178 



THE BOOK OF BUTTER 



Later Rogers ^ ran another series of experiments with the 

 following results. In this series there were twelve cans 

 of creamery butter from a single churning as in the above 

 experiments. It was held in the laboratory seventy-three 

 days and then was placed in an incubator at 23° C. 

 (73° F.) : 



Table XXI — Bacteria and Yeasts per Gram op Butter 



(Series 22) 



° Only a few liquefiers. 



The number of lactic acid bacteria in the first examina- 

 tion constituted over 99 per cent of the total number. 

 They decreased rapidly, until at the end of 116 days none 

 was left. The liquefiers were more persistent. The 

 results reported in Table XXI are similar to those of 

 Table XX. Rogers' summary is given in the following 

 words : " It is quite evident that the microscopic life 

 existing in the butter can be considered as only indirectly 

 responsible for the change in the acidity or the flavor. 

 In series 22 there was no perceptible change in the acid 

 number until the bacteria had reached unimportant 

 numbers and the yeasts had nearly disappeared. In 



' Rogers, L. A., Canned Butter, U. S. Dept. of Agri., B. A. I., 

 Bui. 57, pp. 11-13, 1904. 



