BACTERIOLOGICAL STUDY OF EETAIL ICE CEEAM, 
19 
Table 12. — Bacteria of the colon group found in ice cream as determined on litmus- 
lactose-asparagin agar. 
Sample 
Manu- 
fac- 
turer. 
B. coll 
per cubic 
Sample 
Manu- 
B. coli 
per cubic 
Sample 
Manu- 
B. coli 
per cubic 
No. 
centi- 
meter. 
No. 
turer. 
centi- 
meter. 
No. 
turer. 
centi- 
meter. 
32 
A 
120 
160 
C 
10 
49 
K 
120, 000 
33 
A 
86,000 
161 
C 
30 
50 
K 
75,000 
37 
A 
100 
186 
C 
140 
51 
K 
300, 000 
38 
A 
100 
187 
C 
700 
79 
Ki 
150 
39 
A 
8,000 
188 
C 
50 
80 
Ki 
40 
40 
A 
900 
44 
D 
2,400 
81 
Ki 
30 
83 
A 
420 
45 
D 
7,700 
82 
Ki 
40 
124 
A 
80 
89 
D 
4,600 
134 
Ki 
i 
125 
A 
10 
52 
E 
600,000 
135 
Ki 
20 
138 
A 
10 
53 
E 
47, 000 
136 
Ki 
10 
139 
A 
10 
54 
E 
5,600 
137 
Ki 
10 
143 
A 
10 
140 
E 
30 
70 
M 
1,730 
151 
A 
10 
141 
E 
10 
71 
M 
550 
152 
A 
40 
142 
E 
400 
72 
M 
2,530 
153 
A 
10 
67 
F 
3,900 
73 
M 
2,350 
168 
A 
50 
68 
F 
3,900 
84 

7,600 
169 
A 
30 
69 
F 
5,000 
87 

12,200 
31 
B 
15,400 
146 
F 
100 
62 
L 
11,900 
41 
B 
2,500- 
147 
F 
10 
63 
L 
3,000 
42 
B 
17,100 
74 
G 
20 
64 
L 
3,000 
43 
B 
2,800 
75 
G 
10 
65 
L 
123,000 
126 
B 
300 
76 
G 
100 
66 
P 
3,000 
127 
B 
100 
77 
G 
230 
144 
Q 
20 
128 
B 
200 
78 
G 
820 
145 
Q 
20 
133 
B 
1,000 
148 
G 
120 
132 
R 
10 
158 
B 
2,900 
149 
G 
50 
175 
S 
300 
162 
B 
10 
150 
G 
200 
176 
s 
800 
163 
B 
400 
59 
H 
6,500 
177 
s 
600 
164 
B 
700 
60 
H 
1,200 
171 
T 
90 
165 
B 
10 
61 
H 
15,000 
172 
T 
800 
166 
B 
1,400 
157 
H 
10 
173 
T 
1,200 
167 
B 
1,800 
55 
5,600 
174 
T 
100 
170 
B 
14,000 
56 
7,200 
178 
U 
1,400 
46 
C 
700 
57 
400 
179 
U 
4,000 
47 
C 
2,400 
58 
12,000 
180 
w 
2,700 
85 
C 
13,300 
154 
10 
181 
w 
300 
86 
C 
13,500 
155 
900 
182 
w 
700 
90 
C 
6,000 
156 
300 
183 
X 
4,100 
91 
C 
8,300 
88 
3,100 
184 
X 
30 
159 
C 
40 
48 
K 
108,000 
185 
X 
300 
1 In •& dilution. 
During this series of examinations the suspected colon colonies 
on the asparagin-agar plates from 19 samples were picked off and 
inoculated into lactose-broth fermentation tubes. After incuba- 
tion for 48 hours at 37° C. (97.5° F.) the tubes were examined for 
the presence of gas. The number of cultures picked off and the num- 
ber showing gas, together with the percentage of the cultures suspected 
of being gas formers from the examination of the plate, are shown in 
Table 11. An examination of the results shows that in 10 of the 19 
plates studied all the colonies considered gas formers developed gas 
in fermentation tubes. In other words, 100 per cent were gas formers. 
Among the other 9 samples the percentage ranged from 87.17 to 100 
per cent. This shows that it is possible to detect quite accurately 
any colonies of gas-forming bacteria on litmus-lactose-asparagin 
agar. 
One hundred and twenty samples of ice cream were examined 
during the summer and winter seasons by the use of the above-men- 
tioned medium. The results are tabulated in Table 12. Gas-forming 
