40 



BULLETIN 1053, IT. S. DEPARTMENT OF AGRICULTURE. 



L. trabea 50 per cent after 1 year; spores of Trametes serlalis 2 per 

 cent after 4 years and 3 months ; those of Fomes raseus 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. 

 Lenzltes 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 serlalis in the dark in the fungus pit cast 

 spores for 15 days successively. 



Observations upon fruit bodies of Trametes serlalis 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 



toood-destroying fungi. 



Species. 



Cardinal temperatures (° C). 



Minimum. 



Optimum. 



Maximum. 





About 8... 



30 to 34.... 

 28 to 30.... 

 28 











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 serlalis and Lentinus lepideus. 



Certain of the physiological relations of the oidia of Lenzites 

 sepiaria and L. trabea and the chlamydospores of Trametes serlalis 



