Sept. 15, 1925 
Plate Counts of Soil Microorganisms 
507 
Table IV .—Results of frequent platings 
Date 
Mean 
tem¬ 
pera¬ 
ture 
W. 
H. C. 
Square 
No. 
l 
Millions per 
gram 
Date 
Mean 
tem¬ 
pera¬ 
ture 
W. 
H. C. 
Square 
No. 
Millions per gram 
H. 
V. 
S.E. 
M. S. 
E. A. 
Per 
Per 
°F. 
cent 
°F. 
cent 
July 26.— 
72 
25 
1 
29.2 
27.2 
Aug. 28... 
75 
33 
47 
26.7 
3.0 
20.1 
2 
27.5 
17.4 
48 
28.7 
5.1 
16.8 
27_ 
72 
25 
3 
29.5 
27.9 
29... 
74 
40 
49 
29.2 
3.9 
16.7 
4 
31.2 
19.1 
50 
19.7 
4.3 
18.5 
30_ 
76 
45 
5 
32.5 
27.9 
30... 
74 
41 
51 
28.6 
5.4 
21.9 
6 
38.5 
25.0 ' 
52 
26.1 
5.2 
20.4 
31_ 
69 
53 
7 
39.3 
34.4 
31... 
74 
45 
53 
24.4 
5.4 
17.0 
8 
30.5 
32.9 
54 
29.2 
5.7 
22.0 
Aug. 1... 
67 
57 
9 
28.3 
36.2 
Sept. 1_ 
73 
40 
55 
16.4 
2.3 
17.0 
10 
28.1 
30.3 
56 
22.0 
3.3 
20.1 
2_ 
75 
60 
11 
32.9 
29.1 
4_ 
78 
40 
57 
19.7 
2.3 
16.7 
12 
25.1 
25.1 
58 
20.0 
1.8 
19.0 
3.. 
82 
47 
13 
33.3 
30.5 
5—. 
73 
41 
59 
25.7 
5.3 
19.5 
14 
36.5 
33.5 
60 
24.6 
5.0 
17.1 
4.. 
82 
50 
15 
30.4 
32.6 
6_— 
68 
60 
1 
27.8 
3.1 
29.4 
16 
28.1 
36.0 
2 
24.4 
2.1 
27.2 
6__ 
81 
43 
17 
30.5 
29.6 
7.... 
74 
60 
3 
27.5 
2.2 
25.2 
18 
30.6 
. 4 
32.3 
2.0 
27.5 
7_ 
84 
43 
19 
26.6 
23.6 
8.... 
72 
55 
5 
24.3 
3.2 
20.8 
20 
35.3 
21.0 
6 
29.7 
4.4 
19.0 
10--.. 
65 
50 
7 
24.0 
3.7 
21.7 
Average. 
31.2 
28.5 
8 
26.7 
3.4 
18.1 
11 
65 
50 
9 
25.1 
4. 5 
18.4 
S.E. 
M. S. 
10 
21.8 
4.4 
17.8 
12—. 
71 
48 
11 
26.1 
5.4 
20.9 
Aug. 13.. 
74 
43 
21 
29.0 
12.6 
12 
25.0 
6.0 
18.2 
22 
31.8 
15.5 
13-..- 
70 
43 
13 
23.8 
4.7 
27.5 
14.. 
74 
37 
23 
26.7 
11.7 
14 
33.7 
5.4 
23.6 
24 
23.8 
9.0 
14— 
59 
43 
15 
25.1 
8.5 
26.8 
15_ 
80 
37 
25 
25.2 
5.6 
16 
27.4 
9.2 
23.6 
26 
26.5 
6.0 
15-.-. 
57 
40 
17 
27.8 
4.4 
25.1 
16_ 
73 
37 
27 
24.4 
9.8 
18 
21.8 
5.8 
17.5 
28 
34.0 
11.4 
17—. 
58 
37 
19 
30.4 
8.1 
25.0 
17.. 
65 
37 
29 
25.8 
7.0 
20 
20.9 
6.6 
16.5 
30 
21.3 
6.5 
18..- 
60 
32 
21 
16.6 
3.5 
20.2 
18__ 
67 
63 
31 
31.5 
7.5 
22 
21.7 
3.9 
17.8 
32 
38.5 
7.4 
19- 
74 
33 
23 
24.4 
5.8 
18.1 
20—•_.. 
74 
47 
33 
30.4 
5.7 
24 
21.6 
7.7 
18.1 
34 
31.5 
8.0 
21_ 
76 
47 
35 
30.0 
5.8 
Average 
25.0 
4.6 
20.7 
36 
30.5 
6.6 
99 
65 
43 
37 
34.6 
15.0 
Average 
72 
44 
28.0 
38 
31.7 
8.2 
23_ 
62 
40 
39 
33.9 
7.0 
40 
35.7 
8.5 
24.. .. 
66 
45 
41 
30.4 
6.4 
42 
32.0 
4.4 
25.— 
70 
47 
43 
29.9 
5.1 
44 
30.3 
5.1 
27_ 
76 
43 
45 
33.4 
5.2 
46 
30.2 
5.2 
Average. 
30.1 
8.0 
a h.= horizontal sampling. F = vertical sampling. S. E.= soil extract agar. M. S.= mannite salts 
agar. E. A.= egg albumen agar. W. H. C.= water-holding capacity. 
In plating another series of samples (Nos. 47 to 60 and 1 to 24), 
taken from adjoining squares on August 28 to September 19, egg- 
albumen agar (E. A.) was also used. The formula of this substrate 
as given by Waksman ( 13 ) is as follows: K 2 HP0 4 0.5 gm., MgS0 4 
0.2 gm., dextrose 10 gms., Fe 2 (S0 4 ) 3 trace, and agar 15 gms., dissolved 
in 1,000 c. c. distilled water; then 0.25 gm. egg albumen added, dis¬ 
solved in 0.1 NaOH. The counts obtained on the three media are 
recorded in the third part of Table IV. During the progress of these 
tests several batches of the three media were made up and found to 
be uniform. The Ph of each was within 0.2 of neutrality after 
sterilization. 
