1921] , 
KARRER—H-ION CONCENTRATION AND AMYLASE ACTION 73 
PREPARATION OF CULTURES FOR ENZYME STUDIES 
Chemicals and glassware.—In all of the following experiments 
the highest purity chemicals and water redistilled from a trace 
of potassium permanganate and a few drops of sulphurie acid 
were used unless otherwise specified. 'The doubly distilled 
water gave an H-ion concentration of Py 5.2-5.6. The glassware 
was chemically cleaned and rinsed with distilled and doubly 
distilled water except in the experiments for the sugar determi- 
nations where distilled water was employed. 
The fungi were grown in 300-cc. Pyrex flasks, and the cul- 
ture solution was prepared according to the following modifi- 
cation of Czapek’s solution: 
O0 1 2M Cr re ET 5 
KIHEPO,........:- Seep ees 1.0 gms 
KCl......... S ee 5 gms 
Pe80,..........- OD SERENA .01 gms. 
EDEN age c 2.0 gms. 
Soluble starch. .... <5 3 24 PER 5.0 gms. 
Cane SUMED... «6... AG Vv VERAT IS .05 gms 
Wster........ a eee 1000 cc 
The monobasic potassium phosphate was extremely acid and 
therefore it was recrystallized until a solution of M/15 gave a 
reaction of Pa 4.5. Starch was added as the source of energy, 
since Dox (710) and also later investigators have shown that 
its presence in culture solutions increases the production of 
amylase. It has been shown, further, that the presence of a 
trace of sugar, which increases the initial growth, is beneficial 
to the formation of amylase. 
A range of Pa 1.8-9.4 was obtained in this culture solution 
by the addition of regulated amounts of N/20 KOH and N/5 
HCl aecording to the method described by Karrer and Webb 
(20). From their curve, the amounts of acid and alkali neces- 
sary to bring the solution to the required H-ion concentration 
can be computed. The solutions containing 5 and 10 cc. of N/20 
KOH all showed a slight precipitate. Fifty flasks containing 
a solution of the same H-ion concentration constituted a series. 
The flasks were inoculated with a loopful of spore suspension, 
one uninoculated flask being kept as a control Five series 
with the culture solution adjusted to Py 3.0, Px 4.5, Pu 7.0, 
