254 STATE BOARD OF AGRICULTURE 



They were put away for three weeks, at the end of which time no apparent 

 change had taken place, but ropiness existed. The caseine was then pre- 

 cipitated and found to equal the usual per cent, estimated in connection 

 with the coagulated albumen. The amount of sugar was also ascertained 

 to be normal. Judging from this work, the bacteria evidently feed upon 

 the milk without producing any preceptible change, unless the change is 

 so slow that a much longer time would be required. 



The acidity was studied by taking two lots of the same milk which had 

 been sterilized and treated together, and adding to one the bacillus and 

 keeping the other as a control. The examination showed that the amount 

 of acidity was not increased but very slightly decreased. Several repeti- 

 tions gave the same results. In connection with this, work upon a num- 

 ber of slightly acid bouillon cultures demonstrated that the acidity was 

 reduced. So far as it was possible to test it, the secretion of the bacilli 

 was alkaline, but this is not positive since it is quite possible that foreign 

 material might have been present to influence the reaction. No odors 

 were perceptible in any of the media. This fact is quite significant in the 

 study of any decomposition. 



Butter: The work in connection with the butter I owe to Mr. G. H. 

 True of this station Separator cream was employed in two lots of equal 

 amounts. In one, the bacillus was introduced in large quantities; in the 

 other, the bacillus in the same quantities was not introduced until it had 

 been Pasteurized at 70° C. for twenty minutes. Both lots were then placed 

 away and allowed to ripen for twenty-four hours, when they were churned. 



The loss of fat in the butter- milk was 2.2% in the case of the un -Pasteur- 

 ized cream and 2.8% in that of the Pasteurized cream. The acidity of the 

 Pasteurized cream was .27% and of the un- Pasteurized .57%. The 

 time required to churn the Pasteurized cream was seventeen minutes and 

 the un-Pasteurized cream twenty-seven minutes. 



It will be seen that considerable butter-fat was lost. This was doubtless 

 due to the holding of the fat globules in the adhesive secretion of the bac- 

 teria, for if the fat globules are once embedded in this material, it is ex- 

 tremely difficult to liberate them. The difference in the acidity is doubt- 

 less due to the fact that where the cream was Pasteurized, most of the lactic 

 acid bacteria were destroyed, consequently the conditions usually present 

 and favorable for the growth of lactic acid bacteria were changed. In the 

 un-Pasteurized cream this class of bacteria performed its usual function. 

 The difference in the time of churning is very noticeable. It is either due 

 to the Pasteurization of the milk or to the action of the bacteria of ropy 

 milk upon that substance which holds the fat globules. There is nothing, 

 however, in the biological history of this bacillus which would indicate any 

 such peptonizing action, yet I am not ready to say that it does not exert 

 some influence upon the cream. 



The flavor of the butter was not improved in the case of the un-Pasteur- 

 ized cream and when it was Pasteurized, the butter produced was insipid 

 to the taste. No peculiar aroma was present. 



Temperature : This bacillus grows best at about 30° C. It is killed at 

 60° C. for twenty minutes. Freezing it for three hours has no influence 

 whatever upon its vitality, and when it is transplaated, the development 

 is as rapid as though it had been cultivated under the most favorable 

 circumstances. 



