8o Journal of Agricultural Research voi. xii, no. 2 



INFLUENCE OF INOCUI.UM ON SPOROPHORE DEVELOPMENT 



In a few of the species of fungi the interesting fact developed that 

 when tissue from sporophores was used for the inocula the presence of 

 this tissue materially shortened the development period for sporophores 

 on the agar. For instance, in Polyporus alhidus from Pinus ponderosa 

 (FP 21875), when tissue was used as an inoculum on corn-meal agar, 

 the development period of the sporophore was 5 days; when mycelium 

 from potato agar was used the development period was 1 1 days ; for 

 P. anceps from Thuja plicata (FP 21 801), when tissue was used on malt 

 the development period for the sporophore was 5 days; when mycelium 

 from potato agar was used for the inoculum on malt agar the development 

 period was 12 days. This rapid formation of the sporophore when tissue 

 was used as an inoculum was characteristic of many of the strains of 

 this group of fungi. 



This shortening of the development period of the sporophores is also 

 found occasionally in other species of fungi than this group. For instance, 

 it was rather marked in Polyporus dryophilus when fresh sporophore 

 tissue was used, in various strains of Trametes peckii, and to a slight 

 extent in Fomes roseus. In several cases not only was the development 

 period for sporophores shortened by the presence of pieces of sporophore 

 used as the inoculum, but cultures made from infected wood, mycelium 

 or spores produced sporophores only on one or two agars, while the same 

 species would produce sporophores on several media when the inocula 

 were pieces of sporophores. In those cases where the sporophore tissue 

 shortened the development period, the pores usually but not always 

 start directly on the tissue inoculum and then spread rapidly often over 

 the entire agar slant. In no case was the development of the pores 

 limited to the pieces of inoculum, while in many instances the pores 

 would start on areas not immediately adjacent to the inoculum. 



SUMMARY 



(i) The following criteria were found of value in the differentiation of 

 the various species: (a) Macroscopic characters, including rapidity of 

 growth, color of aerial and submerged mycelium, character of the aerial 

 mycelium as to texture, etc., staining of the agar, decoloration of the 

 agar, the comparative rate of growth between the aerial and submerged 

 mycelium, etc. (b) Microscopic characters, such as septation, branching, 

 size and color of hyphge, clamp connections, polymorphism in spore for- 

 mation,' etc. 



(2) The sunlight was found to accentuate the colors and tone down the 

 mycelial growth of the fungus, thereby making it more characteristic and 

 uniform for a given species than when placed under similar conditions in 

 the darkness or in weak diffused light. 



(3) The cultural characters of vegetative development of the various 

 strains of a given species of fungus show no appreciable difference between 

 cultures of this fungus whether obtained from infected wood or from 



