CHAPTER II. 



SEEDS AND SEEDLINGS. 



38. The Germination of the Seed. We have seen that 

 the Broad Bean seed contains a young plant and is covered by 

 a seed-coat ; that the young plant consists of an axis which 

 bears at one end (radicle end) a root- cap, at the other end 

 (plumule end) some young foliage-leaves, and at the middle 

 a pair of large seed-leaves ; that when the dry seed is placed 

 in water it swells up ; that when the soaked seed is planted in 

 moist sawdust or soil the seed-coat breaks open ; that the 

 radicle end of the young plant's axis grows down into the saw- 

 dust or soil and forms the root, and the plumule end grows 

 upwards into the air and forms the shoot, while the seed- 

 leaves remain in their original position ; that the young shoot 

 keeps for a time the hooked form which it has while inside 

 the seed-coat, but gradually straightens out as it grows up- 

 wards ; and that the young plant or seedling which arises in 

 this way gradually grows into a mature plant. 



The changes that occur, from the time the dry seed is placed 

 in water until the young plant establishes itself, are all included 

 in the term germination. The young plant in the dry seed is 

 alive but dormant, and the germination of the seed is simply 

 the awakening of the young plant to active life and growth. 



Broad Bean seeds (and those of most other plants) 

 germinate best when sown within a year of their ripening ; 

 the longer seeds are kept the fewer will germinate and the 

 feebler will be the growth of the resulting plants. Broad 

 Bean seeds will sometimes germinate after being kept for six 

 years. In other plants the seeds may remain alive for a 

 longer time, but the embryo, though dormant, is living and 

 therefore gradually losing substance by respiration, besides 

 losing water to the dry air around it. 



s. B. 17 2 



