36 GROWTH AND WORK OF PLANTS 



to some of these soil particles are thus brought into very close con- 

 tact with the water film in the soil, and absorb it, while fresh 

 water is drawn through the film from the ground water below. 

 Where free soil water is present in the soil for any length of time 

 about the roots of most dry land plants, the plants become 

 sickly. Many plants, however, grow in soil where there is free 

 soil water continually, or for a great portion of the time. Ex- 

 amples are seen in the swamp plants, semiaquatics, etc. 



i 



