134 Milk and its Ferments. 



bring about the change which we generally try to avoid, then 

 the lactic fermentation, which will assuredly result, may be 

 called an artificial one. Thus, a careful study of the life of 

 ferments allows us to apply conditions of control which can 

 thoroughly regulate a so-called artificial fermentation, and we 

 are able to obtain certain products by using the ferment micro- 

 organisms which produced them, the result of such an operation 

 being so certain that its success entirely depends on the skill 

 of the operator. I think that is what is generally understood 

 by fermentation, as the word is applicable to the so-called 

 artificial processes of commerce rather than to the operations of 

 nature, though the result may be much the same in both cases. 

 The micro-organisms of fermentation are generally quite 

 harmless, although in appearance some of them are hardly 

 distinguishable from the formidable microbes of disease. They 

 are one and all true ferments in a biological sense. 



It is important to remember that all ferments and moulds 

 have two distinct phases of existence. They live as organisms 

 when they can carry on their active functions as ferments, 

 or they are found as torpid spores or seeds, waiting opportuni- 

 ties of development. In this respect they resemble the more 

 familiar annual plants which at warm periods of the year bear 

 flowers and mature their seed, to wither and die afterwards as 

 the colder periods of the year overtake them, a certain amount 

 of warmth being necessary to favour their life. Many such 

 plants shed their seed, and the winds carry and distribute it. 

 As all ferments require moisture, it is quite impossible for them 

 to exist as living, active organisms in the air. Of course they 

 would be instantly dried up. They are therefore invariably in 

 the condition of dried, torpid spores, which as such not only 

 demand a suitable medium or soil in which to grow, but also 

 some little time before they can germinate. Some ferment 

 spores germinate in a few hours, others require as many days ; 

 and this simple difference allows one kind of organism to 

 develop to thousands or millions, before another kind of spore 

 with the same opportunities has been able to awaken to life, 



