1 84 TIMBER AND SOME OF ITS DISEASES. [CHAP. 



that this difficulty in persuading spores to germinate 

 is by no means an isolated instance : we are still 

 ignorant of the conditions necessary for the germina- 

 tion of the spores of many fungi e.g. the spores of 

 the mushroom, according to De Bary ; and it is 

 known that in numerous cases spores need very 

 peculiar treatment before they will germinate. The 

 peculiarity in the case of the spores of Merulius 

 lacrymans was found by Hartig to be the necessity of 

 the presence of an alkali, such as ammonia ; and it is 

 found that in cellars, stables, and other outhouses 

 where ammoniacal or alkaline emanations from the 

 soil or decomposing organic matter can reach the 

 timber, there is a particularly favourable circumstance 

 afforded for the germination of the spores. The other 

 conditions are provided by a warm, still, damp atmo- 

 sphere, such as exists in badly ventilated cellars, and 

 corners, and beneath the flooring of many buildings. 



Careful experiments have shown beyond all 

 question that the " dry-rot fungus " is no exception to 

 other fungi with respect to moisture : thoroughly dry 

 timber, so long as it is kept thoroughly dry, is proof 

 against the disease we are considering. Nay, more, 

 the fungus is peculiarly susceptible to drought, and 

 the mycelial threads and even the young fructifica- 

 tions growing on the surface of a beam of timber in a 



