FUNGI OF IMPORTANCE IN THE DECAY OF TIMBERS. 39 
timber, such as inferior southern pine, spruce, and hemlock, which 
have been used in mill construction in recent years, are readily at- 
tacked and destroyed. Hence, the losses through decay by a certain 
group of fungi are large. Because of the practical importance under 
mill conditions of Lenzites sepiaria, L. trabea, Trametes serialis, 
Fomes roseus, and Lentinus lepideus, studies upon the physiological 
relations of the basidiospores, mycelium, and secondary spores were 
undertaken, particular attention being paid to those factors influenc- 
ing intramural dissemination. 
All five of these fungi have been found fruiting more or less com- 
monly upon mill roofs or in basements. Lenzites sepiaria and L. 
trabea do more damage to coniferous roof timbers than has here- 
tofore been reported. 
The basidiospores of the five fungi will germinate upon various 
agars, or wood, in tap water, and irregularly in distilled water. 
At 40° C. the basidiospores of Lenzites sepiaria will germinate in 
large percentages, while those of L. trabea and Fomes roseus give 
small percentages. The spores of the other two fungi will not germi- 
nate at this temperature. The optimum temperatures for rapidity 
of germination are: Lenzites sepiaria, 32° to 35° C. (89° to 97° F.) ; 
L. trabea, 28° to 32 ° C. (82° to 89° F.) ; Trametes serialis, 30° to 32° 
C. (86° to 89° F.) ; Fomes roseus, 28° to 32° C; Lentinus lepideus, 
28° C. Large percentages of the spores will germinate at the lower 
temperatures within the range of growth for each fungus if sufficient 
time is allowed. The percentage of germination is the criterion 
which best shows the effect of temperature upon the viability of the 
spores. 
Diffused light did not affect the germination of the spores. The 
basidiospores of these fungi would not germinate in direct sunlight 
in May, and after two days of exposure few or no spores would germi- 
nate when put in the dark. Two days of direct sunlight in May 
acting upon dry spores usually killed all but a very small percentage, 
if not all of them. The germ tubes showed no phototropic responses. 
In drying tests, basidiospores of Trametes serialis and Lentinus 
lepideus (aged 10 days and 7 months, respectively) were killed in 
about 10 weeks' exposure at 28° and 32° C. (82° and 89° F.) and in 
about a month at 36° C. (97° F.). With fresh spores at 40° C. 
(104° F.), Lenzites sepiaria survived two months and Trametes 
serialis six weeks in an unfinished test. Spores of Fomes roseus five 
months old were killed in one week at the same temperature. 
Alternate wetting and drying is destructive to the spores of these 
fungi. This applies either to the wetting with free water or exposure 
to atmospheric moisture and subsequent drying. 
Basidiospores of Lenzites sepiaria gave a germination of 25 per 
cent after 2 years and 10 months of storage in an ice box ; those of 
