[Vor. 11 A 
68 ANNALS OF THE MISSOURI BOTANICAL GARDEN 
` Та the peptone solution there is a tendency to decrease the active 
acidity at both 15° C. and 35° C. and to increase it at 25° C. 
At this last temperature, for solutions within the initial Рн range 
4.0-6.5, the final Ру varies from 4.0 to 4.6. Growth at Pg 3.5 
tends to decrease the acidity to 4.2. On the other hand, at 35° 
C. the initial Рр range 4.0-6.0 changes to 6.0-6.3. There is an 
Fig. 11. Pleurotus ostreatus in Richards’ solution. Es 
increase in the acidity at Ру 6.5 to a final value of 4.6, and à. — 
decrease at Py 3.5 to a final value of P4 4.8. When one compares 22 
the similarity of the growth curves at 25° C. and 35° C. these | 
results are rather unexpected. Throughout the Ру range 40-70 © 
the decrease in the acidity at 15° C. is less marked than at 85° С. | 
Upon comparing the growth curves for the 2 solutions, it be- | 
comes evident that 25° C. is the optimum temperature of those | 
