DECAYS AND DISCOLORATIONS IN AIRPLANE WOODS. 39 
A somewhat similar rot in oaks (34) is the honeycomb heart-rot 
(Stereum subpileatum B. and C.). As in the whitish piped rot, the 
first indication of this decay in white oak is a slight water- soaked 
appearance of the fresh heartwood, and when dry this “soak” be- 
comes a tawny color. Next, light- colored isolated areas appear in 
the tawny discolored wood, and pronounced delignification occurs. 
This is indicated by the appearance of very small. irregular whitish 
patches in the light-colored areas. These patches develop into small 
pits with their long axes parallel to the grain of the wood, and they 
increase in number until the affected wood is completely occupied. 
The pits are from one thirty-second to one-fourth of an inch wide 
by one-fourth to five-eighths of an inch long, and lined with cellulose 
fibers. At this stage the appearance of the decay is similar to the 
red-rot in softwoods previously described. Later the cellulose lining 
may disappear. The wood is “probably not weakened by this decay 
until the light-colored areas appear in the tawny discoloration. 
An incipient decay is sometimes encountered in African mahog- 
any, the cause of which is unknown to the writer. This decay ap- 
pears as light-yellow, brown, or merely lighter brown closely crowded 
spots or flecks on the reddish-brown heartwood. These flecks vary 
from one-sixteenth to one-quarter of an inch long and are several 
times longer than broad, the long axis corresponding with the direc- 
tion of the grain in the wood. Such wood is weakened. 
TYPES OF DECAY IN LOGS AND LUMBER. 
In addition to the wood-destroying fungi which normally attack 
living trees, and which may continue to decay the wood after the 
tree is cut, there are fungi which grow only or principally on wood 
in the form of logs or lumber. Owing to their destructiveness, some 
of these deserve more than passing mention. Although it is true 
that damage caused by such fungi is due to improper “handling of 
the timber during the course of manufacture and utilization, unfor- 
tunately such improper handling does occur and must be reckoned 
with. — 
Softwood logs and lumber.—One of the most important of these 
fungi is that which caMses dry-rot in stored logs or lumber and in 
timber in structures (22). The term “ dry- rot” is loosely applied 
to cover almost any type of decay, but it is correctly applicable 
only to the work of the dry-rot fungus (Jlerulius lacrymans ( Wulf.) 
Fr.). This decay is more common on coniferous woods than on 
hardwoods. The incipient decay appears as a yellow-brown dis- 
coloration not easy to detect. Wood with typical decay is yellow to 
brown in color, much shrunken and cracked, and is so badly disin- 
tegrated that it can be easily crushed to a powder. Both sapwood 
and heartwood are attacked. 
_ Another common decay on logs and sawed lumber, particularly 
on railroad ties, is the brown-rot “(62) caused by the brown Lenzites 
(Lenzites sepiaria (Wulf.) Fr.), which is practically confined to 
coniferous wood. The typical decay is brown, friable, and easily 
reducible to a powder. In the early stages of decay infected wood 
is darker in color than the normal. Sometimes the early spring 
wood of the annual rings may be completely decayed, while the 
