THE POTATO. 135 



few shillings to a few pounds per bag, depending chiefly on the 

 season. The best prices are obtained from July to October. 



Uses. — Apart from their use as human food and to a 

 certain degree as stock food, potatoes are used in the produc- 

 tion of starch, alcohol, glucose and syrup. Potato flour is 

 used largely in European countries as an ingredient in flour for 

 bread-making. 



Potato Improvement. — No discussion on this topic 

 would be complete without a survey of the chief factors in- 

 volved in the question of degeneracy in potatoes. It is the 

 experience of capable growers, in some localities widely 

 differing from the natural habitat of the potato, e.g., of high 

 temperatures, of low rainfall, and often at low altitudes, that 

 the importation of seed tubers is necessary because of the 

 depreciated productivity of old strains. 



There are many factors contributing to this state of 

 affairs ; chief among these are : — 



(1) The prevailing method of selecting the culls and small 

 tubers to be used for " seed " purposes. — In this method hills 

 of low productivity, and, although not apparent, often 

 diseased, receive disproportionate representation in the suc- 

 ceeding crop, consequently there is a constant tendency for 

 the crop to decrease in yield — colloquially " to run out." To 

 counteract this tendency, hill-selection should be practised 

 to obtain the high yielding biotypes (strains). The procedure 

 is to select healthy and vigorous plants in the growing crop, 

 and when dug to take the most productive and desirable hills 

 for propagation in a breeding plot. This is multiplied by suc- 

 ceeding plantings until sufficient seed tubers from these high 

 yielding hills are secured to plant the main crop. Hill-selec- 

 tion should always continue from the main crop, and the 

 breeding and multiplying plots maintained. 



That the yielding capacity of the hills in the same variety 

 differ widely is shown in the following experiments — viz. : 



