84 APPLIED BIOLOGY 



As we shall see in later studies, the seed-coat is lost as the 

 embryo develops; it is therefore simply a structure for 

 protecting the embryo after the seed is out of the pod and 

 until germination is completed. 



81. Germination or Awakening of Seeds. A dry bean 

 seed shows none of the usual signs of being alive; but it 

 soon revives when placed under proper conditions (with 

 moisture, heat, and oxygen from the air), and rapidly grows 

 into a young plant (called seedling, or plantlet). This 

 " awakening " or reviving and growth into a new plant is 

 commonly called germination; and the seed is said to ger- 

 minate. The popular word " sprouting " usually means the 

 early stages of germination. 



Germination of Beans. (L) Beginning about two weeks before 

 this exercise, some beans should have been planted every other day 

 in soil (preferably in small boxes or flower-pots which can be taken 

 to the schoolroom). Plant about two inches deep, and keep the soil 

 moist and warm. Plant a few beans four, five, and six inches deep, 

 and some near the soil surface. Mark the position of these with 

 wooden stakes on which figures have been written with lead-pencil. 

 When some .young plants (seedlings) are two inches above the soil, 

 and others just emerging, the materials are ready for the following 

 lesson. 



Without pulling up any plants, carefully examine and compare 

 the various stages in order to determine where the parts of the 

 embryo seen in the seed are located in the seedling. What becomes 

 of the seed-coat ? The first joint or node of the stem is where the 

 cotyledons are attached ; the second at the leaves of the epicotyl. 

 Does the internode between these two nodes lengthen? Do the 

 cotyledons of the bean become leaf -like ? Compare the size and 

 shape of the leaves of the epicotyl with those you have seen on a large 

 bean plant. 



Make a series of sketches showing stages in the emergence of the 

 seedling from the ground. Leave space in note-book for adding 

 other and larger sketches of later stages as the plant develops for 

 several weeks. 



In order to find out what happens between the time the seed is 

 planted and the seedling emerges from the soil, we must either dig 

 up seeds planted at various periods of time or we must study these 



