118 Our Field and Forest Trees 



films, and so garden soil holds water which would 

 run quickly through sand or gravel. 



The little root-hairs act as if they were able 

 to understand their worlc and think about it. They 

 feel after the earth-water, hunt for It through 

 crooked places, and get enough for their needs in 

 soil which looks and feels quite dry. In groping 

 after this earth-water between sharp grains of 

 soil and sand the root-hairs, which were straight 

 at first, get bent, twisted, and flattened. 



The water that they absorb has in it some min- 

 eral matter, about as much as there is in ordinary 

 well-water. Besides this mineral matter, which 

 is already dissolved In the water films around the 

 grains of soil, the plant collects some for Itself. 



Root-hairs can get a little food off the hard sur- 

 faces of rocks or pebbles. This was proved by 

 an experiment. A layer of sand was spread over 

 a slab of porphyry, and seeds of several different 

 kinds were sown In the sand. Then slab, sand, 

 seeds and all were put Into a shallow dish, just 

 big enough to hold them and the sand-garden was 

 well supplied with water. In a short time the 

 seeds sprouted, and their little roots struck down 

 through the sand till they reached the porphyry. 

 They could go no farther In that direction. So 

 they turned sidewise and spread over the slab. 

 When the seedlings were turned out of their home, 

 and the porphyry was washed, lo and behold I 

 each finest rootlet had eaten off a little of the por- 



