40 
BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 
L. trabea 50 per cent after 1 year; spores of Trametes serialis 2 per 
cent after 4 years and 3 months ; those of Forties roseus less than 1 
per cent after 18 months ; and those of Lentinus lepideus less than 1 
per cent after 2 years and 7 months. 
All but Fomes roseus have the ability to cast large numbers of 
spores and are shown to be capable of doing so within buildings. 
Lenzites sepiaria cast spores six times in experiments upon the ability 
of the sporophores to survive successive wetting, casting, and drying. 
A fruit body of Trametes serialis in the dark in the fungus pit cast 
spores for 15 days successively. 
Observations upon fruit bodies of Trametes serialis in the bottom 
of a closed fungus pit showed that slight convection currents of air 
carried spores upward and throughout the pit. In mills, air cur- 
rents caused by machinery, humidifiers, and heating pipes are of im- 
portance in disseminating spores cast into the air. Sow bugs were 
observed in this pit beneath the sporophores and were found to bear 
large numbers of the spores upon their bodies and appendages. The 
possible importance of insects and other animals in the dissemination 
of these wood- destroying fungi is suggested. 
A description of the macroscopic and microscopic characters of 
malt-agar cultures of the fungi, with a key for identification, is given. 
The cardinal temperatures for mycelial growth were found to be 
as shown in Table 5. 
Table 5. — Cardinal temperatures for the growth of the mycelium of certain 
wood-destroying fungi. 
Species. 
Cardinal temperatures (° C). 
Minimum. 
Optimum. 
Maximum. 
About 8... 
30 to 34.... 
28 to 30.... 
28 
Above 40. 
Little above 36. 
Trametes serialis 
About 3... 
Below 4... 
About 8... 
Between 32 and 37. 
30 
Above 36. 
28 
Between 36 and 40. 
Secondary spores of certain hymenomycetes have been reported 
by several writers as occurring naturally, and their importance in 
the economy of the fungi has been suggested. Studies were made 
upon the secondary spores of four of the fungi under consideration 
in view of their possible occurrence in a mill environment. Oidia and 
few chlamydospores were found in agar cultures of Lenzites sepiaria, 
and oidia also in wood cultures, and both kinds of spores in agar 
cultures of L. trabea. Chlamydospores were found in agar cultures 
of Trametes serialis and Lentinus lepideus. 
Certain of the physiological relations of the oidia of Lenzites 
sepiaria and L. trabea and the chlamydospores of Trametes serialis 
