470 



STATE BOARD OF AGRICULTURE. 



expected, and therefore tlie initial counts of D and E are rather un- 

 certain. In culture C, the size of the colonies showed the same variations 

 mentioned in the preceding experiments, and the variations increased 



with the age of the culture. 



VI. THE INFLUENCE OP FOOD. 



It seems reasonable to suppose a priori, that the fermenting capacity 

 will be influenced by the food. It is well known that Bacterium lactis 

 aeidi produces less acid in sugar broth than in milk. It is also known 

 that certain strains produce larger amounts of acid in milk after the 

 addition of peptone. Whether this is due to a faster multiplication or 

 to an increase in the fermenting power of the single cell can be ascer- 

 tained by computation of the fermenting capacity- 



The Influence of Peptone. — Experiments concerning the influence of pep- 

 tone were carried on with the Strains II and IV. While Strain II 

 shows very little influence (Table XV) Strain IV reacts promptly by a 

 much faster and more vigorous acid formation (Tables XVI and XVII). 

 All these experiments were arranged in the same way. 100 cc. portions 

 of milk were sterilized discontinuously in Erlenmeyer flasks, some of 

 them receiving 1 g. of peptone (Witte) before the first heating. The 

 sterile flasks were inoculated with a measured amount of a young milk 

 culture of the strain under study. In the first two experiments, dupli- 

 cates were made, the difterence consisting only in the amount of inoculum. 

 In the experiment Avith Strain II (Table XV) the acidity and the 

 bacterial counts were taken every 12 hours, and with Strain IV which 

 develops much more slowly the data were obtained every 24 hours. 

 The experiments with Strain IV Avere carried out by Mr. C. F. Barnum. 



