1919] 







WEBB — SPORE GERMINATION AND H ION CONCENTRATION 203 



the author concludes that various fungi exhibit varying degrees of 

 resistance to poisons, and that the limits of resistance may 



the 



;h little data were at hand 



Stevens concluded that the spores of fungi, when compared to 

 the roots of seedlings, were less susceptible to toxic action. 



Duggar ('01) made an extensive study of spore germination, 

 including certain chemical as well as physical stimuli. Using 

 distilled water as the medium, he found that organic acids stim- 

 ulated germination but the percentage of germination was 

 not great. The stimulus of N/100 or less of acetic acid to 

 Aspergillus flavus and Sterigmatocystis nigra was very noticeable. 

 Oxalic acid was more pronouncedly stimulating with Sterig- 

 matocystis, N/100 producing maximum germination, whereas 

 this concentration totally inhibited germination of Aspergillus. 

 In this work, the considerable extent of individual variation was 

 emphasized. 



Ferguson ('02), using an artificial digestive fluid containing 

 solutions of pepsin in distilled water combined with different 

 amounts of HCl also in distilled water, studied the germination 

 of spores of Agaricus campestris, Coprinus comatus, and Cal- 

 vatia cyathiforme, but germination was so erratic that she was 

 unable to draw any definite conclusions. 



Brooks ('06) studied the effect of temperature on the toxic 

 properties of CuS0 4 , HN0 3 , and H 2 S0 4 , as shown by the effect of 

 these substances on the germination and growth of certain fungi. 

 In all the experiments, beet decoction was used as the nutrient 

 medium, the stock infusion containing 600 gms. of beets per 

 1000 cc. of water. At the time of using, the decoction was 

 diluted by the addition of the toxic substance and water to 

 one-half of its former nutritive value. Usually, above the 

 provisional optimum, the deleterious action of the toxic agents 

 increased very rapidly, with rise in temperature. Spores in- 

 hibited by cold were not greatly injured when exposed to harm- 

 ful agents. In all instances, however, the injurious effects were 

 least at the optimum temperature for the fungus; however, the 

 effects of the three chemicals were very different. 



Ayers ('16), making cultures of streptococci in a broth con- 

 taining 1 per cent cerevisine, 1 per cent peptone, 1 per cent test 



3 



