SIGNIFICANCE OF COLON COUNT IN MILK. 
19 
Table 10.— Number of organisms of colon-aerogenes group introduced into fresh milk 
under abnormal conditions. 
Conditions. 
Sample 
No. 
Total 
count. 
Colon 
count. 
Per c. c. 
Per c. c. 
( 1 
18,900,000 
5,200.000 
2 
25,300,000 
3,600,000 
3 
16,500,000 
1,190,000 
4 
22,700,000 
5,100,000 
Utensils held 24 hours before washing; not sterilized. August 21 to 30, 
5 
6 
28, 200, 000 
33,000,000 
17,200,000 
33,500,000 
6,700,000 
1,620,000 
340,000 
690,000 
and September 8 to 17; air temperature 70° F. to 98° F. (21.1° C. to 
37.5° C.) 
7 
8 
9 
54,000,000 
1,780,000 
10 
65,000,000 
2,350,000 
11 
25,000,000 
1,190,000 
I 12 
2, 040, 000 
80,000 
1 
2,050,000 
91,000 
2 
2, 800, 000 
72,000 
October 3 to 12, 
75° F. (23.9° C). 
3 
4 
5 
2,320,000 
2,210,000 
680,000 
120,000 
350,000 
1,400 
6 
450,000 
5,200 
7 
365, 000 
4,500 
1 
1,010,000 
0) 
October 22 to 25, 
2 
3*0,000 
200 
60°F.(21.1°C). 
3 
690,000 
100 
I 4 
580,000 
300 
1 
270,000 
1,400 
Utensilsheld 24hours before washing; not sterilized. 
October 22 to 25, 
75° F. (23.9° C). 
2 
3 
560,000 
370,000 
500 
300 
4 
490,000 
163,000 
400 
1,200 
October 29 to No- 
2 
490,000 
2,200 
vember 5, 60° 
3 
410,000 
800 
F. (21.1° C.).... 
4 
288,000 
700 
5 
310,000 
100 
f 1 
1,100,000 
37,000 
October 29 to No- 
2 
225,000 
13,000 
vember 5, 86° 
i 3 
98,000 
400 
. F. (30° C.) 
4 
161,000 
300 
I 5 
42,000 
200 
i in 1/100 c. c. 
These results indicate that under abnormal conditions the colon 
count may be over 2,000 per cubic centimeter in fresh milk, but it is 
believed, in view of our experiments, that such exceptional condi- 
tions are seldom encountered. These high counts therefore do not 
detract from the value of the 2,000 maximum colon count per cubic 
centimeter, which has been set as the maximum contamination by 
organisms of the colon-aerogenes group in fresh milk. 
WHY ARE HIGH COLON COUNTS OFTEN FOUND IN RAW MILK? 
Assuming the correctness of the fact just established that fresh 
milk produced under normal conditions very rarely contains over 
2,000 organisms of the colon-aerogenes group per cubic centimeter, 
the question " Why are high colon counts often found in raw milkf ' 
can be answered by the statement that high colon counts in raw milk 
are due to growth which takes place between the time of production 
and that of consumption. 
If organisms of the colon-aerogenes group were not able to grow in 
milk the colon count would be of far greater value as an index of con- 
