FERMENTATION. 547 



bacteria, and thus postpones the evil day. By boiling her 

 milk she also extends its period of sweetness. Some weeks 

 ago in the Alps I made a few experiments on the influence 

 of cold upon ants. Though the sun was strong, patches 

 of snow still maintained themselves on the mountain 

 slopes. The ants were found in the warm grass and on 

 the warm rocks adjacent. Transferred to the snow the 

 rapidity of their paralysis was surprising. In a few seconds 

 a vigorous ant, after a few languid struggles, would wholly 

 lose its power of locomotion and lie practically dead upon 

 the snow. Transferred to the warm rock, it would revive, 

 to be again smitten with death-like numbness when retrans- 

 f erred to the snow. What is true of the ant is specially 

 true of our bacteria. Their active life is suspended by 

 cold, and with it their power of producing or continuing 

 putrefaction. This is the whole philosophy of the preser- 

 vation of meat by cold. The fishmonger, for example, 

 when he surrounds his very assailable wares by lumps of 

 ice, stays the process of putrefaction by reducing to numb- 

 ness and inaction the organisms which produce it, and 

 in the absence of which his fish would remain sweet and 

 sound. It is the astonishing activity into which these 

 bacteria are pushed by warmth that renders a single sum- 

 mer's day sometimes so disastrous to the great butchers of 

 London and Glasgow. The bodies of guides lost in the 

 crevasses of Alpine glaciers have come to the surface forty 

 years after their interment, without the flesh showing any 

 sign of putrefaction. But the most astonishing case of 

 this kind is that of the hairy elephant of Siberia which 

 was found incased in ice. It had been buried for ages, but 

 when laid bare its flesh was sweet, and for some time 

 afforded copious nutriment to the wild beasts which fed 

 upon it. 



Beer is assailable by all the organisms here referred to, 

 some of which produce acetic, some lactic, and some 

 butyric acid, while yeast is open to attack from the bacteria 

 of putrefaction. In relation to the particular beverage the 

 brewer wishes to produce, these foreign ferments have 

 been properly called ferments of disease. The cells of the 

 true leaven are globules, usually somewhat elongated. 

 The other organisms are more or less rod-like or eel-like in 

 shape, some of them being beaded so as to resemble neck- 

 laces, Each of these organisms produces a fermentation 



