158 EFFECTS OF REACTION OF SUBSTRATE ON FUNGI 



As is well-known, temperature modifies the rate of growth, but 

 it is also an important factor in modifying the pH range. Tem- 

 peratures favorable for optimal development tend to be corre- 

 lated with the widest pH range. Wolpert (1924) grew each of 

 the species listed in Table 13 at 15° C, 25° C, and 35° C, all other 

 factors being identical. Lenzites saepiaria, Pleurotits ostreatus, 

 and Arnnllaria mellea have high optimal temperatures, Schizo- 

 phyllum commune has a low one, and the remainder have inter- 

 mediate optimal temperature requirements. 



The comparative growth of Ophiobohts graminis on Czapek's 

 nutrient fortified with cane sugar and on corn-meal decoction led 

 Webb and Fellows (1936) to conclude that the nutritional and 

 physical nature of the media, irrespective of all other factors, 

 greatly modifies the influence exerted by free hydrogen or hy- 

 droxvl ions on the growth of fungi. 



pH of fungus tissues. Essentially nothing is known about the 

 hydrogen-ion concentration of fungus tissues. Armstrong (1929) 

 measured the reaction of the juice of crushed stipes and pilei of 

 certain fleshy fungi, with the results shown in Table 14. 



TABLE 14 

 Hydrogen-Ion Concentration of Fungus Tissues 



