28 ' STORRS AGRICULTURAL EXPERIMENT STATION. 
the acid-producing class, while nine belonged to the class 
developing alkaline reaction. 
From these facts it appears to me a safe and perfectly legiti- 
mate inference that flavor is a matter entirely distinct from 
acid. It will be noticed that among the acid-producing species 
there are some that develop good flavor, while others develop 
a decidedly unpleasant flavor; and it will be noticed that 
among the species producing good flavors in the butter, while 
many of them are acid producers, a large number, eleven out of 
twenty, are among those that develop no acid. In speaking of 
the flavor as entirely distinct from the acid it is, of course, not 
meant to imply that they may not be associated. It may com- 
monly happen, as will be noticed from these results, that the 
same species of bacteria may develop acid and flavor. This 
undoubtedly is the case with many of the bacteria of milk, and 
with most of the species of bacteria that are used by various 
butter-makers as cultures for artificial fermentation. Never- 
theless, the fact that many of the species of bacteria produce 
acid and, at the same time, an unpleasant flavor and disagree- 
able effect upon the butter, while pleasant flavors are developed 
by species of bacteria which have not the acid-producing power, 
indicates clearly enough that the development of acid is not the 
_same thing as the development of flavor. The development of 
the acid comes, as is well known, from the decomposition of 
the milk sugar, but the development of flavor comes, at all 
events, not from the same kind of decomposition of the milk 
sugar, and probably comes from some other kind of decomposi- 
tion effect produced by these bacteria upon some of the 
ingredients of the cream. It is impossible at the present time 
to state, any more closely, to what the flavor is due, but the 
facts outlined above show clearly enough that the development 
of flavor and the development of the acid are not identical, and 
that while acid organisms may be the most promising ones for 
giving rise to the proper flavor in cream, these flavors may be 
due in many cases to organisms of an entirely different char- 
acter. While, therefore, the lactic bacteria may be regarded 
as commonly producing the butter flavor in practical butter- 
making, they do not do this simply because they produce acid, 
and we must recognize that other types of bacteria probably 
assist in producing the desired flavor. It is important to note 
