\ : I ‘ 
90 Forry-rirst ANNUAL o Rppone ON THB sae “i ty 
y ‘ + hh 4 
some degree from the decay which takes place around the spikes and 
under the rails, from the fact that the iron in contact with this— / g 
wood neutralizes its natural antiseptic. The ends and centers of 
chestnut ties are sound after the rails have cut into the wood enough 
to necessitate their removal. The opinion is quite prevalent that they 
do not decay, but are mostly destroyed by mechanical abrasion; which 
is not the fact, for the microscope reveals the truth, the presence of 
the mycelium of a fungus and its destructive work on the wood fibers 
as an important reason of their rapid abrasion. : 
The chestnut is lighter than the white oak and many of the wood 
fibers much coarser, which enables it to be impregnated with an anti+ 
septic quite readily. The large ducts of the two woods are about 
the same size. The medullary rays of the chestnut are fewer than 
of the white oak, and it is, therefore, more easily indented as a tie. 
The fungus which principally attacks the white cedar, Chamecyparis 
spheroidea, Spach., is Agaricus campanella, Batsch. It even attacks the 
growing tree, and in most cases its mycelium is found in the ties 
when cut. The tree isa very slow grower and, as the lower limbs 
.become shaded, they die and are attacked by their special fungus, and 
this communicates with the upright cells of the tree. It takes’ from 
ten to twenty years before the limbs break off and the wound or orifice 
is closed by the growing wood. As long as air has access to the 
mycelium it slowly grows and destroys the wood above and below the - 
wound, the decay spreading laterally very slowly, owing to the small) — 
medullary rays and the preservatives they contain. As soon as the © 
orifice is closed, shutting off the air supply, the decay for the time 
is nearly if not entirely checked. When the trees are cut for ties it 
is not uncommon to find one or more decayed spots, from one-half to 
an inch in diameter, extending nearly the entire length of the tie. ‘i 
The durability of the wood is so great that such ties are not 
rejected as long as there is suflicient sound wood for spiking. This 
wood contains a natural preservative and is very durable in contact — 
with the soil, but its structure is too h¢ght and delicate to long with- 
re 
stand the heavy traffic of trunk lines, though from its durability itis 
valuable for those of moderate traffic. Ms 
The fungi which destroy ties made of Tamarack, Lari ‘ania 3 
Mx., are Polyporus pinicola, Fr. and Trametes Pini, Vr. 
The fruit of the former always shows traces of phosphoric acid. 
This wood is heavier than white cedar, the wood cells being larger, ta 
with thicker walls. It is also much stronger because the cells in the — 
annual layer formed in the autumn are nearly solid and in sufficient 
number to resist indentation or cutting of the ties by the rails under ‘i 
