IMPROVEMENT OF PLANTS 



165 



quently select their seed corn solely with reference to the grain and 

 the stalk. It is not a good plan to select the seed from corn in the 

 crib, as is frequently done, but it is best to go to the field and make 

 the selection from the growing stalks of corn. The plant must be 

 considered as well as its product. Not only must we have a good 

 ear of corn to select our seed from, but we must know that the stalk 

 on which it grew was able to produce more than one ear of the kind 

 that we use for seed. If we follow this plan from year to year, the 

 yield per acre will be increased, while the amount of work spent in 

 cultivation will be no greater. Not only shall we be able to increase 

 the yield, but we shall be able to produce new varieties. 



A notable instance of the effect of selection is seen in the develop- 

 ment of sugar beets. Some of the first beets that were grown 

 had only approximately 



8 per cent of sugar, but 

 by selecting each year 

 the seed from the sweet- 

 est beets a new variety 

 was finally developed 

 which had from 18 to 20 

 per cent of sugar. The 



test is made by insert- Dia ^ ram of increa se of sugar in beets produced by selection. 



ing a trier in a slanting direction from the shoulder of the beet and 

 extracting the core of the root. The juice of this core is analyzed, 

 and the beets showing the highest percentage of sugar are kept 

 for the production of seed. After removing the core the hole in 

 the root is filled with charcoal, clay, or cotton dipped in formalin 

 to prevent decay. Sugar production from beets dates back to 

 1747 in Austria in the Old World, but in the United States 

 continuous attempts have been made since 1863. California, 

 Colorado, Michigan, and Utah are our chief beet sugar producing 

 States. The total annual production of beet sugar is about two 

 hundred thousand tons. 



EXERCISES 



1. Plant a few radish seed in two tomato cans of sand. Label the cans 

 A and B. Keep both watered and supply B with fertilizers. Note results 

 and explain. 



2- Fill six match boxes or chalk boxes partly full with rich moist soil. 



