TYPES OF BACTERI \ FDl'M) IX MILK 4 I 



signs of softening, because it is being converted into peptones,, 

 or other soluble substances. As these are formed, they are dis- 

 solved and the curd disappears. Since this is a process very 

 similar to digestion of milk, in the stomach and intestine, it is 

 customary to say that the curd is digesting. This may continue 

 until the whole curd is dissolved into a watery liquid, or it may 

 stop after it is only partly dissolved. (Fig. 18, C and D.) 

 With some species of this class the digestion occurs without 

 any previous curdling, the rennet action being slower than the 

 digestion. In these cases the milk simply becomes more trans- 

 parent, and analysis shows that it has digested much the same 

 as in the other cases where the curdling first appears. 



The liquefying bacteria are very numerous and are almost 

 always found in samples of fresh milk. They are of no great 

 importance in the ordinary handling of milk since they are 

 commonly overshadowed by the lactic acid bacteria. Though 

 they sometimes produce a sweet curdling, they rarely develop 

 sufficiently in milk to show signs of the digestion just de- 

 scribed. Occasionally, however, they are of significance in 

 cheese making. During the long ripening of cheese they have 

 a better chance to grow than in milk. Whether they have j 

 much influence upon the hard cheeses is not fully known yet, > 

 but in the ripening of soft cheeses, they sometimes multiply so \ 

 extensively as to produce very bad results, and to cause much--' 

 loss to the cheese makers. \Vhile, therefore, they are of little 

 importance to the one who handles milk, they play a consider- 

 able part in the making of cheese. Some instances have been 

 described where this class of bacteria seems to be particularly 

 abundant and develops instead of the lactic type. The trouble 

 has been attributed to the bacteria in the udder, where they 

 are thought to be especially abundant in the case of incomplete 

 milking. 1 



^Burri. Milchztg., p. 705, 1903. 



