88 THE STORY OF GERM LIFE. 



ing of cream, it is a process that occurs some- 

 what slowly. It is a chemical change which is 

 accompanied by the destruction of proteid mat- 

 ter; it takes place best at certain temperatures, 

 and temperatures which we know are favourable 

 to the growth of micro-organisms, all of which 

 phenomena suggest to us the action of bacteria. 

 Moreover, the flavours and the tastes that arise 

 have a decided resemblance in many cases to the 

 decomposition products of bacteria, strikingly so 

 in Limburger cheese. When we come to study 

 the matter of cheese ripening carefully we learn 

 beyond question that this a priori conclusion is 

 correct. The ripening of any cheese is depend- 

 ent upon several different factors. The method 

 of preparation, the amount of water left in the 

 curd, the temperature of ripening, and other mis- 

 cellaneous factors connected with the mechanical 

 process of cheese manufacture, affect its charac- 

 ter. But, in addition to all these factors, there is 

 undoubtedly another one, and that is the number 

 and the character of the bacteria that chance to 

 be in the curd when the cheese is made. While it 

 is found that cheeses which are treated by different 

 processes will ripen in a different manner, it is also 

 found that two cheeses which have been made 

 under similar conditions and treated in identically 

 the same way may also ripen in a different manner, 

 so that the resulting flavour will vary. The varia- 

 tions between cheeses thus made may be slight 

 or they may be considerable, but variations cer- 

 tainly do occur. Every one knows the great dif- 

 ference in flavours of different cheeses, and these 

 flavours are due in considerable measure to fac- 

 tors other than the simple mechanical process of 

 making the cheese. The general similarity of 



