THE STEM 



165 



menon the name of ' bleeding ' has been given. It was 

 thought to be the exclusive property of certain woody 

 stems, and to take place only at certain seasons of the 

 year ; this bleeding is specially profuse in the vine in 

 spring. Comparatively recent investigations have 



Fig. ^6. 



shown, however, that this phenomenon is common to 

 all plants, herbs as well as trees ; and that it takes place 

 all the year round, although certainly with very varying 

 intensity. In order to see this bleeding, and to measure 

 its force, the following method is used : a stem is cut 

 across not far from the ground, and we attach to the 

 stump, with the help of an india-rubber tube, a small 



