90 



ROOTS 



Select seedlings whose roots are about \ or f of an inch 

 long, and place them as in a so that the root will project 

 outward. 



Stand the whole apparatus in a shady place for a day or 

 two and then examine it. Account for this change of posi- 

 tion in the root. 



Note. Sachs has shown the turning towards water (hydro- 

 tropism) by an experiment like the following. 



80. ROOTS 

 Object. Same as in Experiment 76. 



Method. Prepare a box with a wire-netting bottom. An 

 ash sieve will do very well. Scatter sprouted peas all over 



the netting. Fill the 

 sieve with wet sphag- 

 num moss or other 

 similar substance and 

 suspend it in an ob- 

 lique position. The 

 roots which project 

 downward will soon 

 show a tendency to 

 bend upward towards 

 the wet moss. 



They will frequently 

 be found weaving themselves in and out among the wires of 

 the screen. 



The root seems to be endeavoring to obey two influ- 

 ences: one, geotropism, which draws it earthward; the other, 

 hydrotropism, which causes it to turn towards the water 

 supply. 



FIG. 30. 



