1924] 
WOLPERT—FUNGI AND H-ION CONCENTRATION OF MEDIA 85 
In no case is growth secured in the most acid plates, those with 
an initial Рн of 2.8. Lenzites sepiaria does not grow under any 
condition and apparently is unable to utilize the cellulose соп- 
tained in the agar. Polystictus versicolor grows and utilizes the 
cellulose from both poplar and maple woods but not from pine 
and oak woods, while the other 3 species will grow to some extent 
upon celluloses derived from the 4 types of wood. "There is some 
doubt as to the utilization of cellulose from pine and oak woods 
by Schizophyllum commune, for in this, and in a few others, the 
plates remained cloudy in spite of the comparatively active 
growth. Pleurotus ostreatus, one of the most active users of 
cellulose, does not avail itself of the carbon from the pine-wood 
cellulose as readily as of the other forms of cellulose, while 
Polyporus adustus does not show this difference. Most active 
growth and hydrolysis are secured in those plates with an initial 
Ры of 4.6, 5.0, and 6.0. In some cases, however, as with Schizo- 
phyllum commune апа Polystictus versicolor on poplar-wood 
celluloses, growth of the fungi and utilization of the cellulose 
are as marked at Pg 4.0 as in the less acid plates. 
DISCUSSION 
АП of the fungi used in these experiments show growth through 
а considerable range of hydrogen-ion concentration. А brief 
review of the facts, as previously presented, show that the fungi 
studied are partial to acid media, and that in the majority of 
cases they fail to grow in slightly alkaline solutions. It can be 
said for these fungi in general that they are acid-loving organisms, 
but such a statement does not imply that none of them will 
grow upon an alkaline solution. In this respect they exhibit 
some individual differences. 
In the Richards’ solution, the less favorable of the 2 major 
solutions used, there is no indication that any of the 8 species will 
grow in an alkaline culture. Polyporus adustus and Pleurotus 
ostreatus do grow at Pa 7.0. While this tendency to grow in a 
neutral solution is not as marked for Polystictus versicolor as 
for the first 2 species, it does grow better at Рн 7.0 than do the 
other 5. Although in some cases growth is obtained at Pg 6.8 
and 6.9, Daedalea confragosa, Lenzites sepiaria, Schizophyllum 
