196 LACTIC ACID BACTERIA IN DISTILLING, ETC. 



wort is regarded with favour and its development encouraged. This applies to 

 the so-called " Weissbier " (white beer). No careful bacteriological investigation 

 of the acidification process, which plays such an important part in the prepara- 

 tion of this refreshing beverage, has yet been made. Possibly Saccharobicilhis 

 pastorianus is concerned therein ; at present, however nothing definite can be 

 stated on this point. 



A considerable amount of acidity is produced in the Belgian beers known as 

 Lambic, Faro, and Mars, beverages prepared by spontaneous fermentation with- 

 out any addition of yeast. The boiled and re-cooled wort is placed in barrels 

 which are only partly filled, the empty internal space communicating with the 

 external air by a small aperture. Sufficient yeast-cells to set up fermentation 

 are left adhering to the walls of the casks from the previous fermentation, so 

 that after a lapse of twenty-four hours an evolution of gas is already noticeable. 

 In addition to alcoholic ferinentaton, lactic, and subsequently also acetic, fermen- 

 tation sets in. L. v. D. HULLB and H. VAX LAER (I.) published in 1891 the results 

 of a chemical investigation of this matter. The more important of these are 

 tabulated below : 



The beverage is consumed after a storage period of three to five years, and, in 

 its matured condition, is known as " gueuse Iambic." The acidity then amounts 



to about i per cent., and is 

 masked by an addition of 

 sugar immediately before 



FIG. 52. Section through Ginger-beer Plant. 

 The cells of Saccharomyces pyriformis are surrounded by the 

 cells of Bacterium vermiforme, the membranes of which are 

 very much thickened and swollen. Magn. 680. (After H. 

 M. Ward.) 



mentation also occurs in the 

 case of ginger-beer (to which 

 reference has already been 

 made in 64). The prepara- 

 tion of this foaming acid 

 beverage, which is largely 

 consumed in England in the 

 summer-time, is a very simple 

 matter. To a 10-20 percent, 

 solution of sugar are added 

 a few pieces of ginger and 

 a couple of granules of the ginger-beer plant the whole being then left 

 to stand uncovered. The liquid soon begins to ferment briskly, is bottled 

 at the end of twenty-four hours, and consumed within the next two days. 

 The so-called ginger-beer yeast was more closely examined by H. M. 

 WARD (II.). It consists of whitish translucent masses about the size of a hazel- 

 nut, and is a mixture (Fig. 52) of a yeast, Saccharomyces pyriformis, and a fission 

 fungus. The cell-walls of the latter organism are gelatinised in a manner with 

 which we shall become acquainted later on, more particularly in the case of cer- 

 tain filamentous bacteria : the greatly swollen outer layers of the cell-membrane 



