1924 
WOLPERT—FUNGI AND H-ION CONCENTRATION OF MEDIA ) 69 
employed, and that 35? C. is better on the whole than 15° C. 
Pholiota adiposa also grows better in the peptone solution 
than in the Richards’ solution, producing 4-5 times as much 
mat in the first solution as is produced in the second. While the 
fungus grows best at P, 6.0 in the Richards’ medium it does not 
show any such optimum point in the peptone solution. Further- 
more, within the range of these experiments, this fungus does 
not markedly or invariably decrease or increase the active 
acidity of the substratum upon which it grows. 
The mycelial growth of Pleurotus ostreatus (table rx) in the 
Richards’ solution (fig. 11) is limited to a comparatively narrow 
range of Py. At 15? C. growth is inhibited at Рн 3.3 and 7.5, 
but it is evident, however, that the actual limits for growth are 
nearer to Ру 4.0 and 7.0, as at these values only a trace of growth 
is obtained. The optimum Ру range at this temperature is 4.4- 
TABLE IX 
THE GROWTH OF PLEUROTUS OSTREATUS AND THE CHANGES IN THE 
ACTIVE ACIDITY UPON BOTH THE RICHARDS' AND THE PEPTONE 
SOLUTIONS AT DIFFERENT INITIAL Рн AND TEMPERA 
15° C. 25? C. 35° C. 
Рн Wt. of Рн Wt. of Рн Wt. of 
mat in mat in Е mat іп 
Initial | Final mgs. | Initial | Final gs. | Initial | Final | mgs 
3.0 | 3.0 0 
Чч 2 123 0 3.5 | 3.3 28 8.5 | 3.5 0 
| 40 | 3.7 | trace &t| 82 41 0 |347 67 
31 44 | 40 50 Tee 2.8 37 4.5 | 3.6 72 
5.0 | 4.0 41 5.1 | 4.0 70 50 | 4.1 88 
5.5 | 5.5 61 £514 80 83 галасиғ 
S| 6.0 | 61 54 6.0 | 5.3 74 6.0 | 5.2 60 
=| 6.5 | 6.8 57 6.5 | 5.7 49 6.5 | 5.6 73 
70 | 7.0 6.9 | 6.2 44 70 | 5.9 58 
T2742 0 72 | 13 0 72 | 73 0 
JA сс 
351 55 0 ; 
41 3141 46 4-0 6-9 192 42 | 42 0 
RE. 1 48 123 4. 3 
51 50 | 6.4 204 49 | 7.1 136 4.9 | 5.6 35 
e| 5.5 | 6.8 194 5.2 | 6.8 237 52 | 5.8 64 
а 5.7 | 6.8 127 5.7 6.3 255 
=| 6.0 | 7.2 217 5.9 | 6.7 216 6.0 | 6.3 | 207 
9| 6.5 | 7.3 | 195 64 | 6.9 142 65| 72 | 10 
Bl 75 | 77 | 15 | 7.0 | 7.0 | 16 | 7.0 | 79 | 96 
7S | 51 109 7.5 | 8.4 100 7.5 | 8.2 90 
8.0 | 8.0 109 80 | 84 86 80 | 82 91 
8.5 | 8.5 0 8.5 | 8.5 0 8.5 | 8.5 0 
