40 Colour arid other Characters in the Potato 



standing out in the naidst of the blackened and diseased debris which 

 marked the site of their destroyed neighbours formed a very striking 

 picture. Successful crosses have been made this year between the 

 immune seedlings and domestic varieties. 



The Flower. It has been already noted that the flower of this potato 

 is of a very delicate lilac and that the pigment is on the under surface. 

 The petal is entirely self-coloured ; there is neither an intensification or 

 a weakening of the general tone in the central region of the petal, as 

 one so commonly finds in potato flowers. 



The flowers of the seedlings offer considerable variations. Of the 

 40 plants 20 flowered, and of these — 



Nine plants were exactly like the parent, i.e. uniform colouring on 

 under surface ; 



Two plants were similar to parent but double the intensity of 

 colour ; 



Three plants had the same general colouring as the parent, but 

 with a deep-coloured tongue in the middle of the petal, and in one it 

 was noted (probably true for all) that the colour in the tongue was both 

 in the upper and in the lower coats of the petal ; 



Three plants had white flowers with purple tongues in the centre 

 of the petal, the colour in the tongue being on the upper surface ; 



Three plants were pure white. 



The sequence of the diverse flowers can be readily explained on the 

 following hypothesis — that we have two pairs of characters at work — 



A. Colour. a. Colour absence. 



B. Uniform distribution of colour h. Distribution of colour in a 



on under surface. pattern on upper surface. 



We then get — 



6 : Bh. Aa. = Parent type. 



2 : Bb. AA. = „ „ with deeper-coloured tongue. 

 1 : AA. BB. = „ „ but deeper colour, 



S : A. b. = White with coloured tongue. 



3 : a. B. = White. 

 1 : ab. = White. 



The numbers are too small to lay much stress on an explanation 

 such as the one given, but the phenomena fall readily into line. 



