16 BULLETIN 1053, U. S. DEPARTMENT OF AGRICULTURE. 



tracted period of moist weather, but efforts with many sporophores 

 at different locations resulted in little success. Sporophores of the 

 annual form of F. roseus were revived to cast a few spores after 20 

 months in the laboratory. 



No data are at hand relative to the length of the spore-casting 

 period of Lentinus lepideus. Sporophores of this fungus will some- 

 times revive in moist atmosphere after having been kept dry a few 

 months (six months at least) and will cast spores. The chief diffi- 

 culty in obtaining prints is that molds growing on the fleshy pilei 

 contaminate them. A single fruit body will liberate a large number 

 of spores in a short time. A large one, about 10 centimeters in 

 diameter, will overnight cover an area half the size of a sheet of 

 paper of letter size with a heavy layer of spores. Attempts to revive 

 sporophores of this fungus 16 and 19 months old were unsuccessful. 



Since these fungi fruit within mills (and at least three of them 

 (Lenzites sepiaria, L. trabea, and Lentinus lepideus) are known to 

 cast spores in abundance under mill conditions) it is probable that 

 basidiospores play an important part in the dissemination of the 

 fungi therein. 



OBSERVATIONS ON THE DISSEMINATION OF THE BASIDIOSPORES OF TRAMETES 



SERIALIS. 



The works of Falck (14) and Buller (8) have given us some infor- 

 mation on the dissemination of the basidiospores of hymenomycetous 

 fungi. Falck showed how the spores were dispersed uniformly 

 within closed glass vessels, even to some height within narrow con- 

 tainers. His method of determining the dissemination was by col- 

 lecting spore deposits upon shelves or ledges at various locations 

 throughout the chamber. He showed with what ease currents of air, 

 invisible and imperceptible, caused by temperature changes could 

 transport the basidiospores. He found that insulated fruit bodies 

 in insulated glass chambers have a higher temperature than the 

 surrounding atmosphere and formulated a theory that the ability 

 to produce this higher temperature was an adaptation serving to 

 warm the layers of air beneath the pilei for the purpose of producing 

 convection currents to disseminate the spores. He Avent farther and 

 maintained that the thickened pilei of fleshy hymenomycetes were 

 symbiotic adaptations providing food for maggots, whose respiration 

 produces heat. Buller (8) demonstrated basidiospore dissemination 

 by means of his beam-of-light method. His work was more com- 

 prehensive than Falck's, and while agreeing with Falck's general 

 conclusions as to the ease of dissemination of these spores, he could 

 not regard it as demonstrated that the heat of the pileus was of 

 material help in disseminating spores in the open. He maintained 

 that the convection currents naturally present at all times out of 



