1892.] Some Uses of Bacteria. 907 
get a little more butter from a given quantity of cream if you 
ripen it, and, above all (and this, perhaps, may be regarded as 
the chief value of ripening), the butter acquires that peculiar, 
delicate, pleasant aroma which is essential to a first-class qual- 
ity of butter, that peculiar aroma which is not acquired if you 
do not properly ripen your cream before churning it. 
Now the explanation of the production of that aroma is 
simply this: These bacteria are agents of decomposition. 
Bacteria, as they grow in any solution, tend to decompose it 
or pull it to pieces. If they growin an egg they decompose 
the egg and cause it to putrefy and decay, and when they 
begin to grow in your cream they begin the same process of 
decomposition. If you should let your cream ripen for a week 
or two you would very readily see that the process of decom- 
position had taken place, and your cream would become very 
offensive. The moment you begin to ripen your cream the 
bacteria begin to decompose it. Now as the result of decom- 
position a great many chemical products are produced, and 
they have all sorts of smells and‘ tastes. If you should let 
decomposition go far enough you would get the bad odor of 
decay, but you do not get that odor when decomposition 
begins. The first of the decomposition products are rather 
pleasant in odor and pleasant in taste, and if you churn your 
cream at that stage of decomposition your butter is flavored 
with the early decomposition products. This flavor is the 
aroma of good butter, this is what fancy butter-makers sell in 
the market and get a high price for. They get a high price, 
then, for the decomposition products of bacteria, for a proper 
tasting butter brings a higher price than that which does not 
have this aroma, and the aroma is the gift of bacteria. You 
may ask what becomes of the bacteria? It really makes little 
difference what becomes of them. Some go into the butter- 
milk, some go off in water used in washing, some go into the 
butter and the salt kills them. It is no matter where they go. 
After the butter is churned they are no longer of any import- 
ance to you or any one else; their career, so far as the dairy 
is concerned, is ended- 
