54 Introduction to Botany. 



tumbler or wide-mouth bottle containing a weak solution of 

 fuchsin, and keep the roots covered with this solution until 

 a red color appears in the veins of the leaves. The stain 

 will color the tissues through which it passes and thus 

 mark out the paths of the ascent of water. Balsam stems 

 are sufficiently transparent to allow the tissues near the 

 center to be seen from the outside. 



70. Remove a ring of bark about an inch long from 

 some twig or sapling which is in leaf (the willow serves 

 excellently for this and the following experiment because 

 its bark is strong and easily separates from the wood), and 

 note whether the leaves wither. Watch the experiment 

 for several days. Operate on another twig or sapling in 

 the following manner : Make a longitudinal incision 

 through the bark an inch or more long, depending on the 

 diameter of the stem, and then, with a thin, smooth stick 

 work the bark loose around the stem, inserting the stick 

 through the longitudinal slit. Cut the wood of the stem 

 nearly in two, and then bend the stem until it breaks, 

 the broken ends protruding through the slit in the bark. 

 Trim off the ends so that they will not touch each other ; 

 then hold the stem upright so that the ends are again cov- 

 ered by the bark, and bind splints around the outside to 

 keep them in place. Care should be taken during this 

 operation that the bark is not injured except by the longi- 

 tudinal slit. Note the effect on the leaves in the course of 

 a few hours. What do these experiments teach as to the 

 region of water ascent in plants ? 



71. Remove a ring of bark from a branch or sapling 

 that can be conveniently watched, and note the result at 

 the end of the season's growth. What do the results teach 

 as to the region of transfer of food materials necessary to 

 the building up of new tissues ? 



