362 



PHWSIOLOGY OF THE FUNGI 



particular concentration gave abundant germination of A . flavus but had 

 no effect upon ^4. niger. 



Brefeld (1905) was perhaps the first to observe the germination of the 

 spores of various smuts in culture. He noted that the spores germinated 

 poorly or not at all in water, while excellent germination occurred in 

 nutrient solutions (probably dung infusion). Brefeld expressed surprise 

 at the vigorous saprophytic development which followed, especially since 

 the species had previously been known only as obligate parasites. 



More recently it was noted that pretreatment with dung infusion 

 markedly stimulated germination of spores of Ustilago striiformis (Cheo 



Table 59. Percentage of Spore Germination after 15 Hours 

 (Duggar, Botan. Gaz. 31, 1901.) 



Spores of 



Aspergillus niger 



Penicillium glaucum 



Monilia fructigena 



Mucor spinosus 



Phycomyces nitens 



Coprinus jimetarius 



C. comatus 



C. micaceus 



Uromyces caryophyllinus 



Water 





 

 75 

 

 

 

 

 

 100 



Bean 

 decoction 



100 



100 



100 



100 



100 



5-10 







100 



75 



Xutrient-salt 

 solution 



100 



100 



100 



100 



100 















Sucrose 

 solution 



75 

 1 



100 

 1 



2-10 

 

 

 



100 



and Leach, 1950). Untreated spores in distilled water germinated only 

 after 5 to 8 days, and the total germination was less than 1 per cent. 

 Spores soaked in a concentrated horse-dung infusion for 15 days or more, 

 then placed in distilled water, germinated within 5 hr., with a total 

 germination of 50 per cent or higher. The exposure to the dung infusion 

 is believed to increase the permeability of the spore wall, allowing the 

 more rapid absorption of water. It might also be pointed out that the 

 dung infusion evidently contains substances which prevent spore germina- 

 tion until highly diluted or removed entirely. 



Although the spores of the Myxomycetes germinate in distilled water, 

 the percentage may be greater in weak decoctions of the natural sub- 

 strate, such as rooting wood, bark, leaves, or humus (Smart, 1937). 

 Similarly, the conidia of PhyUosticia solitaria germinate more profusely 

 in apple-bark decoction and potato-dextrose broth than in distilled water 

 (Burgert, 1934). While it is possible that increased spore germination 

 is due primarily to some stimulating substance, it seems likely that certain 

 nutrients are also involved. 



The conidia of Glomerella cingulata apparently have special nutritional 

 requirements for germination. There was little or no germination in 



