74 Report of the Department of Bacteriology of the 



cheese curd. Here the presence of the acid reaction resulting 

 from the breaking up of sugar gives then> an advantage over their 

 competitors and this advantage is increased by the continued 

 breaking down of the sugar contained in the curd. 



The carhest attempt at determining the number of bacteria of 

 different kinds present in ripening cheese by Adametz^ showed 

 that in both emmenthaler and backstein the lactic acid group in- 

 cluded by far the larger part of the individuals. The work of von 

 Freudenreich'^ on emmenthaler cheese has emphasized the fact 

 that during the ripening period of this cheese there are few but 

 lactic bacteria present. Russell & Weinzirl^ showed that while a 

 considerable number of liquefying bacteria was present in the milk 

 at the time the rennet was added this group suffered a marked 

 decline during the curing, while the lactic-acid germs flourished, 

 especially during the first few weeks of the life of a cheddar 

 cheese. 



In a recent article Babcock, Russell, Vivian & Hastings^ have 

 demonstrated in detail that the ability of lactic-acid bacteria to 

 displace the other forms in cheese depends primarily upon the 

 action of these germs upon the milk sugar. When the milk sugar 

 was largely removed from the fresh curd by repeatedly washing 

 it with warm water the liquefying bacteria were abundant in the 

 resulting cheese and this cheese differed' markedly from the nor- 

 mal in its physical and chemical properties. In a duplicate por- 

 tion of this washed curd in which the sugar was artificially re- 

 placed, this increase in the number of liquefying germs was 

 prevented and this cheese did not differ widely from the normal in 

 its flora or in its physical or chemical properties. The most evi- 

 dent difference between the normal cheese and that made from 

 washed curd with the subsequent addition of sugar lay in the 

 failure of the latter to reproduce exactly the normal cheese flavor. 



When considering the flora of cheese, interest is commonly so 

 centered upon this striking increase in the lactic forms that the 



•Adametz. Land. Jakrb.,\6:22T. (1889.) 



7 von Freudenreich. Cent. /. Bakt., II Abt., I:i68. (1895.) 



8 Russell & Weinzirl. Ce7it. f. BakL, II Abt., 8:456. (1897.) 



* Babcock, Russell, Vivian & Hastings, Ann. Rept. Wis. Station, 18:i62 

 (1901.; 



