SIGNIFICANCE OF COLON COUNT IN MILK. 
17 
relation between the quantity of manure and the colon count. This 
is undoubtedly due to the variable number of such organisms found 
in cow feces, and to the different degrees of such contamination 
introduced through unsterilized utensils. 
The results thus far presented show very clearly that unsterilized 
utensils play a prominent part in the contamination of milk with 
organisms of the colon-aerogenes group. To emphasize this point 
an experiment was conducted in which the milk from three cows went 
into sterile utensils while that from three others went into unsterilized 
utensils which had been allowed to stand for 24 hours before washing. 
All six cows were clean and were kept in a clean barn, and the only 
chance for difference in the contamination of the milk was due to the 
unsterilized utensils. The results in Table 9 show that in the milk 
handled in sterilized utensils there were no organisms of the colon- 
aerogenes group present in 1/100 of a cubic centimeter, while all the 
samples of milk handled in unsterilized utensils showed the pres- 
ence of these organisms, ranging from 1,100 to 350,000, and averag- 
ing 80,650 per cubic centimeter in the fresh milk. This, of course, 
represents contamination from unsterilized utensils which were 
handled in an unusual manner, but it serves to emphasize the impor- 
tance of sterilized utensils in connection with the colon count. 
Table 9. — Effect of sterilized utensils on colon count. 
Sample No. 
. Sterilized utensils. 
Utensils not sterilized. 
and not washed for 24 
hours. 
Total 
count. 
Colon 
count. 1 
Total count. 
Colon 
count. 
1 
2 
3 
4 
5 
6 
7 
8 
Average... 
17, 100 
4,600 
7,300 
5,700 
3,900 
4,300 
, 10, 200 
6,300 








2, 050, 000 
2, 800, 000 
2,320,000 
2,210,000 
254, 000 
680,000 
450, 000 
365, 000 
91, 000 
72, 000 
120, 000 
350, 000 
1,100 
1,400 
5,200 
4,500 
7,425 
1,391,125 
80, 650 
1 indicates none in 1/100 of a cubic centimeter. 
At this point it is possible to answer the question " How many 
organisms of the colon-aerogenes group can be introduced during 
milking?" The answer is, not over 2,000 per cubic centimeter, and 
is based on the examination of 254 samples produced under both 
clean and unusually filthy conditions, only one sample of which 
showed a colon count of over 2,000 per cubic centimeter in fresh 
milk. A summary of these counts is shown in Table 7 and also 
in figure 1. If this is the maximum number of organisms of the 
75649°— 18— Bull. 739 3 
