176 WOUNDS AND INJURIES TO FOREST TREES. 



Fissures or longitudinal cracks extending deep into the trunk. Our 

 spruce {Abies nigra) is sometimes made worthless from this cau-^e. The 

 general opinion is that these cracks are caused b^' unequal contraction 

 by cold or from the twisting of the winds, or from intense solar heat. 

 The}' have been produced artificially by bending and twisting young 

 trees as thoy are served by violent winds, or when loaded with snow 

 and ice. 



Concentric o-acl's (cup-shake). — The layers of wood for a part or the 

 whole of the circle may be loosened ; sometimes in old trees to such 

 di'gree that the core will fall out of a block cut across the grain. These 

 loose seams are sometimes marked b^' lines of a dark-colorpd fungus. 

 They injure the wood for construction, are apt to admit moisture, and 

 become the beginning of decay. They are deemed the effect of acci- 

 dent rather than disease, and may show no sign of their presence till 

 the tree is cut. 



Where the bark is loosened by any cause, as frost, the movement of 

 winds, a violent blow, &c., a layer of wood may form under the bark, 

 but there will be a solution of continuity with the previous layer, and 

 so a concentric crack to the extent of the injured parts will remain ever 

 after. It has been observed that reserves left in a coppice are more 

 liable to this accident, as well as trees that grow in the open air. 



Where the bark is removed nature seeks to cover up the exposed 

 wood, and finally will do so completely if the task is reasonable. The 

 tree may finally show no external trace of the accident, but the dead 

 (perhaps not decayed) wood thus covered has no connection with the 

 uew covering, and the spot is wore or less defective when afterward 

 worked. 



Rotten sinuses. — A dead branch admits water, and this, following down 

 the fibers, may cause a rotten burrow, perhaps, of limited sectional area, 

 but extending a long distance down the trunk. It is one of the causes 

 of hollow trunk, so very common in the basswood, sycamore, and some 

 other kinds of timber when they get large and very old. In fact there 

 are few deciduous trees exempt f'rom the infirmity ot age, and it is a sale 

 rule to cut such timber as soon as this condition is known, and the sooner 

 the better. There are various kinds of discoloration liable to occur in 

 the interior of trees, which have received distinct names among foiesters. 

 It is sufiicient here to remark that they are mostly signs of inci{iient 

 decay, and that they more or less impair the value of the wood accord- 

 ing to the degree that they have impaired the strength of the fiber. 



BLEEDING CREVICES. 



Sometimes in the ash, elm, walnut, oak, 'and other species, there will 

 appear a crevice, often caused at first by some injury, from whic^h the 

 sap will continue to ooze until, perhaps, it may bleed the tree indefi- 

 nitely. Along this slimj', discolored crevice insects find lodgiuent; 

 rottenness appears, and extends, and finally the tree perishes. 



It is recommended by M. des Cars to clean out the crevice with a 

 sharp tool down to the bottom of the diseased part, and apply coal-tar; 

 repeating the process if necessary. In this way a valued tree may often 

 be restored to complete health. Dn flaniel advised the removal of the 

 affected parts down to the live woo<l, and covering the wound with cow- 

 dung mixed with straw; then binding with rags fastened by osier 

 ties. 



