584 BOTANY OF CROP PLANTS 



touch the Canadian border. It is well adapted to elevation 

 up to 8,000 feet in the Central Rocky Mountains. Smith has 

 shown that the potato makes its best development in those 

 sections of the country where the mean annual temperature 

 is between 40° and so°F., and where the mean for July is not 

 over 7o°F. 



The plant is grown on both heavy and light soils, but the 

 latter are preferred; upon these, the plant is less subject to 



Fig. 238. — Percentage of the world's supply of potatoes produced in the 

 different countries in 1914. 



disease, the tubers are of better quality and smoother, and 

 come to maturity more quickly. 



Uses of Potatoes. — Potatoes are put to the four following 

 chief uses: (i) human food; (2) commercial starch; (3) stock 

 food; and (4) alcohol. Potatoes rank second to the cereals in 

 importance as a food of northern peoples. They are fed to 

 all classes of stock, especially hogs. In the dried state, they 

 have been fed, in Germany, to cattle and horses with good 

 results. 



Potato Starch. — The potatoes are first soaked for several 

 hours in water, then washed, and finally reduced to a pulp 



