BACTERIA IN THE DAIRY. 19 
appeared to me to be necessary to experiment, not with one or 
two, or with half a dozen, species, as has been generally done 
by bacteriologists hitherto, but with as large a number of the 
species of dairy bacteria as 1s possible. For two years or more 
I have been engaged in testing the effect upon cream ripening 
of the various kinds of bacteria which have been found in milk 
and cream. Some of these experiments have been reported in 
earlier publications. ‘The present series began in May, 1895. 
In this work I have been assisted by Mr. William Esten, who 
has carried out a large portion of the practical experiments. 
BACTERIA OF ORDINARY CREAM. 
The first task in this series of experiments was to collect 
from creameries and from dairies a large variety of bacteria. 
It was especially desirable to obtain those found in creameries 
during the months of May and June, inasmuch as these months 
are commonly characterized by the production of the best 
quality of butter. During May and June of 1895 quite a num- 
ber of visits were made to creameries in Connecticut, including 
those at Cromwell, Durham, Wapping, Elmwood, Farmington, 
and Ellington. Some of these creameries were visited two or 
three times, others only once. From the cream thus obtained 
as many different species of bacteria as possible were taken at 
once and set aside for future work. At subsequent periods 
other visits have been made to the same places. Other samples 
of milk and cream have been obtained from dairies at Storrs, 
and from two or three different dairies in Middletown. From 
these various sources nearly one hundred different types of 
bacteria have been obtained, most of which have been carefully 
studied and tested in cream ripening. 
In thus describing them as different types I would not imply 
that they are necessarily different species, but simply that they 
show some differences in their method of growth. Bacteriolo- 
gists do not yet know what constitutes a species among these 
organisms, and it is extremely probable that some of the hun- 
dred referred to really belong to the same species of bacteria, 
some of them being only slight variations of others. They all 
produce different effects, and have consequently been studied 
independently of eachother. Alleofithe general types of 
milk bacteria are included among this list. It includes some 
