20 STORRS AGRICULTURAL HXPERIMENT STATION. 
bacteria which sour milk by producing lactic acid, others which 
curdle the milk by producing a rennet-like ferment, but render- 
ing the milk alkaline, others, again, which exert a putrefactive 
effect upon the milk, and still others that have seemingly no 
effect whatsoever upon the milk or cream. ‘The various types 
were in almost equal abundance among the species collected, 
except that the number of forms that have no appreciable effect 
upon milk is considerably larger than those belonging to any 
of the other classes. 
In the early summer the variety of bacteria in the cream 
has been found to be greater than at the other seasons 
of the year thus far tested. No examinations have yet been 
made of the cream of the late summer or early fall. In nearly 
all of the samples of cream collected in May, and particularly 
in June, the number of different species was very great, not 
only when different samples were compared with each other, 
but in the same sample of cream. This would naturally have 
been anticipated, and is probably closely associated with the 
green food of the cows. It appears not unlikely that in this 
fact lies the explanation of the high quality of butter flavor 
commonly developed during these months. Not only is the 
variety greater, but the number of bacteria in the cream 
during these months is vastly in excess of that found under 
similar conditions in the cooler months of the year. No accu- 
rate quantitative tests were made, but the difference in the 
number of bacteria found in the samples of cream tested in June 
and those tested in February was very great indeed, even 
though the age of the cream was the same in the two cases. 
This fact is, of course, due to the teniperature which stimulates 
bacterial growth. 
Another point in the same connection is the difference in the 
species of bacteria found at the same creamery at different 
times. Such samples, even though following each other at 
short intervals, showed a considerable difference in the types of 
bacteria found. This is in part due to the fact that no bac- 
teriological examination of cream can disclose all of the kinds 
of bacteria therein, and the bacteriological analysis is, there- 
fore, in every case, very incomplete. Two samples of the 
same cream would doubtless show some differences for this 
reason. But this is not wholly the explanation of the matter, 
