42 PLANT BIOLOGY 



4. In which direction, therefore, will there be the greater 



movement of liquid in the process of osmosis ? 



5. How, then, is a root-hair adapted by structure for 



absorbing soil-water? 



C. Roots as organs for transmitting soil-water. 



Place some seedlings or weeds in red ink so that only the 

 lower ends of the roots are in the liquid. Cut some 

 cross sections of these roots above the point where 

 they were in contact with the ink. Examine the 

 cross section of the root prepared in this way. 



1. Describe the experiment as it was performed. 



2. Through what part of the root (cortex or central 



cylinder) has most of the liquid passed ? How do 

 you know? 



3. Make a sketch about an inch in diameter of the cross 



section of the root, to show the colored and colorless 

 portions. Label : part of the root through which 

 liquid traveled, unstained portion of root, cortex, 

 central cylinder. 



D. Roots as organs for the storage of food. 



Cut some slices about an inch thick from parsnips or other 

 fleshy roots, and divide each slice vertically in 

 halves. Put the pieces in water and boil for a few 

 moments to partially cook them. Pour iodine 

 solution over some of the pieces; to others add 

 strong nitric acid ; boil still other pieces in a test 

 tube with Fehling's solution. 



1. Describe the preparation of each of the experiments, 



and state in each case your observations. 



2. What do you conclude as to the presence or absence of 



each of three of the food substances in various parts 

 of the fleshy root you are studying? 



3. What function of roots do these experiments demon- 



strate? 



57. Adaptations of roots for holding to the soil. One 



of the most obvious functions of roots is that of holding plants 

 firmly in the ground. If the soil is carefully removed from 



