1 Dec., 1899.] QUEENSLAND AGRICULTURAL JOURNAL. 597 
Durability of Wood.—Wood, under suitable conditions, is very durable, 
but under others it decays rapidly. The constituents of wood are so inert that 
the decay is never brought about by the action of chemical forces alone, but 
always requires the aid of the lower forms of life; the conditions, therefore, 
which favour the decay of wood are always those which favour the growth and 
development of the organisms which produce it. 
Dry Rot.—The best-known disease of wood is that known as dry rot. 
The wood becomes darker in colour, decreases in weight, acquires a musty 
smell, and may become so soft that it can be cut with a knife, “almost like 
cheese” if it be wet, but, if dry, crumbling under very slight pressure to a 
brown powder, and thus the wood becomes weak and thoroughly rotten. Dry 
rot is produced by the growth of a fungus (Merulius lacrymans), which lives 
on the wood and ultimately destroys it. The spores of the fungus germinate 
on damp timber; their germinal filaments pass into the wood, pierce through 
the cell walls and among the cells, so as to draw nutriment from the nitrogenous 
matter, lignine, and other materials present on which they can live, and thus, as 
it uses up part of the material, it disintegrates and breaks up the remainder. 
The conditions which favour the development of the fungus are of two 
kinds—those of the wood itself, and those of the surroundings. The less 
perfectly the wood has been dried, the more readily will the fungus be able to 
find nutriment. Moisture is essential to the development of these forms of 
life, and unless this be present the “ rot?’ cannot set in. ‘Dry timber kept dry 
is proof against dry rot’ (Marshall Ward’s “Timber and Some of its 
Diseases,” page 191). One of the prolific causes of dry rot is the use of wood 
not sufficiently seasoned. Professor Ward says, “ It is clearly an act worthy of 
«madman to use fresh, ‘green’ timber for building purposes; but it seems 
certain that much improperly dried and by no means ‘seasoned’ timber is 
employed in some modern houses. Such wood is peculiarily exposed to the 
attacks of any spores or mycelium that may be near.” : 
As to the surroundings, dampness is one of the most important favourable 
conditions ; and if the wood itself be not damp, it may be in contact with damp 
masonry or other things, and may be surrounded by a damp, stagnant 
atmosphere. ‘These, with darkness and moderate warmth, are just the conditions 
under which the fungus can grow and flourish. 
Obviously, therefore, if dry rot is to be prevented, not only must the 
timber be put in dry, but it must be kept dry, and the space around it must 
be kept thoroughly ventilated. 
Jt must be remembered that the disease is always propagated by the spores 
or mycelium of the fungus. As these spores are extremely small, not more 
than so'¢o of an inch in diameter, and are very light, they will be easily carried 
about, and one piece of timber may infect many others. Dry rot, as far as it 
is known, only attacks wood in buildings, &c., and is unknown in the forest. 
There are, however, many other fungi which produce similar results. Ina 
fine forest, 1b is frequently found that the stumps of the trees which have been 
cut down, whilst little changed in appearance, have become so rotten that they 
can easily be broken up, and often they fall in a powder under pressure. ‘This 
change is due to the action of various fungi, the function of which in nature is, 
no doubt, to break up and destroy useless wood. 
Wet ot.—Growing trees are as subject to decay as cut timber, the heart 
wood being usually attacked, the tree being often left hollow. This is likewise 
usually, if not always, due to the action of a fungus, which, living on the nutritive 
portions of the wood, breaks up and destroys the remainder. 
Other Cases of Decay.— Wood decays more or less rapidly in almost all 
positions, the decay being always the result of the growth of the fungi, or other 
low forms of life, at the expense of the wood, since the constituents of the 
wood are so inert that—apart from the action of living organisms—there would 
be little tendency to decay. 
Preservation of Timber.—Obviously, if the decay of timber is produced by 
the action of living organisms, the decay can be prevented by destroying the 
organisms, or making the conditions such that they cannot thrive. 
