232 



WOOD AN"D FOREST. 



than in the east, — in tlie Enckies, for instance, where there are elec- 

 trical storms without rain. 



Fires will be considered later under man's relation to the forest. 



Stiow and ice often tiring serious harm to saplings by perma- 

 nently bending them over, Fig. 78, or by breaking oif tops and 

 branches. 



Frost kills young jtlants; and sudden changes in temperature 

 seriously affect grown timber, producing "frost checks" and "wind 



Fit'. 7». Slim Trees Kent Over by Siiuw; Stouter Trees Uiiliarmed. Zuricb, 

 Sn-iizerland. /_'. S. Furfsl S\-/ zicc. 



shakes." When tliere is a sudden fall in temperature, the outside 

 laj-ers of the ti-ee, «liieh are full of sap, contract more rapidlv than 

 the inner portions, with the residt tliat tlie tree splits with a sudden 

 pistol-like rcpoi't, the check luiniiug radially up and down the tree. 

 This is called a "frost check" or "star shake," Fig. -il.a, p. 47, and 

 such woimds I'arely heal, Fig. T!*. 



On the oiliei- liand wlien the temperature rapidly rises, the outside 

 layers of the tree cxjiand so much more rapidly than the inside, that 

 they separate with a dull mnllled chug, t}ie cheek extending in a cir- 



