IMPROVEMENT OF THE POTATO. 



429 



Unfortunately this method cannot be used in selecting potatoes 

 for the table, on account of the necessity of their cutting. Whether 

 the extreme variations toward homogeneous structure are correl- 

 ated with quality to a sufficient degree to be used as a means of im- 

 proving varieties in quality; or whether fluctuations due to slight 

 environmental differences impossible to control, obscure the herit- 

 able variations, is now being investigated. There still remains the 

 possible explanation that the other factors influencing quality are 

 the causes of the great varietal differences, although our work in- 

 dicates that this is not probable. We hope that it will be possible 

 to use the method in determining the rejection of seedlings after 

 a cross. The tubers from the different first year plants should be 

 kept in different bags and at planting time selections made of those 

 tubers having a large cortical layer and a small internal medullary 

 layer branched in fine divisions, the idea being to have the in- 

 ternal structure of the potato as homogeneous as possible. 



FIG. 9. CROSS SECTIONS OF POTATO OF POOR QUALITY. SMALL CORTICAL LAYER AND 



LARGE THICK INTERNAL MEDULLARY LAYER. 



OTHER FACTORS INFLUENCING QUALITY 



i. Color of skin. Potatoes from seedlings of a single cross 

 varying in color of skin to white, light brown, pink and red did not 

 show any greater variation in quality than did those of a single 

 color. Hence it may be concluded that color is not correlated with 



