284 Principles of Plant Culture. 



Other means of using the apparatus shown in Fig. 

 173 will occur to the thoughtful teacher. It may be used 

 for determining specific gravities by dividing the weight 

 by the volume. 



Germination (28). Give an exercise in testing seeds 

 with the apparatus shown in Fig. 6. 



Moisture essential to germination (29). Soak one lot 

 of navy beans in water until they are fully swollen and 

 another lot until they are about half swollen. Wipe the 

 beans as dry as possible, put each lot into a bottle, cork 

 the bottles, and set them in a warm room. The fully- 

 swollen beans will usually germinate promptly, while the 

 others will not. 



Oxygen essential to germination (31). Perform the 

 saucer experiment as described. 



Also place seeds of rice in two bottles, and add to 

 each, water that has been boiled 20 minutes ; cover the 

 water in one bottle with a little olive or cotton-seed oil. 

 It is important to soak the seeds a short time in boiled 

 water before putting them into the bottles to remove 

 the air in contact with their seed-cases. 



Ci'mination hastened by soaking seeds (35). Soak 

 I . ids of Indian com two or three hours in warm water, 

 and let each student place in a seed tester a sample of 

 the soaked seeds, with one or two other seeds of the same 

 kind that have not been soaked. 



Germination hastened by mutilating the seed-case 

 (36). This may be illustrated with seeds of the navy 

 bean, in the seed-tester. 



The plantlet (40). Place seeds of radish, onions, etc., 

 loosely on the surface of a saucer filled with fine moist 

 loam; keep the surface moist and note the repeated at- 

 tempts of the hypocotyl to enter the soil. 



Seeds of the pumpkin family should be planted flat- 

 wise (42). Plant seeds of the pumpkin or squash, in 

 the three positions indicated, in large greenhouse sau- 

 cers. Cover each saucer with a pane of glass and 

 place all in a warm room until the plantlets appear, 

 after which note the number of each lot of seeds of 

 which the seed-case appears above the surface. 



