36 BULLETIN 1128, U. S. DEPARTMENT OF AGRICULTURE. 
darker colored bands of heartwood which are found in some trees, 
but such bands are confined to a definite group of annual rings. 
Redwood is subject to a brown friable decay which is not con- 
fined to the butt of the tree. The fungus causing this is unknown 
(57). The first indication of the incipient decay is a very faint 
light brownish discoloration on the light-cherry to deep reddish 
brown heartwood. This is most readily detected on the tangential 
face in the summer wood. When the brownish discoloration is 
plainly apparent, the decay has progressed so far that the affected 
wood feels softer than the normal to the thumb-nail. The typical 
decay is dark brown in color, very soft, and easily crumbled. Thin 
crustlike mycelium felts occur along the sides of the cracks. 
These reddish brown or brown friable decays which are so difficult 
to detect in their incipient stages, particularly in woods with a pro- 
nounced reddish or brownish heartwood, reduce the strength of ‘the 
wood far more seriously than incipient decays of the red-rot type; 
in fact, the wood may be weakened before the incipient decay is 
visible. Consequently, in cutting out such decays from lumber it is 
advisable to leave a margin of safety of at least 2 feet in a longi- 
tudinal direction beyond the last visible evidence of the incipient 
stage. 
Incense cedar is very commonly decayed by the incense-cedar dry- 
rot fungus (Polyporus amarus Hedge.). The typical decay con- 
sists of vertically elongated pockets, varying in length from half 
an inch to about a foot, which are filled with a brown friable mass, 
and the line of demarcation between the sound and decayed wood is 
very sharp. In some of these pockets small cobweblike or feltlike 
masses of white mycelium occur. The pockets are separated from 
each other by what appears to be sound wood, although in some 
eases streaks of straw-colored or brownish wood may extend verti- 
cally between two pockets. This is especially noticeable between 
young pockets. The pockets of incipient decay are at first firm 
and very faintly yellowish brown. This color deepens slightly, and 
the wood becomes somewhat soft. The incipient decay extends but 
a short distance vertically in advance of the typical decay, and a 
_ distance of 2 feet beyond the last visible evidence will usually exclude 
all decay. The incipient decay is only faintly apparent, occurring 
as it does in pockets with the color in the very earliest stages differ- 
ing but slightly, when at all, from the normal wood. The fact that 
an occasional pocket may be found several feet in advance of the 
main body of decay makes this decay an exceedingly dangerous one. 
The wood, even in an incipient pocket is decidely weakened (al- 
though the intervening wood is apparently not affected), and this 
makes a weak spot that is hard to detect. Such cases are fortunately 
not common, and the fact that most incense-cedar stands are so badly 
decayed will probably preclude this species from any extensive use 
for airplane construction. Other woods are subject to similar decays. 
That found occasionally in western red cedar may be caused by the — 
same fungus, while “peckiness” of bald cypress (Laxodium dis- — 
tichum (linn.) Rich.) results (33) from the work of a different 
organism (omes geotropus Cke.). . 
One of the most striking discolorations indicating decay and at _ 
the same time one of the most serious incipient decays is that caused 
