154 TEXTBOOK OF PLANT PHYSIOLOGY 



of such substance or even by placing the roots of the plant in 

 the solution. It is necessary to open the conductive system and 

 to let the solution directly into the cut vessels. Nutritive sub- 

 stances may be introduced in the same way, as for instance iron 

 salts in the case of chlorosis. In order to inject solutions into 

 a tree in this radical way, a funnel may be fastened to the tree. 

 An opening is made penetrating the bark and part of the wood. 

 Through this opening the solution is absorbed in unaltered con- 

 dition and soon reaches the leaf cells. Herbaceous plants also may 

 be made to absorb solutions in this extraordinary way. Espe- 

 cially adaptable for such experiments are plants with broad vessels, 

 such as the different representatives of the Cucurbitaceae. 



