1908.] 



IMPROVEMENT OF THE POTATO. 



421 



These results are in direct opposition to Condon's and Bous- 

 sard's as to nitrogen and starch but the discrepancy may have been 

 due to the different methods of determination. Nitrogen free ex- 

 tract gives total carbohydrates minus crude fibre, at all times, while 

 a direct starch determination is very different when made in the 

 fall from one made in the spring when large quantities of starch 

 have been changed to sugar. 



In 1901 Waterstradt and Willner (104) reported extended 

 investigations on the same subject. Their results are more appli- 

 cable to American conditions for the reason of similarity of stand- 

 ard of quality in Germany and America. Nine varieties were used, 

 each of which was grown on two separate fields. Of these varie- 

 ties, three were recognized to be of good table quality, three were 

 coarse starch producing varieties and three were on the border line 

 between the two. I give here the average composition only of the 

 first and second classes : 



This table shows that potatoes of better table quality are 

 markedly lower in starch than the others, as was to be expected 

 from the German classification. The dry matter in the cortical 

 layer is regularly higher than in the medullary layers, as is the 

 starch content when calculated to the fresh basis. When calculated 

 to the water free basis, however, the starch variations are slight. 

 The total nitrogen variations corroborated the results of Coudon 

 and Boussard. 



