CAUSES OF DECAY AND DESTRUCTION OF TIMBER 257 



statement that any board that is cut and brought into the 

 city from the forest is already covered with these fungi." 



It has been proved that the spores can be propagated by 

 the saw of the workman if after cutting diseased timber he 

 uses the tool on sound wood, and can even be carried on 

 the clothes, and if, as German chemists tell us, four millions 

 of these spores only occupy a cubic millimetre, we can 

 easily judge of the risk of infection. As the human being 

 brings with him from an infected neighbourhood the germs 

 which in time produce typhoid and other diseases, so timber, 

 brought from the forest, brings with it the spores of disease 

 which only require a favourable situation to cause them to 

 propagate and produce decay. These spores distributed by 

 currents of air are what so quickly destroy the timber of 

 dwelling-houses by what is familiarly known as " dry rot," 

 although this is a misnomer, as will be shown ; and it 

 should be the object of all users of timber to bring it into 

 such a condition as to prevent the propagation of fungi and 

 consequent decay. 



The chief " dry rot " fungus is known by the name of 

 Mendius lacrymans, and recent German experiments have 

 proved that it can propagate itself either by mycelia or 

 spores, but principally by the latter. 



Moisture and a certain amount of heat are indispensable 

 conditions for decay of timber. Without moisture no 

 growth of fungus can take place. Temperatures between 

 60 and 100 Fahr. appear most conducive to fungus life, 

 it will not exist at freezing point, and in higher tempera- 

 tures than above given appears to lose its vitality. 



Mr. Eichard Falck, in a recent paper in the Zeitschrift 

 fill- Hygiene, Leipsic, has pointed out that he has been able 

 to prove that warmth is fatal to the growth of dry rot 

 fungus, and that in houses attacked it is possible to destroy 

 it entirely by heating the air to 38 C. (100 Fahr.) for four 



T. S 



