The potato. 245 



deep and close cultivation after the tubers have begun 

 to grow often does harm. Keeping the soil free from 

 weeds and the surface loose are the points desired. 

 The implements used and the frequency of cultivation 

 differ greatly in different regions. 



Harvesting. — Potatoes may often be left in the 

 ground until there is danger of frost, but it is safer to 

 harvest them as soon as they have thoroughly ripened. 

 There are several machines for harvesting the crop, 

 which answer the purpose fairly well. Some simple 

 and low-priced ones are somewhat like a sub-soil plow, 

 with rods running back from the shovel, between 

 which the earth passes while the potatoes are carried 

 to the surface. Other machines are larger and more 

 complicated. 



In all cases the potatoes must be picked from the 

 ground and sorted by hand labor. The sorting is best 

 done in the field. The potatoes may at once be placed 

 in ]3arrels or boxes, in which .they are kept until sold, or 

 they may be stored in bins or pits in the ground. A 

 dry, cool place, with as little change of temperature 

 as may be, is essential to their best preservation, 



SWEET POTATOES. 



The sweet potato (Convolvulus batatas) L., is of un- 

 certain origin. Dr. Candolle gives the preference to 

 America, but admits the strength of the arguments in 

 favor of an Asiatic origin. It was taken from America 

 to the south of Europe by the Portuguese or Spaniards. 

 It is now largely grown in the warm climate regions 

 both in the new and old world. In parts of the 

 southern states it is more common than the white po- 

 tato. It can be successfully grown in the more 



