34 
BULLETIN 510, U. S. DEPARTMENT OF AGRICULTURE. 
Of the fungi having a smooth under surface, two species are 
common enemies of structural timber — Stereum fasciatum Schw. 
(PL VIII, figs. 3 and 4) and S. lobatum Knze. These fungi are 
too much alike for the layman to attempt to distinguish between 
them. They are very thin and flexible, the individual shelves often 
growing one above the other. The general color is grayish to creamy. 
Among the incrusting forms three deserve particular attention, 
viz, Merulius lachrymans (Wulf.) Fr., Coniophora puteana (Schum.) 
Fr. ( = C. cerebella (Pers.) Schrot.), and Peniophora gigantea (Fr.) 
Mass. The first two species are notoriously dangerous and have been 
found in a number of lum- 
beryards extending from 
Massachusetts to the Gulf 
of Mexico. They are also 
the most frequently re- 
ported of all fungi occur- 
ring in buildings, and also 
the most destructive. 
M erulius lachrymans 
(PI. II, figs. 1, 2, and 6, 
and PL IX, figs. 1 and 2) 
is a soft, subgelatinous 
fungus, forming a brown, 
crumpled growth with a 
white, fluffy margin over 
the surface of timber. As 
it develops it produces 
dirty gray to brownish 
minutely porous strands, 
which serve for the con- 
duction of water, thus en- 
abling the fungus to 
spread rapidly over com- 
paratively dry substrata. 
For this reason it has been frequently termed the " dry-rot fungus." 
On account of its destructiveness to buildings in Europe it also goes 
under the German name " Hausschwamm." It rots coniferous timber 
for the most part. 
Coniophora puteana (PL VIII, figs. 5 and 6) resembles Merulius 
lachrymans in color and general habit of growth. It is less gelati- 
nous, however, and produces no porous strands. In some situations 
it produces a smooth, very thin, membranaceous layer on the surface 
of timber; at other times the surface is quite warted or convolute. 
The danger from the fungus is enhanced by its ability to rot hard- 
wood as well as coniferous timber. 
Fig. §5. — Projecting ends of lumber which have de- 
cayed by coming in contact with the ground. 
