SPORE GERMINATION 



367 



species of Amanita was considerably improved by the presence of the 

 yeast. None of the seven species of Boletus germinated on malt agar 

 without the yeast. On the same medium and in the presence of Torulopsis 

 sanguinca, germination was obtained with spores of B. bovinus, B. elegans, 

 B. flavidus, B. granulatus, B. luteus, B. variegatus, and B. viscidus. Some 

 germination of Boletus spores was also obtained in the presence of living 

 colonies of certain other fungi, but none was so effective as Torulopsis. 

 Spores of certain other fungi {Hijdnum repandum, H. imhricatum, Craterel- 

 lus lutescens, Lycoperdon umhrinum, L. echinatum., L. nigrescens, L. pra- 

 tense, L. pyriforme, and Scleroderma aurantium) germinated in Fries's 



Table 62. Germination of Single Myxomycete Spores 

 (Smart, Aryi. Jour. Botany 24, 1937.) 



experiments only in the presence of T. sanguinea. He also tested the 

 effects of mycelial extracts on spore germination and found that extracts 

 of certain species of Boletus stimulated germination of spores of the same 

 species. Many of the fungi studied by Fries are believed to be mycorhizal 

 and may require the presence of a special set of conditions, perhaps the 

 roots of certain plants (or conditions which simulate their presence), 

 before germination will occur. 



The time required for a spore to germinate after being subjected to 

 favorable conditions is a reflection of the interaction and relative impor- 

 tance of all the various influencing factors. The nearer all these factors 

 are to the optimum, the shorter will be the time required for germination. 

 Time is an important factor for the subsequent infection of the host. In 

 nature the near-optimum environmental conditions, principally tempera- 

 ture and moisture, may persist for bvit a short time, and a change in but 

 one of these factors may inhibit spore germination. 



