INJECTION KNPEnnrENTS ON Pr.ANTS. 



V. Injection into parenchymatous tissue. 



(Compare exp. 77-83.) 



For these experiments, we must choose plants with thick 

 parencliymatous tissue, so that the injection may be performed 

 witli ease. Wlien injecting into tlae cortical parenchymatous tissue, 

 the needle was inserted as little as possible, nearly parallel to the 

 surface of that part, and then the solution was gently injected. 

 Injection into the medullary parenchymatous tissue often proves 

 difficult as it is necessary to expose a part of the pith by cutting 

 out some parts of the outer tissues (cortical tissues and vascular 

 bundles) with a sharp knife. The needle must be introduced deeply 

 into the pith and brought as nearly parallel as possible to the 

 axis of this ; then the injection should take place gently and with 

 great care, so as to avoid over- injection into other parts. For a 

 plant having a wide medullary cavity (e.g. Vicia Faba), there may 

 be no need of cutting off the outer tissues, since the medullary 

 air-space readily takes up the solution injected. In this case, insert 

 the tip of the cannula into the medullary cavity, piercing the body 



