72 Milk and Its Products. 



This germ is occasionally found in milk, and imparts 

 to it a red color which is easily confounded with 

 the red color due to the presence of blood from a 

 wounded udder. A single germ rarely occasions 

 more than a single fermentation . Often two or more 

 are combined in the fermentation, and in many cases 

 there are a large number of different germs that 

 bring about the same fermentation. This is notably 

 true of the lactic and putrefactive fermentations. 

 The effect of the various fermentations is such as to 

 destroy the value of the milk as such, if they are al- 

 lowed to proceed to any great length ; but the manu- 

 facture of butter is greatly aided by many of these 

 fermentations, and the presence of certain germs is 

 absolutely indispensable to the manufacture of cheese. 

 Relation of milk bacteria to the human system. — By 

 far the greater number of germs ordinarily found in 

 milk are absolutely harmless, and may be taken into 

 the human system in large numbers with perfect 

 impunity, the germs of specific disease excepted, and 

 with these latter it is the products formed from their 

 growth rather than the germs themselves from which 

 danger comes. There are probably no germs normally 

 found in milk that may be classed as harmful. This 

 is also true of a considerable number of fermen- 

 tation products resulting from the growth of the 

 germs in the milk. Many of these products give 

 to the milk or its product an unpleasant taste or 

 physical appearance, but are otherwise perfectly 

 harmless. There are, however, certain germs which 

 produce a fermentation which results in the forma- 



