Jan. 14, 1918 Cultures of Wood-Rotting Fungi on Artificial Media 65 



Lentinus lepideus. Since the rot was sent in as a specimen of heartrot 

 found in the western yellow pine in Oregon, the writers are wondering 

 whether L. lepideus produces a real heartrot of living pine in that State 

 or whether this rot came from a dead area on a living or from a dead tree 

 which had been attacked by this saprophytic fungus. 



Many other instances could be cited of the determination of the causa- 

 tive organism of a rot by use of the cultural methods here outlined. 

 Usually it is not even necessary that the sporophore stage should be 

 developed, since the vegative cultural characters on the 10 special media 

 will usually determine the identity of the fungus. The practical impor- 

 tance of such a method of determination is of great value and is easily 

 recognized by anyone who has worked for any length of time with organ- 

 isms of this character. In fact, one of the worst stumbling blocks to a 

 successful study of the various rots of wood, both saprophytic and 

 heart rots, has been the lack of methods by which the organisms producing 

 these rots could be grown and identified in pure cultures on artificial 



media. 



SPOROPHORE PRODUCTION 



The fact has long been known that the production of sporophores in 

 nature in many of the Hymenomycetes was more or less dependent 

 upon light. This fact has also been demonstrated for a few species mainly 

 by gross cultures on dung decoctions, pieces of wood, bread, etc. 

 Buller {4) has shown among other things how the light influences sporo- 

 phore production for a few species, mainly Agaricaceae, but none of his 

 experiments were made with pure cultures on artificial media. It has 

 been taken for granted that light was essential to the formation of 

 sporophores of the wood-rotting fungi, including the Polyporaceae, but 

 such had never been proved with pure cultures under control conditions on 

 artificial media with a sufficiently large number of species to determine 

 the actual influence of light as well as other factors on sporophore pro- 

 duction. 



The studies here made indicate that there are many Polyporaceae 

 which fruit in diffused light of varying degrees of intensity and others 

 apparently require the direct rays of the sun to produce perfect spore- 

 bearing sporophores, while some can form sporophores in absolute 

 darkness. Since this is only a preliminary report, no attempt is made to 

 determine a large number of factors which should be ascertained in a 

 complete study of this phase of fungus life. For instance, there must 

 be a minimum, optimum, and maximum condition as to light, heat, and 

 moisture under which a given fungus will produce sporophores. 



It will be seen by consulting Table XVI that only three species, 

 Polyporus farlowii, Trametes serialis, and P. cinnabarinus , were able to 

 develop sporophores in absolute darkness. Only the first two of these 

 fungi produced both sporophores and spores. P. cinnabarinus pro- 

 duced fairly typical pores, but no spores were found. 

 27805°— 18 3 



