24 
BULLETIN S39, U. S. DEPARTMENT OF AGRICULTURE. 
show the remarkable difference in growth of organisms of the colon- 
aerogenes group in milk held at 50° F. (10° C), compared with 70° F. 
(21° C). While there is some indication of slight growth in a few of 
the samples held at 50° F. (10° C), there was the rapid multiplication 
of the organisms in milk held at 70° F. (21° C), the average colon 
count in 20 samples held for 24 hours at this temperature being 
7,385,500 per cubic centimeter. 
Table 13. — Growth of organisms of colon-aerogenes group at 50° F. {10° C.) and 70° F. 
(21.1° C). 
Sample 
No. 
Total count. 
Colon count. 1 
Held for 
Held for 24 
Fresh. 
Fresh. 
24 hours 
at 50° F- 
hours at 
70° F. 
(10° C). 
(21.1° C). 
1 
225,000 

100 
i 
180, 000 
2 
1, 140, 000 
2S,400 
83,000 
55, 500, 000 
3 
270,000 

200 
2, 600, 000 
4 
680, 000 


2, 350, 000 
5 
1, 080, 000 


3, 400, 000 
6 
490, 000 

800 
5, 100, 000 
7 
850,000 
900 
1,300 
8, 300, 000 
8 
840, 000 

200 
2, 700, 000 
9 
1, 450, 000 

600 
2, 520. 000 
10 
2,400,000 


12, 800, 000 
11 
1, 950, 000 


22, 000, 000 
12 
260, 000 


1, 250, 000 
13 
610, 000 
2,000 
600 
15,300.000 
14 
340, 000 


830.000 
15 
630, 000 


1, J 70, 000 
16 
179, 000 


1, 180, 000 
17 
366, 000 


6,400,000 
18 
304, 000 


120,000 
19 
460, 000 


1,810,000 
20 
620, 000 

400 
2,200,000 
i indicates none in T ^ of a cubic centimeter. 
Further studies on the growth of organisms of the colon-aerogenes 
group at different temperatures are shown in Table 14. Three dif- 
ferent sets of conditions were used so as to determine the subsequent 
growth in three distinct grades of fresh milk. Special attention is 
called to the colon counts after the milk had been held for 6 hours at 
86° F. (30° C.). Among the 22 samples" of milk produced in the 
dirty barn and handled in sterilized utensils there was practically 
no increase in the colon count after 6 hours at 86° F. (30° C), but 
after 24 hours at the same temperature the colon count had reached 
the high figure of 63,279,545 per cubic centimeter. Twenty-six 
samples produced in the dirty barn and handled in unsterilized 
utensils showed after 6 hours a distinct increase in the colon count 
in most of the samples, and after 24 hours the colon count averaged 
about 24,000,000 per cubic centimeter. 
Similar increases occurred among the 20 samples produced in a 
dirty barn and handled in unsterilized utensils which had not been 
washed until 8 hours after milking. The average colon count of the 
fresh milk was 595 per cubic centimeter. After 6 hours, at 86° F. 
(30° C.) the average count had increased to 37,525, while after 24 
