~SACTERIA IN THE DAIRY. 69 
Bec li RIAR NG TH Be DAD Y: 
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VII. SOME OBSERVATIONS OF THE NUMBER OF BACTERIA IN DAIRY 
PRODUCTSs* 
BY A. E. LOVELAND AND W. S. WATSON. 

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NUMBER OF BACTERIA IN MILK. 
‘ Within the last few years, with the improvement of methods 
and the discovery that milk may serve as the medium for trans- 
porting pathogenic (disease) germs, new interest has been aroused 
in the bacteriological study of milk. It has been found that 
the milk from a perfectly healthy cow, when entirely uncon- 
taminated, is absolutely sterile, z. ¢., contains no germs. But 
ordinary milk always contains bacteria, and as milk furnishes an 
excellent food medium for their development, they multiply very 
rapidly. The presence of a large number of germs does not 
necessarily imply that the milk is injurious, nor does a small 
number of germs prove that the milk is harmless. It is not the 
number but the character of the germs which determine their 
harmfulness. It is quite possible that milk containing very large 
numbers of bacteria may be entirely free from harmful species, 
while, on the other hand, milk with only a small number of 
bacteria may contain disease germs. 
A small number of germs may be considered as evidence of 
two conditions of the milk. First, it has been handled cleanly, 
z. é., not much stable dirt has entered the pail during the process 
of milking, and the probability is that the milk dishes were care- 
fully scalded; second, it may be evidence of freshness, for if the 
milk had stood many hours the number of bacteria would be 
quite large, unless the temperature of the milk is lowered so they 
cannot grow. With these facts in mind it will be more easily 
understood why milk in large cities, where it is frequently forty- 
eight hours old when delivered, shows large numbers of bacteria. 

* These investigations were made in the Bacteriological Laboratory of Wesleyan University 
under the direction of Prof. Conn. 
