IOWA ACADEMY OF SCIENCES. 
141 
The table which follows shows the data accumulated: 
Total number 
per c. c. 
ACID CLASS. 
NO EFFECT 
ON MILK. 
ENYZME PRO- 
DUCING. 
Dilution. 
MEDIA USED. 
Number 
per c. c. 
Per cent, 
of whole. 
N umber 
per c. c. 
1 Per cent. 
| of whole. 1 
Number 
per c. c. 
Per cent, 
of whole. 
6,960 
169, 040 
Milk. 
6,960 
494, 160 
6, 720 
Peptone Agar 
127, 680 
None 
None 
89, 37o 
70 
38, 304 
3 o 
Milk. 
6,720 
Lactose Agar 
329, 280 
1x8, 54c 
36 
164, 64c 
5o 
46,000 
M 
6,720 
Peptone Gelatin. . . 
255,36o 
17,875 
7 
153,216 
60 
85, 120 
33 
1,583 
Peptone Agar 
136, 138 
12, 252 
9 
103, 463 
72 
20, 420 
i5 
Milk. 
i ,583 
Lactose Agar 
1,600,4x3 
928,239 
58 
576, 148 
36 
96,024 
6 
i ,583 
Peptone Gelatin... 
1, 302, 809 
547, 179 
42 
547, 179 
42 
208, 459 
16 
3,565 
Peptone Agar 
563, 2 71 
None 
None 
490,045 
87 
73, 225 
i 3 
Milk. 
3,565 
Lactose Agar 
I, 71 1, 200 
427, 800 
25 
1, 163,600 
68 
119,784 
7 
3, 565 
Peptone Gelatin. . . 
I, 158,625 
173,793 
15 
822, 623 
7i 
162, 207 
14 
30, 000 
Peptone Agar 
i . 260, 000 
138, 600 
11 
970, 200 
77 
15 1. 200 
12 
Buttermilk. 
30,000 
Lactose Agar 
26, 180, 000 
8, 115, 81c 
3i 
16, 493, 000 
63 
1, 57o, 000 
6 
30, 000 
Peptone Gelatin.. 
12, 320,000 
2, 587,000 
21 
8,254,000 
67 
1,478, 000 
12 
30,000 
Lactose Gelatin. . . 
19, 320,000 
8,887,200 
46 
8, 887, 200 
46 
1 . 540, 000 
8 
1 - , 960 
Lactose Agar 
19,350,000 
230, 500 
43 
8,230,500 
43 
2, 709, 000 
14 
Whey from 
Edam cheese 
10, 960 
Peptone Gelatin.. 
5, 224,000 
574, 660 
11 
3. 656,000 
7o 
992, 500 
19 
10, 960 
Lactose Gelatin. .. 
13,330,000 
2,932,600 
22 
9,597,6oo 
72 
799, 800 
6 
26, 500 
Lactose Agar 
28, 487, 500 
21, 365, 625 
75 
1,709,250 
19 
5,412,600 
6 
Sour milk. 
26, Sco 
Peptone Gelatin.. 
18, 671, 000 
1, 867, 100 
10 
1,475, 600 
80 
1, 867, IOC 
10 
26, 500 
Lactose Gelatin . . . 
36, 550,000 
29, 240, 000 
80 
4, 386,000 
12 
2,924,000 
~8~ 
3,900 
Lactose Agar 
9,087,000 
4, 180,000 
46 
4, 180,000 
46 
726, 960 
8 
Milk. 
3, 900 
Peptone Gelatin.. 
1,930,500 
250,960 
13 
1,274.130 
66 
396, 400 
21 
1, 900 
Lactose Gelatin. . . 
9, 360, 000 
5,6x6,000 
60 
2, 527,000 
27 
1, 216,000 
13 
The peptone gelatin was made up according to common 
methods, using 10 per cent, gelatine, and making it neutral 
to phenolphtalien with sodium hydroxide. The peptone 
agar contained 1.7 per cent, agar, neutralized in the same 
manner. The lactose media had 2 per cent lactose added 
after filtering. 
It is to be remarked, that the quantitative estimates of the 
number of bacteria are estimates and not exact determina- 
tions, the nearest we can approach to accuracy by present 
methods. Anyone familiar with such work is aware that 
