444 Bacteria in Relation to Country Life 



comparatively low temperatures of the late fall and 

 winter. 



In the course of time, a membrane or skin is formed 

 on the surface of the sauerkraut. It is found to consist 

 largely of Oidium lactis, and of certain yeasts. These 

 organisms begin to consume the lactic acid formed by 

 the bacteria, finally reducing its amount to such an 

 extent as to permit the growth of decay and putrefaction 

 bacteria and the decomposition of the sauerkraut. It 

 has been observed that at a certain point in this change 

 the juice may be alkaline, while the sauerkraut itself 

 is still acid. Higher temperatures encourage membrane- 

 formation and the destruction of the acid, hence, the 

 sauerkraut may be kept in condition for a longer time 

 when stored in cold cellars. Under the best of conditions, 

 however, the acid will gradually disappear and the sauer- 

 kraut will then spoil. It should be noted at the same time 

 that properly prepared and stored sauerkraut will keep 

 for a year, and can undoubtedly be made to keep longer 

 when the growth of Oidium lactis is more or less com- 

 pletely suppressed. 



The fermentation in the different casks of the same 

 factory is remarkably uniform. Bacterium lactis acidi 

 and Bacillus coli communis appear with great regu- 

 larity in the early stages of the process, as do certain 

 yeasts. Similarly, in the later stages, Oidium lactis always 

 becomes prominent. It would seem, therefore, that the 

 organisms present on the cabbages, as well as the com- 

 position of the juice and the prevailing temperatures 

 in the pickling establishments, are, on the whole, fairly 

 constant. 



