6o4 



excrescent tissue (7c), it is found that this gradually dwindles away and 

 inside the bark bej^ins to take on a normal character (/;/.) Here the ar- 

 ranjjemcnt of the hard bast cords is still approximately normal but their 

 structure has been changed greatly. The majority of the bast cells ha\e 

 a yellow, swollen content and easily browned walls. Nevertheless, they 

 are distinguished, as strong, light-colored groups from the deep brown bark 



Fis". 143. First stases ot the rose cankei-. 



parenchyma which is cut off from the outer coUenchymatous bark layers 

 f)y the suljse(|ucnt]y produced layer of plate cork {k'). 



The drawing shows, however, that the ring of bast cells (^) is removed 

 farther from the wood body the further it advances into the tissue of the 

 excrescence. It is, therefore, pressed away from the wood body by the 

 increase of this body. At the same time the bast ring is seen to have been 



