GERMINATION AND GROWTH 



37 



of wheat, oats, or barley before they are ready for harvesting. Try as 

 many kinds as you like, and see 'how many will come up. Notice whether 

 there is any difference in the health and vigor of plants raised from seeds 

 in different stages of maturity. 



EXPERIMENT 33. THE RELATIVE VALUE OF PERFECT AND INFERIOR 

 SEED. From a number of seeds of the same species select half a dozen of 

 the largest, heaviest, 

 and most perfect, and 

 an equal number of 

 small, inferior ones. If 

 a pair of scales is at 

 hand, the different sets 

 should be weighed and 

 a record kept for com- 

 parison with the seed- 

 lings at the end of the 

 experiment. Plant the 

 two sets in pots con- 

 taining exactly the 

 same kind of soil, and 

 keep under identical 

 conditions as to light, 

 temperature, and 

 moisture. Keep the 

 seedlings under obser- 

 vation for two or three 

 weeks, making daily 

 notes and occasional 

 drawings of the height 

 and size of the stems, 

 and the number of 

 leaves produced by 

 each. 



33. Resistance 

 to heat and cold. 

 In making experi- 



50 51 



FIGS. 50, 51. Stem development of seedlings: 50, 

 raised from healthy grains of barley ; weight, 39.5 

 grams (about 500 grs.) ; 51, raised under exactly similar 

 conditions from the same number of inferior grains ; 

 weight, 23 grams (about 350 grs.). 



52 53 



FIGS. 52, 53. Improvement of corn by selection: 

 52, original type ; 53, improved type developed from it. 



ments with regard to temperature, notice how the extremes 

 tolerated are influenced, first, by the length of time the 

 seeds are exposed ; second, by the amount of water contained 

 in them ; and third, by the nature of the seed coats. Every 

 farmer knows that the effect of freezing is much more in- 



