SIGNIFICANCE OP COLON COUNT IN MILK. 
21 
cubic centimeter of milk and their average counts are given, together 
with the per cent of samples which did not show the colon-aerogenes 
group in this quantity of milk. Where more than one sample of a 
group showed colon organisms the range is also given. The colon 
counts represent the highest number determined on either litmus- 
lactose-asp ar agin agar or on Endo medium. 
Table 11. — Growth andfrequency of organisms of colon-aerogenes group at 50° F. (10° C. ) 
Num- 
ber of 
Conditions. 
Average 
total 
count. 
Colon count. 
sam- 
ples. 
Fresh. 
24 hours. 
20 
Barn clean, cows clean, 
utensils sterilized 
(A). 
Per c. c. 
4,245 
Per c. c. 
100 per cent- in 1/100 c. c. 
Per c. c. 
94.4 per cent—. 
5.6 per cent+. 
Average colon count, 300. 1 
34 
Barn dirty, cleaned 
once a week; cows 
dirty; utensils steril- 
ized (B). 
38,262 
94.1 per cent—. 
5.9 per cent-K 
Range, 100 to 300. 
Average colon count, 200. 
100 per cent—. 
23 
Same as B, but uten- 
sils not sterilized. 
161,083 
95.6 per cent—. 
4.4 per cent+. 
Average colon count, 400. 
100 per cent—. 
Num- 
ber of 
Conditions. 
Average 
total 
count. 
Colon count. 
sam- 
ples. 
48 hours. 
72 hours. 
96 hours. 
20 
Barn clean, cows 
clean, utensils 
sterilized (A). 
Per c. c. 
4,245 
Per c. c. 
94.4 per cent—. 
5.6 per cent+. 
Average colon count, 
3,200. 
Per c. c. 
83.3 per cent-. 
16.7 per cent+. 
Range,l,600to28,000. 
Average colon count, 
10,533. 
Per c. c. 
83.3 per cent-. 
16.7 per cent+. 
Range, l,600to 79,000. 
Average colon count, 
27,533. 
34 
Barn dirty,cleaned 
once a week; cows 
dirty; utensils 
sterilized (B). 
38,262 
95.6 per cent—. 
4.4 per cent+. 
Average colon count, 
1,900. 
95.6 per cent—. 
4.4 per cent+. 
Average colon count, 
3,200. 
54.2 per cent— . 
45.8 per cent +. 
Range, 2,000 to 
186,000. 
Average colon count, 
24,172. 
23 
Same as B , but uten- 
sils not sterilized. 
161,083 
94.7 per cent—. 
5.3 per cent+. 
Average colon count, 
11,600. 
83.3 percent-. 
16.7 per cent+. 
Range,4,500 to 12,500. 
Average colon count, 
8,100. 
55.5 per cent—. 
44.5 per cent-)-. 
Range,3,300 to 22,000. 
Average colon count, 
13,300. 
i Average colon count per cubic centimeter in samples showing them in ^ of a cubic centimeter and over. 
The average total count of 20 samples of milk produced under 
clean conditions was 4,245, indicating a high quality of milk, from a 
bacterial standpoint. No organisms of the colon-aerogenes group 
were found in 1/100 of a cubic centimeter in any of these samples 
when fresh. After 24 hours 94.4 per cent of the samples were still 
negative, while 5.6 per cent were positive. The same results were 
obtained at the end of 48 hours, only one sample showing organisms of 
