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WOLPERT—FUNGI AND H-ION CONCENTRATION OF MEDIA 05 
(8) With the exception of a slight decrease of the initial acidity 
by Polyporus adustus in the more acid solutions, the mycelial 
growth of all of these fungi increases the acidity of the Richards' 
solution. 
(9) The active acidity of the peptone-nutrient solution is always 
increased by Lenzites sepiaria and decreased by Pleurotus ostreatus. 
The other 6 species tend, with some minor exceptions, to decrease 
the acidity in solutions where the initial Ру is more acid than 
6.0 and to increase the acidity in solutions where the initial Pg 
is less acid than 6.0. 
(10) АП the species grow in а medium with peptone as the 
only source of both nitrogen and carbon. Неге growth is as 
good or even better than in the Richards' solution where carbon 
is supplied in the form of cane sugar and nitrogen as NH,NO.;. 
(11) These species are capable of utilizing filter-paper strips 
as a source of carbon in а 0.5 per cent peptone solution: Poly- 
stictus versicolor, Armillaria mellea, and Pleurotus ostreatus 
utilize the cellulose most actively, while Lenzites sepiaria and 
Schizophyllum commune utilize it the least. 
(12) Lenzites sepiaria, Polystictus versicolor, Pleurotus ostreatus, 
Polyporus adustus, and Schizophyllum commune make some use of 
white oak-, pine-, and maple-wood celluloses, when these are sub- 
stituted for sugar in the Richards’ solution. Pleurotus ostreatus 
and Polyporus adustus grow best, and Lenzites sepiaria the least, 
of the 5 species used. While Lenzites sepiaria is unable to use 
cellulose from poplar wood, the other 5 species do use it. 
(13) Polystictus versicolor, Pleurotus ostreatus, Polyporus adus- 
tus, and Schizophyllum commune use these same celluloses in the 
Richards’ solution solidified with 2 per cent agar, while Lenzites 
sepiaria fails to grow under these conditions. 
(14) None of the species grow as well in a solution where 
cellulose is the source of carbon as where sugar and peptone are 
the sources. | 
(15) Of the 3 types of liquid media, the peptone-nutrient 
solution with sugar is by far the best. These fungi appear to make 
tter use of organic forms of nitrogen than they do of the inor- 
ganic forms. 
(16) It is the belief of the author that under environmental and 
