BACTERIA IN THE DAIRY. ris} 
In table 13 it will be noticed that No. 7 and No. 9 are from the 
same source and give much larger numbers than the other tests. 
The milk in those two tests was from ten to twelve hours older 
than in the other samples, being night’s milk while all the others 
were morning’s milk. No. 10 is from the same source, but in 
that case a special request was made at the milk cart for morn- 
ing’s milk for examination. The result shows the difference 
between the morning’s and the previous night’s milk. 
The average in the thirteen tests made is a little less than one 
million per cubic centimeter (990,000). But if the average is 
taken without including No. 7 and No. 9, which were probably 
night’s milk, the average is reduced to less than 100,000 germs 
pec-cuvpic centimeter. 
BAC LERTA IN “BUTTER. 
Probably the first attempt at a quantitative estimate of bacteria 
in butter was made by Von Lafar at the Hygienic Institute of 
the University of Munich in the winter of 1890-91. He found 
that butter fresh from the churn contained an immense number 
of germs and that this number quickly fell to one or two millions 
or less per gram.* 
In the work here reported the changes in number of bac- 
_ teria in butter kept under usual household conditions have been 
studied. ‘The methods employed were practically the same 
as those already described for milk. The butter was weighed 
instead of being measured and the number of bacteria were 
calculated per gram* instead of per cubic centimeter. ‘Two lots 
of unsalted and two of salted butter obtained from the creamery 
as soon as made, were tested. In each instance the butter was 
received in pound prints and the first plates were made as soon 
as received. ‘The butter was kept in an ordinary refrigerator (at 
32° to 38° F.) and plates were made every few days. 
The first few tests were taken from different portions of the 
outside of the butter roll, as the difference between the number 
of germs living on the outside of the butter and those living on 
the inside were probably slight while the butter was fresh. 
Later, when the difference might be appreciable, the roll was cut 
at various places and samples taken from as near the center 
as possible for the inside determination, in order to compare it 
_ with the outside. 

* One pound weighs 454 grams. 
