242 DISEASES OF TREES 



of red deer in the forest district of Ramsau with a substance 

 containing bone meal, as well as with a special powder (Hofeld's) 

 consisting chiefly of phosphate of lime and oak-galls. It was 

 reported that the trees were not afterwards barked. Others 

 again believe that summer peeling is merely the continuance 

 of a mode of obtaining food which necessity taught the animals 

 during winter, and that game thus get into the habit of barking 

 during summer even when other food is present in abundance. 



On account of their periderm remaining smooth for a long time 

 up to the height of four or five feet, bark being formed only 

 comparatively late in life, the spruce and silver fir are longest 

 exposed to the danger of barking. In the case of these trees, 

 therefore, it often happens that barking is repeated after an interval 

 of several years (Fig. 139), and stems are not unfrequently to 

 be met with which show evidences of having been barked at 

 various ages as often as five times. 



As the Scotch pine and larch, especially the former, produce 

 rough bark early in life, they are exposed to the danger of 

 barking only for a short period. It is only that portion of the 

 stem of the Scotch pine which is from three to five years old 

 that is barked. The portions that are younger are protected by 

 the leaves, and those that are older by the thick bark. 



The damage which results from barking varies with the spe- 

 cies of tree, time of year, and dimensions of the wound. The 

 resinous pine suffers but little, unless the stem is completely 

 barked round. The exposed wood dries and becomes so 

 abundantly impregnated with turpentine and resin that further 

 decomposition is prevented, and evaporation of water from the 

 internal layers is retarded. The wounds, however, close with 

 great difficulty, because the coalescence of the callus-cushions 

 is interfered with by the early formation of rough bark 

 (Fig. 138). 



The spruce, on the other hand, suffers much more from 

 barking, partly because it is not usually attacked till a later 

 period of growth, when much larger wounds are formed, and 

 partly and more particularly because the wounded surface is 

 not impregnated with resin to the same extent as in the case of 

 the pine. Less damage is done by barking during winter than 

 during summer, not only because in the former case the wounds 



