6 N. H. Experiment Station 



a sample for production purposes cannot be greater than 

 the product of the actual percentage of purity multiplied 

 by the actual percentage of germination. For instance. 

 in the case of a sample of unhulled red top, guaranteed 

 50 per cent purity and 90 per cent germination, the real 

 seeding value of the sample is .50 x .90, or 45 per cent 

 (not 90% as might be assumed from looking at the 

 germination only). In other words, 45 per cent of the 

 weight of that sample is live seed, the rest is inert matter 

 or dead seeds. Likewise, in the case of a sample of 

 alsike clover, guaranteed 91.15 per cent purity, and 87 

 per cent germination, the actual seeding value of the 

 sample is .9115 x .87, or 79 per cent. 



A certain amount of variation is to be expected in 

 comparing the results of two or more purity analyses. 

 For this reason a "tolerance" or difference is allowed 

 between the average results of our tests and the guaran- 

 tee in accordance with the following formula. The 

 sample is considered as made up of two parts, the one 

 being the pure seed and the other the balance of the 

 sample. The tolerance in per cent allowed for the larger 

 part or pure seed is two-tenths of one per cent plus 20 

 per cent of the lesser part. For instance, if a sample is 

 guaranteed 99.60 per cent pure seed, it may test as low 

 as 99.32 per cent or as high as 99.88 per cent, come 

 within the "tolerance," and be "satisfactory." In the 

 same way, a sample guaranteed 92.80 per cent may test 

 as low as 91.17 per cent or as high as 94.43 per cent and 

 be "satisfactory." If a sample is found to be better 

 than the highest figure in the tolerance, it is marked 

 "above" in this bulletin ; if lower than the lowest figure, 

 the actual figure is reported. 



