1908.] 



IMPROVEMENT OF THE POTATO. 



425 



RELATIONS OF DRY MATTER AND QUALITY 



In the same manner as above, selections of potatoes of different 

 dry matter content were tested. As far as was possible tubers of 

 relatively the same weight were used, in order to have the same time 

 of cooking. Otherwise the selection was entirely by dry matter: 



TABLE 7. QUALITY AS RELATED TO DRY MATTER 



This table shows that there is a lower limit in amount of dry 

 matter or more probably of carbohydrates, below which tubers can- 

 not be of good quality. In this variety it is about 18 percent dry 

 matter or probably about 15 percent starch. 



When the dry matter is above this lower limit, the quality does 

 not seem to be directly affected. It may be that this lower limit is 

 different in different varieties, and that owing to the general low 

 dry matter of these samples the standard of quality was put too low. 

 However some excellent potatoes were found with a total dry mat- 

 ter as low as 19 percent. 



Waterstradt and Willner showed that in certain German varie- 

 ties those tubers with very high starch content were of coarse qual- 



