76 LOUIS PASTEUR. 



instead of regularly reflecting it, as does the surround- 

 ing liquid. These specks go on increasing progres- 

 sively and rapidly. This is the mycoderma aceti 

 raised from the seeds which the wine or the added 

 vinegar contained, or which the air deposited ; just as 

 we see a field covered with divers weeds by seeds natu- 

 rally distributed in the earth, or which have been 

 brought to it by the wind or by animals. Even in 

 this last circumstance the comparison holds good, for 

 after you have put wine or vinegar in a warm place 

 there soon appear, whence we know not, little reddish 

 flies, so commonly seen in vinegar manufactories, and 

 in all places where vegetable matter is turning sour. 

 With their feet, or with their probosces, 'these flies 

 transport the seed. 



At Orleans the process for the manufacture of 

 vinegar is very simple. Barrels ranged over each 

 other have on each of their vertically-placed bottoms 

 a circular opening some centimeters in diameter, and 

 a smaller hole adjacent, called fansset, for the air to 

 pass in and out when the large opening is closed, 

 either by the funnel, through which the wine is intro- 

 duced, or by the syphon, which is used for draw- 

 ing off the vinegar. These barrels, of which the 

 capacity is 230 litres, are half filled. The manual 

 labour consists in keeping up a suitable temperature 

 in the vessel, and in drawing from it every eight days 



