CHAPTER XL 



V PATH OF MOVEMENT OF LIQUIDS IN PLANTS. 



105. Course of the liquids through the stems. — In our study 

 of root pressure and transpiration we have seen that large quan- 

 tities of water or solutions move upward through the stems of 

 plants. We are now led to inquire through what part of the 

 stems the liquid passes in this upward movement, or in other 

 words, what is the path of the " sap " as it rises in the stem. 

 This we can readily see by the following trial. 



Demonstration 20. 



106. To show the tracts through which the liquids rise. — Cut off leafy 

 shoots of various plants and insert the cut ends in a vessel of water to which 

 has been added a few crystals of the dye known as fuchsin to make a 

 deep red color (other red dyes may be used, but this one is especially good). 

 If the study is made during the summer, the "touch-me-not" (impatiens) 

 will be found a very useful plant, or the garden balsam, which may also be 

 had in the winter from conservatories. Almost any plant will do, however, 

 but we should also select one like the corn plant (Zea mays) if in the 

 summer. 



107. These solutions color the tracts in the stem and leaves 

 through which they flow. — After a few hours in the case of the 

 impatiens, or the more tender plants, we can see through the 

 stem that certain tracts are colored red by the solution, and 

 after 12 to 24 hours there may be seen a red coloration of the 

 leaves of some of the plants used. After the shoots have been 

 standing in the solution for a few hours, if we cut them 

 at various places we shall note that there are several points in 

 the section where the tissues are colored red. In the impatiens 



61 



