1924) 
WOLPERT—FUNGI AND H-ION CONCENTRATION OF MEDIA 87 
TABLE XVI 
THE HYDROGEN-ION CONCENTRATION, EXPRESSED IN Рн, 
APABLE OF INHIBITING MYCELIAL GROWTH 
Solution 
Richards' Peptone 
fune Acid limit Alk. limit Acid limit Alk. limit 
er in Рн in Ри in Рн in Рн 
"0. ©, 422 yi BS 
15 | 25 [85-115 41295-1 35 1 15 |251 85 | 15 | 25 | 35 
S. commune 3.7|3.4|3.4|7.1/6.9|7.0/|3.5|2.8|2.9|8.5|[8.51|8.5 
L. sepiaria 3.5|3.5|3.5|7.3|7.1/6.9|2.8|2.8|3.0|7.4|7.517.6 
Ph. adi 8.4|2.81|3.416,9|7.01|6.9|3.0|2.812.81|7.5|7.61|7.6 
P. versieolor 8.5|2.513.0|7.8|7.616.8|2.512.518.017.417,5|7,5 
РІ. ostreatus 8.3|2.913.5|7.5|7.2|7.5|3.5|3.0|4.2/|8.5|8.518.5 
D. confragosa 4.0|3.5|3.5|5.5|7.2|7.2|3.3|2.8|2.8|7.6|7.5|7.5 
P. adust 8.5|3.81|3.3|7.5|7.5|7.6|92.0|2.012.818.018.0|8.0 
А. mellea 3.412.9 13.5 '7.4 6.9 6. 9 2.512.012.5 [7.5 17.8 Ж. 
checked, or else is very poor, in alkaline solutions, and is inhibited 
in the acid range Pg 3.0-3.5 in the Richards’ solution and 2.5-3.0 
in the peptone solution. Schizophyllum commune and Pleurotus 
ostreatus are more tolerant to alkaline media and less tolerant to 
acid media, and Polyporus adustus is more tolerant to both alkali- 
nity and acidity than are the above 5 species of fungi. These 
conclusions agree with those reached by Rumbold (’08), Spauld- 
ing (211), Zeller (716), and others who have observed that Len- 
ziles sepiaria is extremely sensitive to traces of alkalinity. Zeller, 
Schmitz, and Duggar (719) reported that Polystictus versicolor 
grew at Ри 8.6 in a Czapek's solution, changing the initial acidity 
to Pa 4.8. It is evident that fungi respond to wider or narrower 
ranges of Ри in response to various complex factors. Such a 
complex and interdependent set of environmental and physiolo- 
gical conditions control the vitality of these fungi that it is diffi- 
cult to foresee just why divergent results are obtained at different 
times. 
Without an exception the widest optimum Ру range is obtained 
in the more favorable medium, the peptone solution. Here, 
with individual variations, the optimum growth-zone is between 
Pa 3.5 and 6.5. In the less favorable solution, the Richards’ 
Solution, the range is more limited, being Ри 4.0-6.0. This does 
not imply that the optimum range always falls entirely within 
these limits or that growth is always equally good throughout, but 
