i6 



Journal of Agricultural Research 



Vol. XII. No. I 



period the root is characterized by a high starch content, and a low sugar 

 content. The changes which occur later are associated with the death 

 of the vines. Prominent among these changes is the accumulation of 

 water in the roots as a result of the cessation of transpiration in conse- 



13/6. SEPT. 



OCTOBER 



NOVEMBER 



Fig. I. — Graphs showing changes in composition of Big Stem sweet potatoes during the latter part of the 

 season, from September i8 to November 27, and the minimum temperatures at the United States Weather 

 Bureau Observatory at Washington, D. C, some 20 miles distant, during that period. The ordinates 

 indicate percentages in the one case and degrees Fahrenheit in the other. 



quence of the destruction of the leaves. With the termination of the 

 flow of materials from the vines the carbohydrate transformations 

 characteristic of sweet potatoes in storage are inaugurated. These 

 changes consist in the transformation of starch into sugars. In point 



