] 
WOLPERT—FUNGI AND H-ION CONCENTRATION OF MEDIA 73 
TABLE X 
THE GROWTH OF POLYSTICTUS VERSICOLOR AND THE CHANGES IN THE 
ACTIVE ACIDITY UPON BOTH THE RICHARDS’ AND THE PEPTONE 
SOLUTIONS AT DIFFERENT INITIAL Рн AND TEMPERATURES 
15? C. 25? C. 35? C. 
Рн Wt. of Рн Wt. of Ри Wt. of 
mat in mat in mat in 
Initial | Final mgs. | Initial | Final mgs. | Initial | Final | mgs. 
2.5 | 2.5 0 
2.9 | 2.9 20 2.9 | 2.9 0 
SI 85 0 25 34 30 3.5 | 3.3 | trace 
E $28 | 37 43 $8 | 5.5 48 8.8 | 3.6 60 
«4| 4.2 | 3.6 51 4.2 | 3.4 71 42 | 3.8 72 
$| 5.0 | 4.6 59 5.0 | 3.6 70 50 | 42 51 
8| 55 | 5.2 55 5.5 | 5.0 86 5.5 | 52 88 
*| 60 | 59 44 6.0 | 5.5 65 6.0 | 5.5 57 
&l 6.5 | 6.2 47 6.5 | 57 47 6.3 | 5.5 54 
6.7 | 6.7 32 7.0 | 6.2 50 6.6 | 6.0 59 
"S See 0 7.6 | 7.6 0 6.8 | 6.8 0 
2.5 | 2.5 2.5 | 2.5 0 
3.0 | 3.0 105 3.0 | 2.8 50 3.0 | 3.0 0 
$.5 | 3.5 402 3.5 | 42 505 3.5 | 4.4 195 
z 40] ЕЗ 507 4.0 | 3.8 337 4.0 | 4.0 | 316 
81 45 | 5.6 414 4.2 | 4.0 320 42 | 4.0 | 307 
e| 5.0 | 5.3 441 4.9 | 47 303 49 | 48 | 304 
8 5.3 | 5.0 378 52 | 5.0 | 260 
&| 5.5 | 5.4 373 5.5 | 4.9 376 53.1 61 273 
ШІ 6.0 | 4.5 410 6.0 | 5.0 395 6.0 | 5.0 | 243 
6.5 | 4.7 374 6.5 | 4.8 244 65 | 5.0 | 205 
1.0 | 52 208 та 827 137 6.8 | 5.2 119 
7.4 | T.& 0 Te 135 0 7.5 | 7.5 0 
This species tends to increase the active acidity of the solutions 
in which it grows. In every case in the Richards' solution the 
acidity is slightly increased, usually less than 1 Py unit. In the 
peptone solution, with a few exceptions in the more acid range, 
is tendency persists, the amount of increase, as in the Richard’s 
solution, being less than 1 unit. Comparing the 2 solutions, 
however, the increase is greater in the peptone solution. 
When comparing the growth in the 2 media it becomes evident 
that the peptone solution is much the better. With peptone as 
the source of nitrogen, Polystictus versicolor produces some 5 to 
6 times as much mat as when an inorganic salt is the source of 
nitrogen. The range of growth in the peptone solution is not 
materially widened on the alkaline side except at 35° C., but on 
the acid side it is markedly widened for 15° C. and 35° C. For 
25° C. it remains the same in both solutions. It is evident that 
