(Vor. 11 
46 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
and Polystictus versicolor upon a carrot extract-glucose-agar 
medium. His results, expressed in the diametric growth in 
centimeters of the fungus colonies, show that for the first 2 species 
there is little difference in growth from + 5 to + 24.5, 
Fuller’s scale, while at + 2.5 there is a marked retardation. 
Polystictus versicolor, on the other hand, is more sensitive to 
changes in acidity, showing maximum growth at + 9.75 and a 
steady decrease as the acidity increases. He concluded that 
slight variations in the acidity of the substratum did not affect 
the growth of Fomes pinicola and Lenzites sepiaria, while they 
might influence that of Polystictus versicolor. 
Employing Czapek’s, Dunham’s, Reed’s, and Richards’ solu- 
tions, sap from Acer saccharinum, and a pine decoction, a deter- 
mination of the influence of the hydrogen-ion concentration, 
among other things, upon the growth of wood-destroying fungi 
was attempted by Zeller, Schmitz, and Duggar (719). Although 
it is impossible to make any conclusive statements, within the 
range of the experiments the hydrogen-ion concentration was 
not a limiting factor in growth. The control solutions showed 
that in only one series, the Czapek’s solution with K;PO, was 
the reaction definitely alkaline with an initial Рн of 8.6 at the time 
of inoculation. Upon this solution Polystictus versicolor grew 
slowly, changing the reaction to Pa 4.8 within 30 days. Daedalea 
confragosa failed to grow upon this same solution, the final re- 
action being Ри 8.4. These results suggest that all of the wood- 
destroying fungi do not react alike toward slightly alkaline 
solutions. 
Webb (719) studied spore germination of a number of fungi 
in relation to the hydrogen-ion concentration of а M/5 mannite 
medium. Spores of Lenzites sepiaria did not germinate readily 
when the reaction was acid. Increasing acidity from Рн 7.0 to 
3.1-2.8 favorably affected germination of the spores of this and 
of other species of fungi. 
А second paper by Webb (721) showed that increasing acidity 
of mannite, peptone, and Czapek's solutions, sugar beet decoc- 
tion, “water Н.РО, and NaOH," and “water HCl or KOH" 
from neutrality to approximately Ри 3.0 to 4.0 favorably in- 
fluenced spore germination of Lenzites sepiaria and of other 
