I N. H. EXPERIMENT STATION. 



present, weed seeds, and inert matter such as diit, 

 hulls, stems, etc. Each part is carefully weighed on 

 analytical balances to determine the percentage of the 

 whole which it represents. A report is returned to 

 the dealer from whom the sample was taken and in- 

 dicates clearly whether the seed which he is selling 

 conforms to the guarantee in regard to the percentage 

 of pure seed. 



The pure seed is subjected to further tests in 

 regard to its viability. It is placed in incubators, 

 usually in duplicate groups of 100 seeds each, and kept 

 on moist blotters, cloths, or similar suitable material, 

 in an atmosphere saturated with moisture and care- 

 fully controlled as to temperature. With many seeds 

 a daily change of temperature is required varying from 

 68°F. to 86°F. Many different means have to be re- 

 sorted to in order to make the environment most con- 

 genial for the seed to gi"ow, but all methods employed 

 ai*e standardized and prescribed by the Association of 

 Official Seed Analysts, which is a nation-wide organiza- 

 tion of considerable insight based on many years of 

 research work with seeds. The results of such in- 

 cubation after a definite length of time, varying with 

 the kind of seed from four days to twenty-eight, are 

 observed and recorded as the germination. If the 

 two or more duplicate samples run together do not 

 show similar results for any reason, the tests are re- 

 peated. This report accompanies the purity test and 

 shows the dealer that the seed germinates as guaran- 

 teed or otherwise. 



Seed which does not conform to its guarantees 

 must be relabeled. Certain allowances are made, how- 

 ever, due to the fact that nature and human effort 

 always evidence some variation. Discrepancies of 6 

 to 10 per cent in germination may be accepted depend- 

 ing on how nearly perfect the seed is guaranteed to be. 

 In judging purity, the sample is assumed to be made up 



