74 LOUIS PASTEUR. 



is thereby transformed into acetic acid. The little 

 mycoderm is not less exacting than larger vegetables. 

 It must have its appropriate aliments. Wine offers 

 them in abundance : nitrogenous matters, the phos- 

 phates of magnesia and of potash. The mycoderm 

 thrives, moreover, in warm climates. To cultivate 

 it in temperate regions like ours it is well to warm 

 artificially the places where it is cultivated. But if 

 wine contains within itself all the elements necessary 

 to the life of the little mycoderm, this life is further 

 promoted by rendering the wine more acid through 

 the addition of acetic acid. 



What, then, can be more simple than to produce 

 vinegar from wine a manufacture which justly makes 

 the reputation of the town of Orleans ? Take some 

 wine, and after having mixed with it one-fourth or 

 one-third of its volume of vinegar already formed, 

 sow on its surface the little plant which does the work 

 of acetification. It is only necessary to skim off, by 

 means of a wooden spatula, a little of the mycodermic 

 film from a liquid covered with it, and to transfer it 

 to the liquid to be acetified. The fatty matters which 

 it contains render the wetting of it difficult. Thus, 

 when we plunge into the liquid the spatula covered 

 with the film, the latter detaches itself and spreads 

 out over the surface instead of falling to the bottom. 

 When we operate in summer, or in a room heated to 

 15 or 25 Centigrade in winter, in twenty-four or 



