PERENNIAL FORAGE (IK ASSES 



minating power. On the other hand, a sample with the higher 

 percentage of viable pure seed may be less desirable to sow 

 because of the kind of impurities. 



14. Weight per Bushel. While the sale of seed by the hundred- 

 weight is gradually superseding sale by the bushel, nevertheless 

 weight per bushel is an 



excellent guide to the 

 number of seeds per 

 pound, since the freer 

 the seed is from chaff 

 the higher the weight 

 per bushel. In the 

 table on page 1 8 the ex- 

 treme variations in ac- 

 tual weight per bushel, 



Scales for determining the weight per bushel of seeds 



as reported by different 



stations and other authorities, are given in the first column; 

 while in the second column occurs the legal weight in Canada 

 and the several states where such legal standards exist. 



15. Impurities. These may consist of three classes: (i) inert 

 matter, (2) weed seeds, and (3) foreign but useful seeds. 

 Impurities may be accidental namely, due to the imperfection 

 of cleaning machinery and to the occurrence of weeds or 

 cultivated plants in the crop when harvested. Adulterants or 

 foreign bodies artificially added for gain may consist of inert 

 bodies such as colored stones in red clover seed, or seeds of 

 plants of greater or less usefulness but of less cost per pound 

 such as black medic seed in red clover, Canada blue grass for 

 Kentucky blue grass, and perennial rye grass for meadow 

 fescue seed. In some cases complete substitution is made. In 

 general, grass seeds have not been subject to a great deal of 

 adulteration. The purpose of many lawn grass mixtures, how- 

 ever, is to substitute lower priced for higher priced seeds. 

 Alfalfa and clover seeds have been rather more subject to 



