228 THE LARCH. 



in the middle-aged tree another, and in the old tree 

 another. 



The dry, callous, inert matter, apparently of no 

 great use, serves the very important purpose of pro- 

 tecting both the liber or inner bark, and the cambium 

 or new-formed wood underneath, from the vicissitudes 

 of the weather. The bark appears to affect in a 

 wonderful manner the exhalation, inhalation, and 

 elaboration of the sap with the gases, which in other 

 and even the same plants at an earlier period are 

 affected through their leaves. A wound through the 

 cortical layers of a young plant heals without a scar, 

 but a wound through those of an old one is never healed. 



The larch, like any other tree, is liable to accidents 

 and diseases of various kinds, and to certain accidents 

 and diseases from which other species are exempt. 

 Some of the most common and serious diseases to 

 which the larch is liable are ulcer, blister, or bleeding 

 from wounds, which occur in the stem and bark; 

 ground-ovt, heart-rot, which commence in the central 

 part of the root and ascend into the stem or trunk 

 of the tree ; and disease of the foliage. 



The ULCEROUS DISEASE, which occurs in the bark of the 

 stem, manifests itself at every stage of growth, till the 

 trees are of considerable size and age, and the bark well 

 corticated ; sometimes it occurs in the nursery lines and 

 sometimes on plants only a few years in the forest. It 

 makes its appearance first upon the tender bark of the 

 tree, and is evidently the result of several causes, such 

 as confinement, superabundance of moisture, cold, wet 



