32 STORRS AGRICULTURAL EXPERIMENT STATION. 
deleterious effect upon tts butter. This will produce tn all cases a 
Salling off in the quality. The trouble may be due, perhaps, to 
a single cow, tnasmuch as the milk of individual cows may some- 
limes contain species of organisms not Sound in others, even tn 
the same barn. Tt is, however, commonly tniposstble for the 
Sarmer or the butter-maker to find the source of such tnjurious 
bacteria. 
¢. Creameries and dairies will in many cases be supplied with 
bacteria giving rise to desirable flavors, aromas, and a proper 
amount of acid. This is commonly the case from the fact that the 
go0d-flavoring species are abundant, but it will not always be 
true. It 1s more common in June than at other seasons of the 
year, simply because the variety of bacteria ts greater at this time, 
and hence the greater likelthood that some species which produce 
the proper aroma and flavor will be present. Probably, also, some 
of the destrable species are especially abundant in the green food 
of cows tn June. 
5. Lf cream be inoculated with a large culture of some par- 
ticular kind of bacteria, this species will Srequently develop so 
vapidly as to check the growth of the other bacteria present and 
thus, perhaps, prevent them from producing their natural effects. 
flence, tt will follow that the use of starters will commonly give 
vise to favorable results, even though the cream is already some- 
what largely impregnated with other species of bacteria before the 
enoculation with the artificial starter.  Thds fact lies at the basis 
of the use of artificial starters either with or without pasteuriza- 
tion. To produce the desirable result tt ts necessary to have the 
starter contain a large abundance of some Javorable species which 
by tts growth can both check the development of the ordinary cream 
bacteria and can develop a proper Jlavor by itself. 
DETAILS OF EXPERIMENTS. 
Before describing the experiments in detail a few words more 
may be in place as to the method of experimentation and 
recording results. The method by which different species 
have been tested as concerns their influence upon cream ripen- 
ing and butter have already been described. It will be seen 
from the method thus given that the comparisons between the 
effects of the different organisms upon butter have been made 
under conditions in which they can be strictly accurate. When 
