vii.] THE "DRY-ROT" OF TIMBER. 181 



are produced in enormous numbers (Fig. 23, A) on this 

 areolated surface, which is directed downwards, and 

 is usually golden-brown, but may be dull in colour, 

 and presents the remarkable phenomenon of exuding 

 drops of clear water, like tears, whence the name 

 lacrymans. In well-grown specimens, such as may 

 sometimes be observed on the roof of a cellar, these 

 crystal-like tears hang from the areolated surface like 

 pendants, and give an extraordinarily beautiful ap- 

 pearance to the whole ; the substance of the glistening 

 Merulius may then be like shot-velvet gleaming with 

 bright tints of yellow, orange, and even purple. 



It has now been demonstrated by actual experiment 

 that the spores of the fungus, Merulius lacrymans, will 

 germinate on the surface of damp timber, and send 

 their germinal filaments into the tracheides, boring 

 through the cell-walls (Fig. 23, D), and extending 

 rapidly in all directions. The fungus mycelium, as 

 it gains in strength by feeding upon the substance of 

 these cell-walls, destroys the wood by a process very 

 similar to that already described (compare Fig. 14). 



It appears, however, from the investigations of 

 Poleck and Hartig, that certain conditions are 

 absolutely necessary for the development of the 

 mycelium and its spread in the timber, and there can 

 be no question that the intelligent application of the 



