AMERICAN 
JOURNAL OF BOTANY 
Vol. X October, 1923 No. 8 
THE EFFECT OF HEAT UPON THE MYCELIUM OF CERTAIN 
STRUCTURAL-TIMBER-DESTROYING FUNGI 
WITHIN WOOD 1 
Walter H. Snell 
(Received for publication November 28, 1922) 
The possible use of heat for checking decay in buildings has been 
suggested by various European writers, but little has been done either in an 
experimental or in a practical way to test its efficacy. Falck (1, p. 197; 
2, pp. 338-340) made some tests upon the effect of heat upon the mycelium 
of some wood-destroying fungi in agar and in wood. The tests were not 
run in a systematic series, and Falck’s only conclusion was that, whereas 
heat may be applicable for the checking of Merulius lacrymans within 
structures, it is not feasible in the case of Lenzites sepiaria, for heat is 
necessary for long periods and at high temperatures to kill this fungus. 
Hoxie (3, pp. 38-40) reports an experiment carried out in a mill infected 
with Merulius lacrymans and Coniophora cerebella, in which encouraging 
results were obtained by heating the building by means of its own heating 
system four times from Saturday noon to Monday morning to about 
115 0 F. (46° C.). 
The present paper gives the results of a series of tests upon the resistance 
to heat of the mycelium of certain wood-destroying fungi within wood and a 
discussion of the application of these results to the heat treatment of decayed 
timber in buildings, and to the kiln-drying and preservation of wood. The 
fungi are five found to be of importance in the decay of mill timbers, viz., 
Lenzites sepiaria , L. trabea, Trametes serialis , T. carnea, and Lentinus 
lepideus (6). 
Methods 
The cultures of the five fungi were made in 2-liter Erlenmeyer flasks in 
the manner described by Humphrey (5), using Sitka-spruce blocks f by J by 
2 inches. Tests were made upon blocks from cultures incubated 4 months 
and from cultures incubated I year. In one case the blocks were thoroughly 
1 This work was suggested to the writer by Dr. C. J. Humphrey, begun at the Labora¬ 
tory of Forest Pathology, Bureau of Plant Industry, Madison, Wis., and finished in the 
Botanical Laboratory at Brown University. 
[The Journal for July (10: 343-378) was issued July 28, 1923.] 
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