78 THE PLANT: A GENERAL INTERNAL VIEW 



of thin slices of tissues, stained, and magnified by the mi- 

 croscope. But they can give you little idea of the life 

 that goes on in these tissues. Nor can words give you 

 this idea very well. Life cannot be explained in any such 

 limited medium as language. Your own protoplasm has 

 powers which we cannot explain. So has a plant's. 



25. From Root to Leaf. — A plant stands at work. Its 

 roots are in the rich moist earth. Its leaves are bathed 

 by air and sunlight. Its cells are filled with the complex, 

 ceaseless workings of protoplasm. All its energies are 

 engaged in the great tasks of life. Always it strives to 

 sustain itself and to multiply its kind. 



The tender root-hairs cling closely to the soil grains. 

 Around each grain there is a film of water. (See Figure 28.) 



Fig. 28. — Diagram of root-hairs and soil. The clear spaces among the soil grains 

 indicate air. The lines of shading around the grains indicate films of water. 

 Note how closely the root-hairs are pressed to some of the soil grains. 



The smallest possible particles of some substances of the 

 soil are dissolved in the water. The root-hair draws 

 water away from the grains and into itself. The grains 

 renew the water film. Physical laws operate to keep mois- 



