SIGNIFICANCE OF COLON COUNT IN MILK. 13 
A study was also made of 56 samples produced under conditions in 
which the cows were very dirty and the barn was cleaned only once 
or twice a week. The utensils were sterilized so that they would play 
no part in the contamination, thus demonstrating the extent of con- 
tamination by the colon-aerogenes group which might take place in a 
filthy barn. Of the 56 samples of milk produced under these condi- 
tions only 6, or 10.7 per cent, showed organisms of the colon-aerogenes 
group in 1/100 of a cubic centimeter. The range of these organisms 
was from 100 to 400 and averaged 183 per cubic centimeter. The 
average total count of the 56 samples was 36,541 per cubic centi- 
meter. This at first thought might seem low in view of the filthy 
conditions of production described. The work of Ayers, Cook; and 
Clemmer (1), however, has shown that large numbers of bacteria are 
not generally introduced through manurial filth even under extreme 
conditions, but come largely from unsterilized utensils. 
An analysis of 84 samples of milk produced under the same dirty 
conditions as previously described but with utensils which were not 
sterilized showed that 24 samples, or 28.6 per cent, contained organ- 
isms of the colon-aerogenes group in 1/100 cubic centimeter. The 
utensils in this case were washed in hot water containing washing 
powder within one hour after milking, rinsed in clean, cold water, and 
allowed to stand inverted until the next milking. The colon count 
of the 24 samples which showed positive results in 1/100 of a cubic centi- 
meter ranged from 100 to 28,400 per cubic centimeter. Only one 
sample ran over 2,000, that one being 28,400. Including this high 
count the average would be 1,717, while leaving out this one high 
count the average for the remaining 23 samples would be 557 per 
cubic centimeter. These figures indicate clearly that unsterilized 
utensils play a prominent part in contamination of milk by the colon- 
aerogenes group. It will be noted in Table 7 that in the milk pro- 
duced in unsterilized utensils the colon count was almost three times 
higher and the total count also higher than in the milk produced in 
sterilized utensils. In both cases the barn was equally dirty. 
The manner' in which the utensils are cleaned plays a very im- 
portant part in the contamination of milk by organisms of the colon- 
aerogenes group, which is clearly shown in the last line of Table 7. 
The milk was produced in the same dirty barn as just mentioned, but 
the drainings were allowed to remain in the utensils for 8 hours, after 
which they were washed in hot water containing washing powder. 
Of the 28 samples produced under this condition 20, or 71.4 per cent, 
showed colon bacilli in 1/ 100 of a cubic centimeter. They ranged from 
100 to 1,800, averaging 750 per cubic centimeter, and were no higher 
than in the milk produced in the previous experiment, in which 
the utensils were washed immediately, but a much greater percentage 
showed organisms of the colon-aerogenes group than in the previous 
case. 
