188 BUTTER-MAKING. 
It seems that during cream-ripening the development of 
acid, aroma, and flavor go hand in hand. This does not neces- 
sarily indicate that they are produced by the same cause. It 
is possible that the flavor and aroma substances are chemically 
produced from the various by-products of the germs. 
Bacteriologists do not agree as to what species of bacteria 
is responsible for the high quality of flavor and aroma of butter. 
Conn * claims that the germs which act upon the nitrogenous 
Beeb, 
Fic. 122-—The McAreavy cream- Fig. 123.—The Miller cream-ripening 
ripening vat. vat. 
matter of milk are associated with the lactic-acid-producing 
bacteria in the production of desirable butter flavors. Weig- 
man asserts that the best results are obtained when a variety 
of species work together in the cream. He has isolated a single 
species of germ which produced alcohol and lactic acid as 
by-products, and which, according to experimental evidence 
deduced by him, is capable of producing the delicate butter 
flavors. Freudenrich has also studied a species of germ which 
produced alcohol and lactic acid as by-products, and was able 
to produce the characteristic butter flavors. Eckles has studied 
this question of flavor production during cream-ripening. He 
comes to the conclusion that the flavor and aroma substances 
* Storr Station, Conn. 
