l8 •. C. A. LUDWIG 
First Trial 
Second Trial 
Third Trial 
Species 
Gas Cone. 
3d 
6th 
Qth 
i2th 
3d 
6th 
9th 
i2th 
3d 
6th 
9th 
i2th 
Day 
Day 
Day 
Dayl 
Day 
Day 
Day 
Day2 
Day 
Day 
Day 
Day2 
Air 
21 
55 
92 

8.5 
43 
73 
862 
14 
42 
73 
902 
5 /o 

■ — ■ 
— ■ 

II 
42 
71 
87 
8 
28 
54 
83 
io% 

— 

— ' 
7-5 
29 
51 
73 
II 
32 
56 
87 
o <^ 
25% 
9 
12 
34 
60 
5.5 
22 
39 
67 
7-5 
22 
38 
71 
50% 
7 
9 
21 
45 
1.5 
10 
17 
37 
0 
9 
25 
42 
75% 
1-5 
6 
II 
30 
0 
2 
6 
27 
0 
2 
7-5 
34 
100% 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
Air 
24 
45 
66 
90 
17 
47 
73 
95^ 
22 
44 
70 
902 
5% 
15 
44 
71 
902 
20 
43 
66 
912 
10% 
14 
43 
70 
92 
19 
42 
64 
88 
25% 
23 
44 
65 
87 
14 
41 
66 
85 
18 
40 
62 
86 
50% 
20 
42 
63 
87 
12 
36 
60 
82 
14 
34 
55 
81 
75% 
16 
39 
54 
76 
7 
23 
38 
59 
5 
25 
40 
66 
100% 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
Air 
29 
54 
80 
912 
20 
55 
84 
882 
22 
50 
75 
902 
5% 
19 
52 
80 
882 
22 
50 
74 
902 
'IS 
10% 
17 
50 
78 
882 
24 
47 
70 
902 
25% 
18 
37 
58 
82 
12 
39 
68 
902 
24 
44 
63 
85 
50% 
15 
29 
44 
67 
9 
26 
43 
69 
10 
23 
35 
57 
75% 
10 
19 
30 
53 
5 
16 
29 
55 
6.5 
'I 
23 
52 
100% 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
radii not in a straight line was taken instead of the diameter). The 
medium used was potato glucose (2 percent) agar (3 percent). It was 
poured into the plates and the fungus inoculated into the center of 
the freshly hardened layer of agar. The plates were then sealed under 
bell jars and the gas introduced in the usual way. The apparatus was 
taken down every third day to record data. In the case of the test 
with pure gas the gas passed constantly through the jar containing 
the cultures. This dried the agar in the first trial, and it was thought 
that the dry condition of the agar might have had something to do 
with the failure of the fungi to grow after the restoration to the air. 
In the second and third trials, therefore, the gas was passed over water 
in a bottle before entering the jar; and this prevented evaporation of 
the moisture in the agar. 
The accompanying table records the organisms, the treatments, 
and the results obtained, the measurements being diameters of colonies 
in millimeters. It can be seen from this that the lower limit of toxicity, 
or at least considerable retardation of growth, is between 10 percent 
and 25 percent in most of the species; but in one, Fusarium radicicola, 
it is difficult to locate, and is higher than for the rest of the 
