PHYSIOLOGICAL PROCESSES IN PLANTS 67 



nated. When all have germinated that will, subtract the number remain- 

 ing from oiiQ hundred. 



Note. Suppose 20 seeds out of the 100 failed to germinate. Of course 

 80 germinated, or 80% of the sample. This is known as the percentage 

 of germination. This may be calculated with 50 seeds, but the likeli- 

 hood of error will be greater. Why? 



FIG. 12. Simple seed tester. 



Observation. Place 100 radish or clover seeds in a home-made 

 tester. Remove those that germinate from time to time. How many 

 remain ? 



Conclusions. 1. What is the percentage of germination of the seeds 

 tested ? 



2. Why is it especially important that seeds, as clover, be tested for 

 percentage of germination before planting ? 



Given several kinds and grades of any certain sort of seed on sale, how 

 would you finally decide on which to buy ? Should high-priced seeds be 

 tested before or after buying ? 



Note. Very valuable aid may well be rendered neighboring farmers 

 and gardeners by pupils in thus testing seeds which are to be used for 

 crop raising. Peas, beans, corn, cucumbers, melons, oats, wheat, barley, 

 etc., as well as the common garden seeds, may thus be easily tested. 



3. LARGE SEEDS VERSUS SMALL SEEDS 1 



Observations. 1. Plant a few beans an inch deep in jar 1; a few 

 clover seeds an inch deep in jar 2, the same number of clover seeds a 

 quarter of an inch deep in jar 3. Set them aside in good growing sur- 

 roundings, and note results daily until the seedlings are well developed. 



2. Compare jars 1 and 3. Which plants develop the more vigorously? 

 Which pushed through the greater amount of soil. Which seeds are the 

 larger ? 



1 Adapted from Goff and Mayne, First Principles of Agriculture. 



