152 AGRICULTURAL BOTANY 



may be determined. The kernels in the first row at 

 the base of an ear of corn and those at the tip are likely 



FIG. 74. Sand Tray showing Corn Seven Days after Planting. 

 From Circular 96, Office of Experiment Station, U. S. Dept. of Agriculture. 



to be poor in germinating power, so they should be 

 rejected. (See page 150.) 



In general, it has been found that heavy, young, and 

 large seeds are the strongest seeds. 



Impurities in Seeds. --The seeds of ordinary farm 

 crops, except corn, are likely to be mixed with dirt, 

 seeds of weeds and other plants, chaff, dead seed, and 

 imperfect seed. The smaller the seed, the more likely 

 it is to contain some or all of these impurities ; thus it 

 is more difficult for the farmer to obtain clean, pure 

 clover and grass seed than clean, pure wheat and oats. 

 Cheap seed is likely to be the most expensive in the 

 end because the presence of part or all of these im- 

 purities will surely reduce the yield. 



Treatment of Seeds before Planting. - - Seeds are 

 sometimes soaked in water in order to soften the seed 

 coats and start germination. Seeds of many forest 

 and fruit trees are given a treatment known as strati- 



