182 COLLEGE BOTANY 



end of which is cut obliquely and submerged. Into the other hole fit an 

 L-shaped glass tube, but with end not submerged. Fasten a rubber tube 

 onto the outer end. Make a partial vacuum by sucking the air out. Note 

 the rise of bubbles from the lower end of the plant. Explain. 



Repeat, using a stem in winter condition. 



Exercise 5. Guttation. Put growing seedlings of cabbage, wheat, oats, 

 corn or other plants under large bell jar. Note the drops of water on the 

 tips of the leaves. 



Exercise 6. Collect some of the guttation drops on a clean slide. Allow 

 to dry and examine under the microscope. Does guttation water con- 

 tain salts? 



Exercise 7. Place freshly cut growing shoots in a solution of eosin. 

 (The shoots should be cut under water.) Examine from time to time and 

 note the rise of color. Cut thin sections and examine under the micro- 

 scope. Through what part of the stem does the color rise? 



