82 
Mycologia 
other species of timber. Wood classed as heartwood was always 
selected well within the sapwood ring. 
The present paper comprises tests on 28 species of conifers and 
presents data only on single specimens of wood for three different 
test periods. As it consists in but one set of tests the figures should 
be considered as preliminary and indicative rather than final. 
Other tests now under way will throw further light on the ques- 
tion and when sufficient data have accumulated generalizations 
will become admissable. Due consideration to these facts should 
be given in interpreting durability values. Also, the fact that dif- 
ferent samples of the same kind of wood show different durabil- 
ities, depending upon their physical, and possibly chemical, consti- 
tution must be kept in mind in establishing a true conception of 
the resistance which the woods offer to decay. 
The very destructive and vigorous-growing fungus, Lentinas 
lepideus Fr., which is abundantly distributed on coniferous timber 
over practically the entire United States, was selected for this 
first series of tests on account of its very rapid growth and the 
vigor with which it is known to rot many species of conifers in 
nature. The culture was secured from a tissue transfer taken 
from a plant collected by the writer from a Douglas fir stump in 
Montana in 1910. The purity of the culture is unquestioned; it 
has produced typical, but, of course, reduced, fruit-bodies several 
times during the course of the tests {Plate 18^.) 
Method 
All tests have been conducted in 2-liter Erlenmeyer flasks, 
plugged rather tightly with absorbent cotton, and then capped with 
thin muslin soaked in a dilute solution of mercuric chloride. 
The flasks were prepared in triplicate, the original intention 
being to examine the first at the end of three months, the second 
after six months, and the third after nine months. Field work 
interrupted this schedule somewhat, as noted by the tables. 
The test woods were identified and the logs marked with a 
stencil or paint in the forest by the various collectors. They were 
then shipped to the laboratory in a green condition and sawn as 
needed. The blocks for durability tests were cut ^ by ^ inch 
