86 THE PLANT: A GENERAL INTERNAL VIEW 



27. The Working Together of the Whole Machine. — 



Now perhaps you are ready to picture to yourself the 

 working together of the whole machine. Think of a seed, 

 and observe one as you think. With moisture and tem- 

 perature right, the protoplasm in the embryo becomes 

 active. It has been dormant long enough. The seed 

 absorbs moisture and swells. Its cells become turgid. 

 The old seed coats burst. The stored food changes its 

 nature. It is digested. It is dissolved by the entering 

 water, and moves toward the embryo, which begins to grow. 



The seed sprouts. One part of the sprout seeks soil 

 and water. It turns down. It is the root. The other 

 part seeks light and air. It turns up. It is the shoot. 

 By the term shoot we refer to all of the plant except the root. 



As the young leaves unfold and chlorophyll appears, 

 the tender root-hairs sprout, and begin to clutch the soil 

 grains. The great effort of the plant appears to be to 

 place its root-hairs favorably in relation to the soil and 

 its chloroplasts favorably in relation to the light. And 

 now the cells, whose growth unerringly placed root tip 

 where it belongs and green leaf where it belongs, stand 

 ready to be the paths of movement. The root-hairs 

 absorb water. The fresh, new chloroplasts absorb light 

 and air. The currents of delivery and exchange move 

 through the little plant. Its life as an independent organ- 

 ism has begun. 



It continues to grow. All day long it makes food. All 

 night long it grows, more rapidly than in the daylight, 

 unless it is too cold. Its internodes elongate. At the 

 nodes new leaves appear. At their axils new buds appear. 

 The buds expand into little branches. The branches ex- 

 pand and bear more leaves. Presently a little branch 



