THE DESTRUCTION OF WOOD BY FUNGI 369 



blocks have been laid down. The mycelium often grows from 

 a rotten block to the neighbouring sound ones. No fruit-bodies 

 are produced in the streets owing to the traffic. 



6. The wood is rotted by Lentinus lepideus in very much the 

 same manner as by Mcrulius lacrimans (the Dry Rot fungus). E It 



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Fig. 1. 



Mag. 450. Radial-longitudinal section of wood of Pine from a rotten paving-block. A 

 medullary ray is represented crossing four tracheides. The hyphae, j, of Lentinus 

 lepideus are to be seen in the cell lumina. They are sometimes branched, and are 

 provided with clamp connections, c. They make their way from cell to cell through 

 bordered pits, p, or bore holes, h, through the walls. Some hyphce are coated with 

 crystals of calcium oxalate, o. At t the hypha has disappeared and a trail of crystals- 

 has been left behind. Cell contents, ///, still remain in some of the medullary ray cells. 



becomes red and spongy when wet ; it shrinks and cracks con- 

 siderably on drying, and is then very brittle and friable. Cellulose 

 is removed from the cell-walls and hadromal left behind. 



