436 BULLETIN No. 127. [August, 



factors of soil physics, soil fertility, cultivation and climate dur- 

 ing the growing period. 



2. Under like conditions of environment, variations in table 

 quality are shown as varietal characteristics due to heritable dif- 

 ferences in shape, composition and physical structure. 



3. These heritable differences can probably be used as a basis 

 for improvement in quality when originating new varieties. 



4. There are also variations in quality within a variety which 

 are* in large measure due to immediate external conditions. These 

 fluctuations obscure the heritable variations upon which improve- 

 ment depends. 



5. The question as to whether partial fluctuations of these char- 

 acters obey the same laws as individual fluctuations, and whether 

 temporary improvement can be made through their selection is yet 

 undecided. The truth of Johannsen's theory of the fluctuations of 

 "pure lines" would answer this in the negative. 



