246 
WILLIAM J. ROBBINS 
present singly in solution, on the growth of Penicillium camemhertii 
and on the digestion of starch by that fungus, was determined after 
the methods given above. 
KCl and NaCl. — In this experiment various concentrations of 
KCl or NaCl were used. The fungus was grown in the dark at 25° C, 
and the amount of starch digested was determined at the end of one 
and of two weeks. The results summarized in Table IV are the 
averages for triplicate cultures. Where no probable error is given 
for these values, it is less than o.i mg. 
Table IV 
KCl and NaCl 
Soluble Starch in 
Dura- 
tion 
in Days 
Original 
Starch Content 
(Mg. per 
20 Cc.) 
Starch Content 
after Digestion 
(Mg. per 
20 Cc.) 
Starch 
Digested 
(Mg. per 
20 Cc) 
Dry Weight 
of 
Mycelium 
Mg. of Starch 
Digested per 
Mg. of Dry 
Weight 
M/iooo KCl 
7 
i34-i± .8 
103. 8=t .4 
30.3± -9 
20.2=hl.4 
3M/io,ooo KCl . . . 
7 
i33-i± -9 
99-5±i-3 
33.6d=i.6 
i.4=t.i 
24.0±2.0 
M/ioo,ooo KCl . . . 
7 
i33-5± -I 
IOI.2±I.4 
32.3±i4 
2I.5=fcl.6 
Water treated with 
carbon black. . . . 
7 
I45.6±i.3 
ioi.7=ti.6 
43.9d=2.o 
i.5±.i 
29.2=1=2.3 
M/ioo,ooo NaCl . . 
7 
i43.8±i.o 
I03.4± .6 
40.4=ti.i 
1.3 
3i.o±2.5 
M/io,ooo NaCl . . . 
7 
140. 8zb .1 
104.1=1=3.0 
36.7d=3.o 
i.5±-i 
24.4=1=3.8 
M/iooo NaCl 
7 
142.9 
I03.7± .9 
39-2 ± .9 
i.5±-i 
26.i±i.8 
M/iooo KCl 
14 
i34.id= .8 
67-3± -7 
66.8=ti.i 
2.0 
33.4=1=1.8 
3M/io,ooo KCl . . . 
14 
i33-i± -9 
73-3± -6 
59.8±i.i 
T.8 
33.2=t2.o 
M/ioo,ooo KCl . . . 
14 
i33-5± .1 
7i.i=h .5 
62.4± .5 
i.7±.i 
37.0±2.2 
Water treated with 
carbon black. . . . 
14 
I45.6±i.3 
58.5±i- 
87.i=ti.6 
2.2d=.I 
39.6±i.9 
M/ioo,ooo NaCl . . 
14 
143.8=1=1.0 
67.4±i-5 
76.4±i.8 
2.2 d=. I 
34.7=1=1.8 
M/io,ooo NaCl . . . 
14 
I40.8d- .1 
69.2=1=1.8 
7i.6±i.8 
2.I=t.I 
34-i±i-5 
M/iooo NaCl 
14 
142.9 
73-5±2.3 
69.4=t2.3 
2.2=t:.I 
35.1=1=1.8 
In Table IV the probable errors have been calculated for the 
"starch digested," which is the difference of the two quantities 
"original starch content" and "starch content after digestion." 
They have also been calculated for the "mg. of starch digested per 
mg. of dry weight," which is the quotient of the starch digested in a 
culture divided by the dry weight of the mycelium produced in the 
same culture. In all later tables this calculation has not been made, 
though the probable errors are given for the averages of the deter- 
minations made on the original starch content, the starch content 
after digestion, and the dry weight of the mycelium. 
From the data given in Table IV, it can be observed that, in general, 
KCl and NaCl decrease the amount of starch digested by Penicillium 
camemhertii. This inhibition is evident in the case of both KCl and 
