vil] 



THE "DRY-ROT^' OF TIMBER. 



177 



deal ; its specific weight diminishes greatly, and that 

 this is due to a loss of substance can be easily proved 

 directly. These changes are accompanied with a 

 cracking and warping of the wood, due to the shorten- 

 ing of the elements as their water evaporates and they 



Fig. 21.— Portion of the mycelium of JMeridiiis lacryntans removed from the sur- 

 face of a beam of wood. This cake-hke mass spreads over the surface of the tim- 

 ber, to which it is intimately attached by hyphse running in the wood-substance. 

 Subsequently it develops the spore-bearing areolae near its edges. The shading 

 indicates differences in colour, as well as irregularities of surface. 



part from one another : if the disease affects one side 

 of a beam or plank, these changes cause a pronounced 

 warping or bending of the timber, and in bad cases it 



N 



