THE MODERN POTATO PROBLEM < 229 



mum size of seed piece is reached, the vigour of the 

 sprouts becomes progressively less as the size of the 

 seed piece is further reduced. This minimum size for 

 many varieties has been found to be about 1.5 ounces. 

 The cause of the weak growth of sprouts on pieces of 

 tuber below a minimum size is not definitely known. 

 There are some indications that the potato tuber con- 

 tains a limited amount of an accessory growth- 

 promoting material. This may or may not be analo- 

 gous to the vitamine so essential to growth in animals. 

 Experiments have shown that seed pieces large enough 

 to contain an abundance of the usual nutrients for 

 sprout growth still produce weak sprouts. These seed 

 pieces lack something in sufficient amount to start 

 growth off normally. The plants from these weak 

 sprouts are correspondingly weak and the best of cul- 

 tural conditions will not revive their normal vigour. 

 During the recent war a prominent newspaper recom- 

 mended the planting of peelings and saving the rest of 

 the tuber for consumption. Valuable land and labour 

 werewasted by this practice. 



VARIETAL NOMENCLATURE. The ever increasing 

 number of so-called varieties has made the subject of 

 nomenclature for potato varieties an important potato 

 problem. More than five hundred names are reported 

 for varieties that are supposed to be still grown in the 

 United States. Much of the present confusion in 

 varietal nomenclature has resulted from the propensity 

 of seedmen to rename old varieties and to introduce 

 new varieties indistinguishable from existing ones. 

 This chaotic condition has been greatly improved by 



