STUDIES ON FERMENTATION. O 



No. 1 of the engraving represents the ferments of turned 

 beer, as it is called. These are filaments, simple or articulated 

 into chains of different size, and having a diameter of about 

 the thousandth part of a millimetre (about vrxroo" inch). Under 

 a very high power they are seen to be composed of many series 

 of shorter filaments, immovable in their articulations, which 

 are scarcely visible. 



In No. 2 are given the lactic ferments of wort and beer. These 

 are small, fine and contracted in their middle. They are 

 generally detached, but sometimes occur in chains of two or 

 three. Their diameter is a little greater than that of No. 1. 



In No. 3 are given the ferments of putrid wort and beer. These 

 are mobile filaments whose movements are more or less rapid, 

 according to the temperature. Their diameter varies, but is 

 for the most part greater than that of the filaments of Nos. 1 

 and 2. They generally appear at the commencement of fermen- 

 tation, when it is slow, and are almost invariably the result of 

 very defective working. 



In No. 4 are given the ferments of viscous wort, and those 

 of ropy beer, which the French call filante. They form 

 chaplets of nearly spherical grains. These ferments rarely 

 occur in wort, and still less frequently in beer. 



No. 5 represents the ferments of pungent, sour beer, which 

 possesses an acetic odour. These ferments occur in the shape 

 of chaplets, and consist of the mycoderma aceti, which bears a 

 close resemblance to lactic ferments (No. 2), especially in the 

 early stages of development. Their physiological functions are 

 widely different, in spite of this similarity. 



The ferments given in No. 7 characterize beer of a peculiar 

 acidity, which reminds one more or less of unripe, acid fruit, 

 with an odour sui generis. These ferments occur in the form of 

 grains which resemble little spherical points, placed two together, 

 or forming squares. They are generally found with the fila- 

 ments of No. 1, and are more to be feared than the latter, 

 which cause no very great deterioration in the quality of beer, 

 when alone. "When No. 7 is present, by itself or with No. 1, 



