1921] 
KARRER—H-ION CONCENTRATION AND AMYLASE ACTION 89 
solution having an initial of Pa 3.0 and for Colletotrichum in a 
medium of Py, 8.2. Intracellular amylase accumulated most 
abundantly in culture solutions of P4 3.0 and 8.2 in the cases of 
Fusarium and Colletotrichum respectively, while natural Czapek’s 
solution was most beneficial in the case of Penicilliwm. 
With Fusarium, the greatest amount of total amylase accumu- 
lation was in Czapek's solution (fig. 12 and table vr). There was 
10 
8 
c* d 
<= = 
o 
ES x 
a ^4 
3 v 
& 
2 
A, AS S 7 9 
Fig. 10. Action of pant Fig. 11. Action of extracellular 
(——) and intracellular (- - -) am ) and intracellular (- - -) amylase 
produced by  Penicillium "LH produced by Penicillium italicum 
grown in Czapek's solution of Pg 3.0. grown in Czapek’s solution of Pg 4.5. 
slightly less in Czapek's solution having an H-ion concentration 
of Pa 3, and a gradual decrease occurred in Series 3, 4, and 5, 
respectively. The decrease on the alkaline side may have been 
due to several factors; either the alkalinity produced less se- 
cretion or the amylase was inactivated by these concentrations 
as it was produced. The amount of mycelium formed does not 
offer an explanation, since the dry weights of the fungous mats 
in the case of Series 5 were slightly more than in Series 1. How- 
