94 PHYSIOLOGICAL PROCESSES IN PLANTS 



Observations. 1. Which tube shows the greatest change in 

 level ? 



2. Which test was successful, for the starch or for the 

 sugar ? 



Conclusions. 1. Which substance was able to pass through 

 the membrane ? 



2. Which one of the two is already soluble ? 



3. How might you change (digest) insoluble starch to soluble 

 sugar? (See experiment, digestion in the corn grain, Prob. 

 X.) 



4. In what form must insoluble starch pass back and forth 

 through the stem, and from cell to cell through cell walls ? 



f. How Stems protect Themselves (Optional) 



Fill in the above table with as many plants as you can find that protect 

 themselves as indicated at the top of the columns. Write a paragraph, 

 summing up the information tabulated. 



Questions 



1. What are the uses to the plant of each of the parts 

 shown in a cross section of a woody stem ? 



2. Where is the upward and downward path of liquids 

 through a woody stem ? Of a pithy stem ? 



3. What is the condition of food as it passes through the 

 stem ? 



4. Mention some special uses to man of stems. 



5. What is meant by grafting ? Budding ? 



6. What are some of the methods of cutting timber ? 



7. What is the function of fibrovascular bundles ? 



