30 Colour and other Characters in the Potato 



employed in the Mendelian analysis by Bateson, Miss Saunders and 

 others, all potatoes possess the factor C. Miss Wlieldale, who has 

 very kindly examined many of my tubers from this point of view of 

 pigment analysis, confirms this view. If, then, colour can be present 

 in the haulm and even in the shoot and still not be developed in 

 the tuber, it would seem that there must be some factor which acts 

 as a " developer " of pigment, and in its absence the tuber is white 

 (yellow). The supposition that this factor might be an inhibitor of 

 colour is negatived by the fact that white are recessive to coloured 

 tubers. 



It is necessary now to observe how the potato plant behaves in 

 actual breeding experiments. 



The white potato breeds true. 



Several hundred, about 600 in all, of seedlings of " Bohemian 

 Pearl " and " Sole's Kidney," both white potatoes, were raised, and 

 all the plants that bore tubers at all carried white ones only. 



A " Bohemian Pearl " seedling was selfed and gave a half-dozen 

 white-tubered seedlings. 



A "Sole's Kidney" gave 800 white-tubered seedlings, and one of 

 these selfed and produced fifty seedlings, all of which were white- 

 tubered. 



A white-tubered variety (Z)) extracted from " Flourball " has been 

 bred now through three generations and gives rise to nothing but 

 white-tubered plants. 



The variety "Early Regent" sown this season has produced 125 

 white-tubered plants and none carrying coloured tubers. 



The Colour Composition of the Red Potato. If seedlings of 

 " Flourball " be grown and these, after harvesting, divided up in 

 respect to colour, it will be found that red-tubered plants are to 

 white as 9:7. 



The numbers in my experiments were : — 



1907 271 Red plants 217 White 

 June 1909 71 „ GO „ 



Oct. 1909 24 „ 19 „ 



Aug. 13, 1910' 54 „ 44 „ 



Total 420 „ : 340 „ 



Ratio 9 „ : 709,, 



1 There are still about 100 plants to be harvested. 



