™, ¢ 5 
88 FORTY-FIRST ANNUAL REPoRT ON THE 
dried or seasoned before use, the decay commenced is checked and 
will not revive until the wood again becomes moist from external 
causes. On the contrary, if such wood is put into structures while 
damp and unseasoned, then painted or confined where the moisture is 
retained, the decay will continue, the rapidity depending upon the 
continued amount of damp and warm weather or equivalent con- 
ditions. This is commonly and erroneously called “dry rot.” Decay 
of dry wood can not take place without moisture. 
It is well established by numerous proofs that seasoned woods last 
in all conditions of service where it is unfavorable for the growth 
of fungi, and decay in all conditions where they can grow, uniess the 
timber is judiciously treated. The propayation of fungi upon timber 
may be either by germination of spores, which are thrown off by 
thousands when in fructification and disseminated by the air, or by 
revival of mycelium already on or in the wood. 
Besides the ever-present spores of a fungus or its mycelium in 
timber, three essential conditions in combination are necessary for the 
decay of wood, or in other words, the growth of a fungus. 
First. Moisture, either external or internal. 
Second. A temperature between 40° and 120° Fahr., 75° to 90° 
being the most favorable for the maximum growth of fungi. 
Third. A small amount of air, still or nearly quiet. Free circula- 
tion or winds check the growth of mycelium when in direct contact 
with it. 
When wood must be exposed to these three conditions, sooner or 
later, according to its structure and cell contents, fungi grow and 
destroy it as a result of a natural law of their growth. Therefore, to_ 
protect seasoned wood from decay, the combination mentioned must 
be prevented from taking place by rejecting either one of the three 
elements; or, if that is impossible, an antiseptic or preservative must 
be used to prevent the growth of any fungi. This brief statement 
comprehends, both theoretically and practically, what is necessary to 
be done to preserve timber structures from decay, but to reduce the 
principles to practice, so as to meet all conditions of service which 
may occur, requires a knowledge of the structure of the particular 
wood, its cell contents, size of stick to be used and care in seasoning. 
Also a knowledge of the special fungus or fungi attacking the species 
of wood, and the value and proper use of preservatives and 
antiseptics. : 
Species of fungi which I have found upon specific woods when used as 
railroad ties or in bridges. 
The fungi peculiar to white oak, Quercus alba, Lu, are Polyporus 
a 
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