16 
BULLETIN 739, U. S. DEPARTMENT OF AGRICULTURE. 
were present in y^- of a cubic centimeter. Only 9 samples showed 
organisms of the colon-aerogenes group, and 8 of these ranged from 
100 to 2,000, while the other had a count of 28,000 per cubic centi- 
meter. Further study of the disks shows that there is no correlation 
between the quantity of manure and the colon count ; some samples 
having a considerable amount of sediment showed no organism of the 
colon-aerogenes group, while others with a considerably less amount 
showed several hundred per cubic centimeter. 
Keference to column C of figure 1 shows that about 72 per cent of 
the samples of milk produced under the conditions described did not 
contain any organisms of the colon-aerogenes group in -^ of a cubic 
centimeter. Table 8 gives the results of a series of samples in which 
larger quantities of milk were examined. It is evident that milk, 
when fresh, even though produced under extremely dirty conditions 
and handled in unsterilized utensils, contains only a few organisms of 
the colon group. Of the 38 samples, 11 showed no colon organisms in 
■£j of a cubic centimeter of milk, while in the remaining 27 samples 
the minimum colon count ranged from 3 to 75 per cubic centimeter. 
Table 8. — Small colon-aerogenes infection in fresh milk produced under dirty conditions. 
Sample 
Total 
Colon 
Sample 
Total 
Colon 
No. 
count. 
count. 1 
No. 
count. 
count. ! 
Per c. c. 
Per c. c. 
Per c. c. 
Per. c. c. 
1 
179,000 

20 
580,000 
5 
2 
180,000 

21 
620, 000 
50 
3 
182,000 
10 
22 
630, 000 

4 
190, 000 
5 
23 
680, 000 
50 
5 
225, 000 
10 
24 
750, 000 

6 
260,000 
10 
25 
790, 000 
75 
7 
270, 000 
10 
26 
820, 000 
8 
8 
295, 000 
8 
27 
840, 000 

9 
304, 000 
10 
28 
1,080,000 
10 
10 
318,000 
10 
29 
1, 120, 000 
10 
11 
320, 000 

30 
1, 170, 000 
8 
12 
340, 000 

31 
1,310,000 
3 
13 
366, 000 

32 
1,320,000 
3 
14 
450, 000 
5 
33 
1,440,000 
5 
15 
460, 000 

34 
1,450,000 

16 
490, 000 
3 
35 
1, 600, 000 

17 
490,000 
10 
36 
1,940,000 
10 
18 
497, 000 
8 
37 
1, 950, 000 
10 
19 
560,000 
75 
38 
2,400,000 
10 
i Cipher indicates no organisms of the colon-aerogenes group in x % cubic centimeter of milk. 
Additional sediment disks are shown in Plate III, the correspond- 
ing samples of which are also included in column D of figure 1 . In this 
case the utensils were not washed till 8 hours after milking, but 
otherwise the conditions were the same as in the previous experi- 
ment. Here, again, even with very large quantities of manure found 
in the milk, together with the increased possibilities of colon con- 
tamination from the unsterilized utensils, the colon count never 
ran over 2,000 per cubic centimeter when the milk was fresh. Plates 
I, II, and III show that under these conditions there is no definite 
