potato 



Crosses with S. etuherosum and maglia. 



Sol. etuberosum x Sol. maglia (deep purple) 



One seedling white tuber. 



Sol. maglia x Sol. etuberosum. 



One seedling white tuber. 



Here again the " white " of etvherosum is dominant to the purple of 

 the recognized species maglia. 



The relation of S. etuberosvm to other potatoes. Although the name 

 " etuberosum " has been used in this paper, it has been done rather for 

 convenience than with any idea of establishing its identity with the 

 species described by Lindley. 



Whether S. etuberosum is to be classed with the domestic varieties 

 or as a native species is a question that may have an increasing import- 

 ance. It has been shown in this paper that in respect to such important 

 characters as shape, eye and colour of tuber it behaves in a diametrically 

 opposite way to the domestic varieties, and it is, therefore, likely that 

 it is distinct from them. On the other hand, its white is dominant to 

 the muglia purple, and its own purple is also recessive; so that in 

 respect to this character it certainly more closely resembles maglia. 



The flower of etuberosum is much smaller and more compact than 

 that of the domestic potato, and is much more like the wild S. etuberosum 

 and S. maglia, and its scheme of colour as described here has no parallel 

 amongst the domestic varieties. 



There would seem, therefore, to be no adequate reason at all for 

 classing S. etuberosum amongst domestic varieties ; on the other hand, 

 it has certain characters akin to those of recognized specific types, such 

 as S. maglia. 



It has been suggested that the diversity of the S. etuberosum 

 seedlings shows it clearly to be a hybrid. That may be, but we can 

 feel at least equally sure that its parents are not domestic varieties. 



Conclusions. 



Very briefly the following conclusions have been reached in this 

 paper. 



Domestic Varieties. 



1. The twist of leaf, as seen in " Red Fir Apple," is a recessive 

 character. 



