12 STORRS AGRICULTURAL EXPERIMENT STATION. 
ditt from the cow and the stable and made their way into the 
milk during the milking. Inasmuch as it had also been previ- 
ously found that hay or hair from the cows’ limbs showed the 
presence of these two organisms, the conclusion was inevitable 
that one source of B. actdi lactict IJ, and LB. lactis aerogenes 
> was the dirt and dust of the stable. ‘They were, therefore, a 
secondary contamination of the milk. It was, however, sur- 
prising that B. acédi lactice 1. was not found on these plates in 
spite of the fact that it is so universally present in the later 
stages of milk souring. It was thought that the explanation 
of this might probably be that they were present in small num- 
bers, but owing to the numerous liquefying colonies found in 
the gelatin plates, could not be detected before the gelatin 
plates were completely liquefied. 
Parallel with these experiments a study was made of the 
ripening of cream obtained from the milk. Inasmuch, how- 
ever, as Conn and Esten in a previous paper in this Report 
have thoroughly discussed the subject of cream ripening, the 
results of these experiments will be omitted. It need only be 
stated that the results were identical with those obtained by 
Conn and Esten, namely, that unripened cream contains small . 
numbers of lactic bacteria, but that these increase rapidly dur- 
ing the ripening until at its close they comprise over 90 per 
cent. of the whole. 
Experiments Nos. 7, 8, and 9.—In the previous experiments 
the work was confined in each case to a single cow. The 
question then arose whether it might not be possible that the 
milk of these particular cows contained no lactic organisms, 
but that this would not be true of the milk of cows in general. 
To settle this question the following experiment was performed: 
In the barn there were 70 cows that could be used for these 
experiments, and upon three successive days milk was drawn 
from each one of the 70 cows immediately into sterile vials 
such as before used, each vial being marked with the number 
of the cow from which the milk was drawn. The vials were 
plugged with sterile cotton, the cotton being removed only for 
the milking and immediately replaced, so that the milk had 
only a few second’s exposure to the air. It was believed that 
in this way most of the external contamination of the milk 


ee ee a a ee ee 
te a 
ee EP ee a ee ee ee ee 
ee aa ee ne ee ee ee a 
