NATURAL ENEMIES OF THE FOREST. 



239 



her is most susceptible to dry rot: the fungus can be spread either by its 

 spawn or by spores, and these latter can be carried even by the clothes or 

 saws of workmen, and are, of course, only too likely to reach sound wood 

 if diseased timber is left about near it; but on the other hand dry timber 

 kept dry is proof against dry rot, and exposure to really dry air is fatal to 

 the fungus. (Boulger, p. 75.) 



About all that can be done to protect the forest against fungi is 

 to keep it clean, that is, to clear out fallen timber and slash, and in 

 some cases to dig trenches around affected trees to prevent spreading 

 or to cut them out and destroy 

 them. Such methods have here- 

 tofore been too expensive to em- 

 ploy in any ordinary American 

 forest, but the time is at hand 

 when such action will prove 

 profitable in many localities. 



For the preservation of cut 

 timber from decay, several 

 methods are used. Fungi need 

 heat, air, moisture and food. 

 If any one of these is lacking 

 the fungus cannot grow. Air 

 and heat are hard to exclude 

 from wood, but moisture and 

 food can be kept from fungi. 

 The removal of moisture is 



called seasoning, and the poisoning of the food of fungi is a process 

 of impregnating wood with certain chemicals. Both these processes 

 are described in Handwork in Wood, Chapter III. 



F\g. 86. Portion of the myce- 

 lium of dry rot or tear fungus, 

 Me rn lilt s lachrymans. This 

 cakelike mass spreads over 

 the surface of the timber. In 

 a moist environment pellucid 

 drops or "tears" distil from 

 it-< lower surface; Hence its 

 name. [Ward: Timber; Fijr 21. J 



ANIMAI, ENEMIES. 



The larger animals working damage to our forests are chiefly ro- 

 dents and grazing animals. Beavers gnaw the bark, while mice and 

 squirrels rob the forest of seed and consequently of new trees. The 

 acorns of white oak are particularly liable to be devoured because of 

 their sweetness, while those of red and black oak, which afford timber 

 of comparatively little value, are allowed to sprout, and thus come 

 to possess the land. Hogs annually consume enormous quantities of 

 "mast," i. e., acorns or other nuts, by pasturing in oak and other 



