248 
WILLIAM J. ROBBINS 
K2SO4: and Na2S0i. — In this series Penicillium camemhertii was 
grown in various concentrations of K2SO4 or Na2S04. Incubation 
of cultures was made in the dark at 25° C. The data summarized in 
Table V are the averages of triplicate cultures. 
From the data in Table V it may be noted that with K2SO4 and 
Na2S04 much the same effect results as with the chlorides of the . 
same bases. An inhibition in the actual amount of starch digested 
is produced even by a concentration of M/ioo,ooo. The effect of 
increasing concentration of the salts on the digestion is not so evident 
as with the chlorides. The M/iooo concentrations are clear excep- 
tions, the digestion being increased over M/i 0,000 in both cases and 
in both weeks. This would appear to be a real effect, not one due to 
errors in determination. It can also be observed in this case that 
the K2SO4 has a greater inhibitory effect on digestion than the Na2S04. 
This is shown in every case but one, the M/ioo,ooo concentrations at 
the end of two weeks, in which the difference is very slight. 
KNO3 and NaNOs. — Penicillium camemhertii was grown in this 
case in the concentrations of KNO3 or NaNOs noted in Table VI. 
The cultural conditions were those already noted. The results given 
in Table VI are the averages of triplicate cultures : 
Table VI 
KNOz and NaNO-, 
Soluble Starch in 
Dura- 
tion in 
Days 
Original 
Starch Con- 
tent(Mg. 
per 20 Cc.) 
Starch Con- 
tent After 
Digestion 
(Mg. per 20 
Cc.) 
Starch Di- 
gested (Mg. 
per 20 Cc.) 
Dry Weight 
of Mycelium 
(Mg.) 
Mg. of 
Starch Di- 
gested per 
Mg. of Dry 
Weight 
M/iooo KNO3 
7 
I40.9± .9 
I2.9±3.i 
128.0 
i5-7±] 
•7 
8.1 
M/io,ooo KNO3 
7 
i374± -I 
53.8±3.6 
83.6 
9.4± 
•3 
8.9 
M/ioo,ooo KNO3. . . 
7 
I38.7± .1 
74.1 ±2.2 
64.6 
3-7± 
.1 
17-5 
Water treated with 
carbon black 
7 
I43.i±i.i 
68.4± .5 
74-7 
3-7± 
.1 
20.2 
M/ioo,ooo NaNOs. . 
7 
I36.4± .1 
66.i=bi.4 
70-3 
4.o± 
.1 
17.6 
M/io,ooo NaNOs. . . 
7 
I37.8± .8 
47-7±i-3 
90.1 
7.6=h 
•3 
II. 8 
M/iooo NaNOs 
7 
I3i.8± .1 
I3.i± .8 
118. 7 
7.2± 
.1 
16.5 
M/iooo KNO3 
14 
140.9 ± .9 
Complete 
digestion 
32.1=1= 
•4 
M/io,ooo KNO. 
14 
i374± .1 
io.7±i.5 
126.7 
I2.8=fc 
.1 
9.9 
M/ioo,ooo KNO3. . . 
14 
i38.7± .1 
36.1 ± .8 
102.6 
5-3 
19-3 
Water treated with 
carbon black 
14 
i43.i±i.i 
34-3± .6 
108.8 
4-7 
23.1 
M/ioo,ooo NaNOa. . 
14 
I36.4± .1 
24.9±2.0 
111.5 
5-3± 
.1 
21.0 
M/io,ooo NaNOg. . . 
14 
i37-8± .8 
9.o± .8 
128.8 
10. Orb 
.2 
12.9 
M/iooo NaNOs 
14 
I3i.8± .1 
Complete digestion 
i3-5± 
.2 
