VEGETABLE PLANTS. 35 



keep it too cool to produce good tubers. With 

 the above system of cultivation, and a selec- 

 tion of early varieties, we believe that the 

 sweet potato is capable of being grown with 

 profit even as far north as central and western 

 New York. A soil containing a large pro- 

 portion of coarse gravel-stones, with a general 

 tendency to sandiness, we have found far pref- 

 erable for growing good specimens of sweet 

 potatoes to one whose base is clay. 



