122 TRANSPORT OF WATER AND SOIL SOLUTES 



9. To map out the course of water ascent in a very vivid way 

 place a young shoot of balsam or Ricinus into a weak solution 

 of eosin. If the plants have been crowded in the seed-bed so 

 that the stems are spindling and colorless, all the better for this 

 experiment. After a while in the balsam stems the stain can 

 be seen from the outside ascending the vascular bundles, and 

 later extending into all the fine ramifications of the veins. Cross 

 and longitudinal sections of the stem now show that the tracheal 

 elements alone are stained, and a leaf cleared in 5 per cent, 

 hydrochloric acid followed by saturated chloral hydrate will 

 show the tracheal elements stained. Of course if the stems 

 have been left long in the eosin this will diffuse from the tracheal 

 to the surrounding tissues. 



