SYSTEMATIC SELECTIONS 285 



forms appearing suddenly from an old established form for ex- 

 ample, a white potato in a hill of red variety,, or a long potato in a 

 hill of round variety. Such sudden appearances of new types are 

 recorded and have been preserved, giving us new varieties. 



Systematic Selections. Plant breeding is simply a systematic 

 way of finding the small variations, either for better 'or worse, that 

 are constantly taking place. For example, if 100 potato tubers be 

 selected and each planted in a separate hill, it will be found at harvest 

 time that certain tubers have produced two or three times the yield of 

 others. The difference is to a large degree hereditary, so if the 

 highest yielding hills are saved for seed, a more productive stock is at 

 once secured. This practice of planting a certain number of tubers 

 separately and selecting only the best producing hills may be con- 

 tinued from year to year with gradual improvement. It is best 

 to use rather large tubers and cut each into four parts, as four 

 hills from each will give surer results than to have only one hill 

 from each. 



Outline for Describing Potatoes 

 Variety: 



1. Early, medium, late. 

 Shape : 



2. Oblong, round, oblong-flat, oval-round, oval-flat. 



3. Regular, irregular. 

 Size: 



4. Large, medium, small. 



5. Uniform, not uniform. 

 Eyes: 



6. Deep, medium, shallow. 



7. Oval, narrow, elongated. 



8. Large, small (as compared with size of tuber), 



9. Numerous, medium, few. 



10. Uniformly distributed, mainly at bud end. 



11. Ridge prominent, ridge not prominent. 

 Sprouts : 



12. Color yellowish- white, pink, blue, purple. 

 Skin: 



13. Smooth, rough, netted, lenticelled. 



14. Color yellowish-white, light russet, dark russet, red, pink, blue. 

 General Characteristics: 



15. Sample, clean, dirty. 



16. Cracked, not cracked. 



17. Disease present, disease absent; if present, scab, dry rot or blight; 



rhizoctonia, sunburn, grub, or wilt. 



18. Bruised or not bruised. 



19. Mature, immature. 

 Flesh : 



20. White, yellowish, pink. 



