36 THE LARCH CANKER 



When part of the cambium has been destroyed, the rest 

 makes up for the loss by greater activity, and opposite 

 a canker the wood is abnormally thick, and the whole 

 stem may bulge in a curious fashion. The same may happen 

 at the sides as well, so that when one looks the canker full 

 in the face it appears to be set in an especially broadened 

 part of the stem (figs. 13 and 14). 



All the cells in the neighbourhood of a canker form large 

 quantities of resin, which permeates all the tissues. This 

 gradually oozes out through the shrivelled cortex and 

 phloem, and losing its more volatile constituents on exposure 

 to the air, hardens into large whitish drops. Such large 

 quantities are often formed that it runs down a stem in 

 streams, covering the bark for several feet. 



