FERMENTATION AND DISEASE. 143 



given partly because the yeast of this beer, instead of rising to the 

 top and issuing through the bung-hole, falls to the bottom of the 

 cask; but partly, also, because it is produced at a low temperature. 

 The other and older process, called high fermentation, is far more 

 handy, expeditious, and cheap. In high fermentation eight days suf- 

 fice for the production of the beer; in low fermentation, ten, fifteen, 

 even twenty days, are found necessary. Vast quantities of ice, more- 

 over, are consumed in the process of low fermentation. In the single 

 brewery of Dreher, of Vienna, 100,000,000 pounds of ice are con- 

 sumed annually in cooling the wort and beer. Notwithstanding 

 these obvious and weighty drawbacks, the low fermentation is rapidly 

 displacing the high upon the Continent. Here are some statistics 

 which show the number of breweries of both kinds existing in Bohe- 

 mia in 1860, 1865, and 1870 : 



I860. 1865. 18T0. 



281 81 18 



Low fermentation . . 135 459 831 



High fermentation 281 81 18 



Thus in ten years the number of high-fermentation breweries fell 

 from 281 to 18, while the number of low-fermentation breweries rose 

 from 135 to 831. The sole reason for this vast change a change 

 which involves a greater expenditure of time, labor, and money is 

 the additional command which it gives the brewer over the fortuitous 

 ferments of disease. These ferments, which, it is to be remembered, 

 are living organisms, have their activity suspended by temperatures 

 below 10 C, and as long as they are reduced to torpor the beer re- 

 mains untainted either by acidity or putrefaction. The beer of low 

 fermentation is brewed in winter, and kept in cool cellars ; the 

 brewer being thus enabled to dispose of it at his leisure, instead of 

 forcing its consumption to avoid the loss involved in its alteration if 

 kept too long. Hops, it may be remarked, act to some extent as an 

 antiseptic to beer. The essential oil of the hop is bactericidal : hence 

 the strong impregnation with hop-juice of all beer intended for ex- 

 portation. 



These low organisms, which one might be disposed to regard as 

 the beginnings of life, were we not warned that the microscope, 

 precious and perfect as it is, has no power to show us the real begin- 

 nings of life, are by no means purely useless or purely mischievous 

 in the economy of Nature. They are only noxious when out of their 

 proper place. They exercise a useful and valuable function as the 

 burners and consumers of dead matter, animal and vegetable, reducing 

 such matter, witli a rapidity otherwise unattainable, to innocent car- 

 bonic acid and water. Furthermore, they are not all alike, and it is 

 only restricted classes of them that are really dangerous to man. 

 One difference in their habits is worthy of special reference here. 

 Air, or rather the oxygen of the air, which is absolutely necessary to 

 the support of the bacteria of putrefaction, is absolutely deadly to 



