vii.] THE "DRY-ROT" OF TIMBER. 179 



ning between and in the wood elements, and also on 

 the surface, and there forming cake-like masses (Fig. 

 21). In a vast number of cases, longer or shorter, 

 broader or narrower, cords of greyish-white mycelium 

 may be seen coursing on the surface and in the cracks : 

 in course of time there will be observed flat cake-like 

 masses of this mycelium, the hyphae being woven into 

 felt-like sheets, and these may be extending themselves 

 on to neighbouring pieces of timber, or even on the 

 brick-work or ground on which the timber is resting. 

 These cord-like strands and cake-like masses of felt, 

 with their innumerable fine filamentous continuations 

 in the wood, constitute the vegetative body or mycelium 

 of a fungus known as Merulius lacrymans. Under 

 certain circumstances, often realized in cellars and 

 houses, the cakes of mycelium are observed to develop 

 the fructification of the fungus illustrated in Fig. 22. 

 To understand the structure of this fructification we 

 may contrast it with that of the Polyporus or Trametes 

 referred to in Chapters V. and VI. ; where in the latter 

 we find a number of pores leading each into a tubular 

 cavity lined with the cells which produce the spores, 

 the Merulius shows a number of shallow depressions 

 lined by the spore-forming cells. The ridges which 

 separate these depressed areolae have a more or less 

 zigzag course, running together, and sometimes the 



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