156 Dairy Bacteriology. 



Freudenreich, 1 and the writer, 2 independently, have 

 determined the character and numbers of bacteria in 

 Emmen thaler and American cheddar cheese. Their re- 

 sults practically agree as to the course of the bacterial 

 changes in these two kinds of cheese. 



First, there is a marked decrease in numbers lasting 

 for a day or so. This is then followed by an enormous 

 numerical increase that is entirely produced by the marked 

 development of the lactic acid forms. Synchronous with 

 this increase, the peptonizing and gas-producing bacteria 

 gradually disappear, so that in a short period of time, the 

 bacterial flora seems to be made up very largely of this 

 lactic type of organisms. This rapid development is 

 followed by a gradual decline that continues in an old 

 cheese for two years or more. As the cheese dries out, 

 the conditions become unfavorable, and as the lactic acid 

 species are not able to form spores they soon succumb to 

 their unfavorable environment. The following data 

 illustrate this: 



Bacteria per gram in cheddar cheese at different stages of 

 ripening . 



Date of analysis. Total number. Lactic acid bacteria. 



Curd 26,532,000 22,560,000 



ist day 21,060,000 20,176,000 



5th day 43,716,000 39,680,000 



loth day 98,080,000 97,280,000 



i 9 th day 48,140,000 48,000,000 



36thday.... 11,171,000 11,000,000 



This condition has been found to exist not only in 

 American cheddar cheese but in Canada 3 and England 4 . 



1 Freudenreich, Landw. Jahr. d. Schweiz, 4: 17; 5: 16. 



2 Russell, 13th Wis. Expt. Stat., p. 95, 1896. 



3 F. C. Harrison (unpublished data). 



* Lloyd, Bath, and West of Eng. Soc. Kept., 2: 180, 1892. 



