CHAPTER II. 



THE ROUND OF PLANT LIFE. 



The earliest stages of plant growth occur in the seed, 

 hence this is an appropriate place to commence oiir 

 study. We will first consider 



Section I. The Behavior op Seeds Toward Water. 



26. Seeds Absorb Water when placed in contact with 

 it. If we fill a bottle with air-dry beans, then pour in 

 all the tepid water the bottle will contain, taking care 

 to shake out the air bubbles, and place the bottle in a 

 warm room, the beans will soon swell until they have 

 pressed each other quite out of shape, and no water 

 A\ill be forced out of the bottle. This shows that the 

 beans have absorbed the Avater and have swollen in con- 

 sequence. This quality of absorbing water by contact, 

 at ordinary temperatures, is possessed to a greater or 

 less extent by most seeds, and indeed by nearly all air- 

 dry vegetable material. It is unnecessary that the seeds 

 be covered with water to enable them to absorb it. If 

 in contact with any moist medium, as a damp cloth or 

 damp earth, they mil absorb moisture and swell. 



27. The Rate at w^hich Seeds Absorb Water depends 

 upon several conditions, as 



a — The ivater conicni of the medium with which they 

 are in contact. If we place one lot of beans in water, a 

 second in wet earth and a third in slightly damp earth, 



(22) 



