548 



Journal of Agricultural Research 



Vol. V, No. 13 



Table II. — Percentage composition of halves of sweet potatoes kept for various times 

 under different conditions — Continued 



The results indicate that the longitudinal halves of sweet potatoes 

 which have been stored for a time are hkely to show a greater dissimi- 

 larity in composition than the halves of freshly dug potatoes. The dif- 

 ferences, however, are not sufficiently great to overshadow the significant 

 differences seen in the later tables. The inequality in composition of the 

 halves of the same potato is much less than the unlikeness of different 

 potatoes. The method of comparison of halves is therefore more satis- 

 factory than the comparison of different whole potatoes unless a suffi- 

 cient number be used to obliterate, to a great extent at least, errors due 

 to individual differences. 



The question whether the cut halves behave in the same way in Storage 

 as whole sweet potatoes can be more easily discussed in connection with 

 the data presented later. It should be mentioned here, however, that in 

 the first experiment at 15.5° C. the halves lost an unusual quantity of 

 moisture and that this drying may have had some influence on their 

 behavior. In subsequent experiments precautions were taken to avoid 

 a loss of moisture as far as possible. 



EXPERIMENTAL DATA 



The data relating to all the experiments are collected in Tables III, 

 IV, and V. Table III contains the data of the three experiments con- 

 ducted at 30°, Table IV those of the experiments at 5°, and Table V 

 those of the experiments at 15.5° C. Under each experiment the first 

 section refers to the changes in composition of the sweet potatoes during 

 the first period of 10 to 12 days immediately after the roots were dug, 

 while the second section gives the changes during a period of equal length 

 immediately following. The change during each period is shown by the 

 difference in composition between the "a" halves analyzed at the begin- 

 ning of their respective periods and the "b" halves of the same potatoes 

 analyzed at the ends of the periods. The data in each case are based on 

 the water content of the first half of the potato analyzed. The columns 

 of differences show, respectively, the difference in the percentage of 



